SatTrackCam Leiden station (b)log

Phobos-Grunt: a final TIP on where it came down

2012-01-23T23:24:00.002+01:00

USSTRATCOM today (Jan 23rd) has finally released a traditional format final TIP for Phobos-Grunt. It yields similar values to the ones initially circulating through Russian press releases (see earlier post here): 17:46 GMT (+/- 1 m) and a location in the southern Pacific, near 46 S, 87 W.

click map to enlarge

More thoughts on the Phobos-Grunt reentry

2012-01-16T15:05:00.001+01:00

It appears that the Russian news bulletins claiming that Phobos-Grunt reentered over the southern Pacific at 17:45 UT yesterday (see my previous post) rather were model predictions than reentry times based on actual final track detections. The Russians (nor the US, for that matter) actually do not have much in terms of tracking facilities in the indicated area (S-Pacific, S-America and S-Atlantic).

The southern Oceans: a blind spot

This highlights the problem, and the similarity between the UARS case last September and the current Phobos-Grunt case. In both cases, determining where it came down was likely hampered by the final revolution and final half hour or more of its trajectory being largely over remote and empty territory. Specifically, in both cases: the southern Oceans.

A lack of tracking facilities (and humans in general) in these areas, mean that they represent a large blind spot for those who's profession it is to track these objects. Once a satellite near decay starts to make its final passes and significant parts of that happen to be over these remote locations, it basically disappears into a black hole. That's what happened with UARS in September, and what now happened with Phobos-Grunt.

Not as in the movies

While some in the media and public have expressed frustration about the lack of published information (and the contradictory information) right after Phobos-Grunt presumably came down, I feel those people lack a realistic outlook on these matters. These people apparently expect that the military is able to determine a clearcut point of reentry within minutes after the satellite has reentered.

In reality, this is not how it works. The military has intermittentdetections when the object moves over tracking facilities, spread wide and far over anumber of places around the globe. They do not have continuous coverage. They cannot track where they have notracking facilities. And the big and empty southern oceans represent a large swath of Earth where that is the case.

In Hollywood movies and TV-series, the military (or "NASA", even though in reality it is not NASA doing the tracking) are portrayed as having a second-to-second real-time tracking opportunity of objects, with a moving dot on the screen that disappears in real-time as soon as the satellite reenters. That however, as most things in movies, is a highly unrealistic view which has little resemblance to reality.

It will take the professional analysts at USSTRATCOM and elsewhere some time to ponder the last tracking data, detections and non-detections, and maybe even then there will remain uncertainty about where Phobos-Grunt came down. Such is life, and reality.

Space-Based detections?

In the case of UARS last September, some of us have had some suspicion that Space-Based observations (Infra-Red detections by the early warning satellites of Missile Defense) were perhaps involved in the final determination of the point of reentry. These resort under another part of the military, and comments by those "in the loop" have indicated that normally there is little data exchange between these guys and the groundbased tracking guys. There is also the open question whether reentry fireballs are bright enough for these space-based systems (the DSP and SBIRS satellites) to detect them. As the specifications of these systems are of course classified, little is known about this.

[Updated] Phobos-Grunt down over the southeast Pacific?

2012-01-15T21:12:00.001+01:00

click map to enlarge

Early reports in the Russian media report that Phobos-Grunt has come down over the southern Pacific Ocean at 17:45 UT (15 Jan).

These same Russian media have misinterpreted decay bulletins in the (recent) past however, so this is all under some caveat until clear data from non-media sources (e.g.a USSTRATCOM TIP message) appears.

The map above is a preliminary map based on orbital elements from 16:35 UT, an hour before the reentry, and shows the approximate position for Phobos-Grunt for 17:45 UT. There might be some small discrepancy between the pictured position and real position as it is based on orbital elements from one hour before the reentry.

Note added 20:30 GMT: Confusingly, Ria-Novosti in a new press release mentions another time and position: 17:59 UT and the Atlantic, 18S and 311 E (49 W). This exemplifies what I mean above with the caveats....

Update 20:40 GMT: USSTRATCOM released a TIP message at 20:34 UT simply saying: "Object Decayed Inside Predicted Window".
That probably means: within the window of their earlier TIP message: 16:59-17:47 UT. This could be taken to support the 17:45 UT value of the Russians and reentry over the S-Pacific.

Summary of current Phobos-Grunt reentry predictions (15 jan 11:00 UT)

2012-01-15T12:28:00.002+01:00

Summary of current Fobos-Grunt reentry predictions, round-up of predictions compiled at 15 Jan 11:00 UTC:

USSTRATCOM (14 Jan 20:30): interval 14:52 - 19:40 UTC
Harro Zimmer (15 Jan 07:10): 17:49 +/- 45 m UTC
Ted Molczan (15 Jan 04:59): 20:39 +/- 3 hrs UTC
Aerospace Corp. (15 Jan 06:25): 19:21 +/- 3 hrs UTC
Roscosmos (14 Jan): 18:36 UTC (uncertainty window not stated)

Listed are: source; time prediction was issued (UTC); predicted time and uncertainty interval, or predicted interval.

My own current prediction, using Alan Pickup's SatEvo, current F10.7cm flux and 09:21 UT epoch orbital elements: 20:07 +/- 2 hrs.

PLEASE take note of the still large uncertainty intervals. As yet, it is still impossible to realistically say where it will come down.

[Updated] Summary of Phobos-Grunt reentry predictions as off 14 Jan, 13:00 UTC

2012-01-14T14:23:00.000+01:00

Current predictions by various sources for the reentry of the failed Russian Mars probe Fobos-Grunt all still have a very large uncertainty window. Therefore, it is still impossible to provide any realistic statements about the when and especially where the reentry will happen. Suggestions in the press such as these only demonstrate a continuing and thorough misunderstanding of the whole issue among some journalists.

Perhaps as a result of this, USSTRATCOM has changed the way it presents it's Fobos-Grunt reentry predictions. While for other objects they still use the classical TIP format (time with uncertainty interval, and position at the nominal time), they altered the presentation for F-G: they only list the uncertainty interval, without positions or nominal time. Given the way that TIP messages were taken completely out of context and misinterpreted in the press recently (e.g. the notorious and utterly misinformed Novosti-RIA publication here), this is all a very understandable precaution.

A summary of the current predictions (round-up of predictions at 14 Jan, 13:45 UTC. Listed are: source; time/date prediction was issued; predicted time plus uncertainty interval, or uncertainty interval only):

USSTRATCOM (13 Jan 15:30 UTC): 15 Jan 08:25 - 16 Jan 03:37 UTC
Harro Zimmer (13 Jan 11:51 UTC): 15 Jan 17:05 +/- 3 hrs UTC
Ted Molczan (14 Jan 08:35 UTC): 15 Jan 22:31 +/- 8 hrs UTC
Celestrak (T.S. Kelso, 14 Jan 11:00 UTC): 17 Jan 10:04 +/- 1 day UTC
AeroSpace Corp. (13 Jan 10:40 UTC): 15 jan 17:52 +/- 14 hrs UTC
Roscosmos (14 Jan UTC): 15 Jan ~~21:51~~ 17:51 UTC (no uncertainty window listed)

[added 15:45 UT, 14 Jan] My own estimate, using Alan Pickup's SatEvo and the current space weather (F10.7 cm flux) and the Jan 14.54 orbit, is for 15 Jan, 21:50 +/- 7 hrs UTC.

PLEASE take note of the large uncertainty windows on all these predictions! The uncertainty amounts to many revolutions of F-G around the Earth, so it is impossible to even indicate a Continent or Ocean (as some media sources do) where F-G will end up, at this moment.

Most of the predictions favour the 2nd part of Sunday Jan 15th.

Gearing up for the Phobos-Grunt reentry

2012-01-13T10:42:00.002+01:00

We are in for an interesting weekend, as the failed Russian Mars probe Phobos-Grunt is experiencing it's last days of existence. Gradually having come down over the past two months, it is expected to re-enter and burn up (but perhaps not completely) in the Earth atmosphere on Sunday or Monday.

Several days before the re-entry date, it is still not possible (whatever some news outlets erroneously write) to pinpoint when and where it will come down. At the moment of writing (early Friday), the SSC prediction amounts to a still over a day wide window between 15 Jan 02:40 and 16 jan 07:40 UTC. Harro Zimmer's latest prediction is for Jan 15 between 9:00 - 15:00 UTC. Both predictions encompass multiple revolutions around the earth. Please note: all these time windows can still shift, depending on actual developments in space weather (solar activity) and other factors.

Below video has been posted here before, and shows a Fobos-Grunt pass filmed by me from Leiden, the Netherlands, on November 28:

ISS, Prowler, and a flashing Vortex 1 rocket

2012-01-11T16:55:00.003+01:00

Apart from a glimpse through clouds of the ISS on January 2nd (video posted here earlier), I managed to do my first observations of 2012 this weekend, in the evening of January 7 from Leiden and (using a remote telescope in the USA) on January 9.

Conditions were not ideal on January 7th: a lot of moonlight and intermittent clouds. I observed the HEO object USA 200 (08-010A), but due to the moonlight interference the trails were weak (but good enough to get a few positions) and the pictures not pretty.

For the night of January 8-9, I scheduled a few observations on a "remote" telescope, the 61-cm F10 Cassegrain of SSON in California. Target was Prowler (90-097E), an enigmatic object discussed here earlier.

click image to enlarge

The image series on Prowler (I always take a series of at least three images at minute intervals, in case the object is a bit off from predictions) contained a flashing stray.

This turned out to be a classified object as well: Vortex 1r, the r/b from the Vortex 1 launch (78-058B). This rocket stage is clearly tumbling or spinning, as attested by a quite regular flash pattern:

click image and diagram to enlarge

The main flashes are 2.96 seconds apart, and flanked on each side by slow secondary flashes about 0.47s before and after the sharp main flashes, giving the trail on the image a dash-dotted appearance.

An iPad falling from "Space"?

2012-01-11T13:16:00.001+01:00

The video above is going viral currently, being posted on many news websites, Facebook pages etcetera. It shows an iPad being dropped from a balloon at a large height (100,000 feet or 30 km (19 miles)): and surviving.

The video was released by the G-Form company, to promote it's "extreme sleeve" protective sleeve for tablets.

A few remarks on this video:

1) it does not drop from "Space" or even remotely near-Space, as is claimed.

The international boundary of space is at 100 km (62.5 miles), while the USA (deviating from the rest of the world) maintains their version of the space boundary at 80 km (50 miles).

Hence, with approximately 30 km altitude the iPad is nowhere near Space when it is dropped from the balloon. In fact, some military aircraft can and did fly at this altitude, for example the Lockheed A-12/SR-71 reconnaissance aircraft. This is the edge of airspace, but nowhere near true space.

2) It doesn't make a particularly hard landing

Analysing the above video carefully, one can note that after some intitial tumbling, the iPad stabilizes its orientation, and from a certain point on "falls" with the flat back towards the ground, level with the horizon. This is probably helped by the rigged cylindrical device on the back (the GPS tracker probably) and the metal rod attached to one end (that also holds the camera). The weight and position of these probably helps to stabilize the contraption.

As a result, the iPad falls with the flat underside towards earth, i.e. maximizing it's airdrag. This slows the iPad's fall, it basically starts to develop some lift and acts like a wing. A good analogue is a falling leaf. It is no longer truely falling: it is rather gliding.

Look at the screenshots below: this shows the stable attitude of the contraption. Look especially at the third screenshot, which shows the iPad just a fraction of a second before ground impact.

As can be seen in picture 3, details of the ground surface (pebbles, plant stems) are not smeared at all in this single frame. Had the iPad hit earth at large speed, there would have been smearing and not this much detail visible in a single frame.

The fact that all this detail is visible and hardly smeared, simply and undeniably points out that the iPad did not hit earth surface with high velocity. It shows that the iPad in reality glided down at relatively low speed, a speed of at best a few meters/second, similar to a parachute drop.

That is hardly a "hard landing" at all! It underlines that the iPad is gliding down gently, rather than making a true impact. The conspicuous lack of an impact pit is also a sign.

It should be noted that the final part of the video with the landing appears to be sped-up, compressing a longer timespan in just a few seconds. Look for example at the fast movement of the aircraft contrail in the sky just after landing. This speeding-up of the video aids to give the impression of a "hard" landing, while in reality it was a quite gentle landing.

So: this video is not entirely what it purports to be. Yes, the iPad makes an impressive drop from a high altitude (but not from "near-Space" or "Space"). But no, it does not survive solely because of the protective sleeve. The truth is, that the iPad does not land with high speed at all.

Cloud-hampered ISS pass of January 2nd, and deep twilight pass of January 3rd

2012-01-04T14:05:00.000+01:00

The evening of January 2nd started clear, so I set up the video to film another pass (17:01 UTC) of the International Space Station (ISS) which currently has the Dutch astronaut André Kuipers on board.

Unfortunately, an episode with many clouds commenced just before the pass. I managed to film glimpses of the ISS through gaps in the cloud cover.

Very frustratingly, it was completely clear again 10 minutes after the pass.

On January 3rd, it was clear. ISS made a pass in very deep twilight (16:04 UTC), with the sun at an altitude of only -3.5 degrees! Nevertheless, the ISS was well visible by the naked eye, in a bright blue sky with no stars yet.

Summary of 2011 observations

2011-12-31T16:47:00.000+01:00

As the year is closing, it is time for a summary of the observations conducted in 2011.

Compared to the previous two years, 2011 saw slightly more observing nights, a larger number of classified objects tracked, but a slightly lower number of positional estimates done:

Number of observing nights: 87
Number of obtained positions: 883
Number of classified objects tracked: 43

For 2009 and 2010, this were respectively: 77, 953, 32 and 78, 1084, 39

In the second diagram above, it can clearly be seen that the spring and late summer were very good (many clear nights), while winter, and especially December, were very poor.

The following tables give a summary of the objects observed (with the "obs" column refering to the number of positions obtained on the object):

(click tables to enlarge)

Just for fun, I plotted all obtained positions on an RA/DEC map:

click diagram to enlarge

New at SatTrackCam in 2011:

2011 saw several new additions to the equipment:

New lenses - new lenses added to the repertoire were the very fine SamYang f1.4/85mm and a Canon EF 2.0/35 mm. The SamYang allowed to target fainter objects in LEO and MEO, going clearly deeper than the EF 2.5/50 mm normally used on brighter objects in LEO. It's FOV is still large enough to capture full trails.
The Canon EF 2.0/35 was added to target fast moving objects in LEO such as objects near decay, Soyuz and Progress, and Keyholes in perigee passes. It has a similar aperture as the 50mm lens but a wider FOV.

Video - Video finally did it's entry at SatTrakCam Leiden in late 2011. The equipment consists of a sensitive WATEC 902H camera that can be equiped with a number of lenses (including the above mentioned Canon EF 2.0/35 and the SamYang 1.4/85). A GPSboxSprite2 time inserter from BlackBoxCamera in the UK is used for the imprint of accurate time signals, and the video feed is recorded on a HDD recorder.

Remote telescope - I have used remote rentable telescopes for some time for my work on asteroids. Starting mid-2011, I am also using them on satellites. The telescopes used are part of the SSON network and consist of a 37-cm and 61-cm Cassegrain located in California and Arizona. These received COSPAR station codes 8231 (Winer obs, MPC code 597) and 8438 (Sierra Stars obs, MPC code G68). I use them to target geostationary satellites visible from the western part of the USA. Two notable targets repeatedly imaged were the new SBIRS Geo 1 (11-019A) and the enigmatic Prowler (90-097E).

Observational highlights:

A few observational and other highlights of 2011:

Nanosail-D - This experimental NASA solar sail put on a fine show during late spring and summer. A study was made of the brightness variation of this object. See various posts here.

The last Space Shuttle missions - The truely last one was not observed, but the last flight of Discovery was imaged several times.

Spectacular IGS 1B flare - IGS 1B is a Japanese spy satellite that failed in 2007, will reenter in 2012-2013 and probably still has some fuel onboard. When I posted on the latter on this blog, this generated some interest, even from the White House.
On September 2nd, I observed a brilliant flare produced by this satellite, one of the best satellite flares I have ever seen.

UARS and ROSAT - the uncontrolled reentries of these two satellites generated a lot of attention. ROSAT was actually observed twice by me shortly before its reentry, see here and here.

Fobos-Grunt - This Russian probe launched in November should have gone to Mars and the Martian moon Phobos for a sample return mission. A rocket engine failure however got it stuck in Low Earth Orbit, from which it will reenter mid-January. I observed, photographed and even filmed it a number of times.

Andre Kuipers to the ISS - on December 21st, a Soyuz with Dutch astronaut Andre Kuipers was launched for a six-month mission to the ISS. Just before the end of the year, I finally could see the ISS with Kuipers on board pass over Leiden and film it (between launch on December 21 and the sighting on December 30th, it had been very bad weather).

Andre's Soyuz 3rd stage decay - Due to untimely cloud cover I did not observe this event myself, but was involved in the identification of it. The spectacular decay in the evening of December 24th was seen by many people in the east, central and southern parts of the Netherlands (where it was clear, unlike in Leiden), as well as from Germany and France.
Ralf Vandeberg (B), Josep Remis (F) and me (NL) independantly were the first to identify the slow fragmenting fireball with the Soyuz 3rd stage used in the December 21 lauch to the ISS, disseminating our identifications on mailing lists, twitter and blogs within half an hour after the fireball apparition. Read more here.

Footage of the ISS with Andre Kuipers on board passing over Leiden, 30 December

2011-12-30T20:12:00.002+01:00

The footage above was shot by me this evening (30 December 2011, evening twilight, around 16:38 UTC = 17:38 local time). It shows the International Space Station (ISS) with Dutch astronaut Andre Kuipers on board, passing right over my observatory in Leiden, the Netherlands.

The movie was shot using a sensitive WATEC 902H camera and F1.4/12mm lens (this is not the best of lenses in terms of sharpness, but it has a relatively wide FOV of 30 degrees that suited this case. This lens provides a reasonably good approximation of the typical visual view as well in that the limiting magnitude of the movie is similar to that with the naked eye).

I had actually almost missed this pass, as I was busy with another task and lost track of time. So I had to set up my equipment rather in a hurry, with no time to start up and synchronize the GPS time inserter. As usual (and also because I do not yet ahve a "routine"with this new equipment) I initially had an "issue" in getting an image on the laptop monitor: when I finally had an image and could focus, the ISS was already in the sky, ascending at 45 degrees elevation in the west.The sky was still a bit bright from twilight, and some hazy clouds were in the sky.

The footage picks up the ISS in northern Cygnus, shows the ISS as it ascends and goes through the zenith, passing over Pegasus and into Andromeda and next descends through the triangle towards the east, disappearing behind the roof of the house.

I am happy to have this footage at all, as the weather is abominably bad this month.

Further confusion on Saturday's Soyuz r/b reentry

2011-12-27T17:38:00.000+01:00

I earlier wrote about the confusion reigning in the press concerning the sky event over Europe of last Saturday evening. Initial confusion was over wether it was a meteor, "comet" or (and that was the correct explanation, but many Dutch and German news outlets failed to properly pick that up): the reentry of a Soyuz rocket.

Now a new confusion has arrisen: some news outlets and weblogs, e.g. that of Physorg, mistakenly link the event to last Friday's failed Russian launch of the Meridian satellite. Due to a rocket failure, this never reached earth orbit but crashed in Siberia within minutes after the launch.

As I wrote earlier, what reentered and was seen over France, Germany and the Netherlands last Saturday evening, was the 3rd stage of last Wednesday's Soyuz launch to the ISS.

The confusion probably comes from the fact that both launches used a Soyuz rocket. The failed launch that crashed in Siberia on Friday got some press attention because fragments hit a house in Russia (see a.o. here (English), with pictures of a recovered fuel tank here (Russian)).

But again: that failed launch had nothing to do with Saturdays sky event over Europe. The reentry over Europe was the 3rd stage of the earlier Wednesday launch to the ISS, that included Dutch astronaut Andre Kuipers.

(More on Last Saturday's Soyuz reentry over Europe: here and here)

11-078B Soyuz 3rd stage reentry: answers to some frequently asked questions

2011-12-26T14:49:00.002+01:00

In the wake of the spectacular reentry over NW Europe of the Soyuz 3rd stage 2011-078B on Saturday 24 December 2011, several common questions popped up in comments, e-mails, on Twitter and in newspaper discussions. I will answer a few below.

Frequently Asked Questions:

(Q1): Are these things predictable and who makes such predictions?
(Q2) Does it really take a Soyuz rocket 3rd stage three days to fall back to earth?
(Q3) Why doesn't this happen with each Soyuz launch? Or: why not over the same location on Earth?
(Q4) has anything of the rocket stage survived to earth surface?

Answers:

(Q1): Are these things predictable and who makes such predictions?

(A): It is "sort of" predictable. Using computer models which take into account many factors of influence, one can make a prediction yielding an indication of the time a rocket stage or satellite will re-enter the atmosphere. However, even very close to that actual time of reentry, the uncertainty in these predictions is still very large. Exactly when a rocket stage will start to burn up depends on many factors, including the exact condition of the atmosphere at that moment, the shape of the rocket stage, and whether it is tumbling or not. In practise, this turns out to be very difficult to model, even with the best computer models.

Several organisations and individuals do such predictions (and you can even find software for it on the internet). However, one of the most authoritive sources of such predictions is USSTRATCOM, the American military organisation that tracks manmade objects in space (many people think NASA does that job. But that is incorrect: it is USSTRATCOM, better known as 'NORAD'). They publish these predictions as 'TIP' messages. Their first prediction is published 2 months in advance. These still have a very large uncertainty (think of: weeks). In the days close to decay, they publish new estimates as new TIP messages that gradually become more exact. But even these can have uncertainties of several hours, even for predictions made on the day of the reentry itself.

For example, the last pre-reentry TIP message issued only 2 hours before the Soyuz 3rd stage came down, still had an uncertainty window of six hours.....

Once an object has reentered, USSTRATCOM does a post-analysis of the last orbital information, and publishes a "final' TIP message mentioning when and where the object came down (so this is done "after the fact"). These can be (but are not always, as it depends on how well the object was tracked during it's last hours of existence) very accurate. Sometimes, as was the case with this reentry of the Soyuz 3rd stage, they provide a time with an uncertainty of only minutes, plus a quite accurate position. In other cases, where less recent tracking data is available, the final uncertainty is much larger.

Note that a re-entering satellite or rocket booster has a speed of 7.5 km per second (4.7 miles per second)! So even if the predicted time has an uncertainty of just 15 minutes, this amounts to an uncertainty of 13,500 km (8,400 miles) in the position of the object when it reenters! This is why it is impossible to pinpoint the expected point of re-entry beforehand, when it is not a "controlled" re-entry. (in a "controlled" re-entry, the satellite operators send a command to the satellite to make a rocket burn at a precise time, kicking it down over a designated spot, usually the Pacific ocean. This Soyuz reentry was however not such a "controlled" reentry).

Many people mistakenly think that in this day and age of supercomputers, scientists (or the military) can predict everything. In reality, satellite/rocket reentries like this are so complex that even the best computer models can only give rough indications untill just minutes before the actual re-entry.

(Q2) Does it really take a Soyuz rocket 3rd stage three days to fall back to earth?

(A) Yes, it does. That last rocket stage is jettisoned that high above earth surface, that it does not just rapidly fall back on a ballistic trajectory (such as the 1st and 2nd stages do) but actually reaches Low Earth Orbit, and stays in orbit around the earth for several days. In effect, it becomes a satellite for a while in a very low orbit around Earth. Under influence of gravity and drag from the outer atmosphere, the orbit slowly evolves and becomes smaller and smaller. On the first day only gradually, but as it slowly comes down, this gradually goes faster and faster.

The influence of our atmosphere reaches several hundreds of kilometers up: even the International Space Station experiences some atmospheric drag, and would fall down within a year if its orbit was not regurlarly raised using the rocket engines of the Progress spacecraft docked to the ISS.

It takes about 3-4 days for a Soyuz 3rd stage from a launch to the ISS to come down. The exact amount of time is variable and different in each new case, as it depends on many factors. Our atmosphere is variable in extent and density, notably under the influence of solar activity. When the sun is active and many charged particles from solar outbursts reach earth, these interact with our atmosphere and the atmosphere slightly expands as a result of this. This means that objects at the altitude of the Space Station and below that (such as the Soyuz rocket stage) will experience a "thicker atmosphere", i.e. more drag from the atmosphere's outermost layers, and as a result they will come down faster. When it reaches at altitude of only 120 km (75 miles) it goes very quick: within minutes the rocket stage has dropped tens of kilometers, slowed down considerably, and finaly plunges straight down from that moment onwards.

The exact moment this happens, is highly dependant on these variations in extend of our atmosphere due to variations in solar activity. This is another reason why a satellite or rocket re-entry is so difficult to predict: one short but intense outburst occuring on the sun will next make a rocket stage fall back much quicker than expected.

Below diagram shows the orbital evolution of the Soyuz 3rd rocket stage that decayed last Saturday. It had to make 52 full orbits (full circles) around the Earth before it burned up. It's orbit was a bit "eccentric", which means that it was not a perfect circle but an ellipse. So on each revolution around the earth, there is a point where it is a bit higher above earth (called the "apogee") and a point where it is closest to the earth (called "perigee"). In the diagram, the values for these altitudes have been plotted as a red and blue line. Note how fast these altitudes change in the final hours before re-entry.

(Q3) Why doesn't this happen with each Soyuz launch? Or: why not over the same location on Earth?

(A) It does happen with each Soyuz launch to the ISS. The Soyuz 3rd stage always comes down some 3-4 days after the launch.

That reentry however is never over the same location on earth. The reasons for this, have already been outlined as part of the answer to question (2) above. An important factor of influence on how quickly a rocket stage comes down, is the variable earth's atmosphere, under influence of variability in solar activity. These factors are different for each new case. This is why the 3rd stages of Soyuz launches to the ISS never fall down near the same spot twice.

(Q4) has anything of the rocket stage survived to earth surface?

(A) Not that we so far know of. Usually, the rocket stage almost completely burns up in the atmosphere. Sometimes, a few smaller bits survive (quite often spherical fuel tanks). For example, an object that is likely a rocket fuel tank came down in Namibia in November and might be part of a rocket stage used in a Russian November launch to the International Space Station.

[Updated] Breaking News: Decay of Soyuz r/b stage from André Kuipers' launch to ISS observed from the Netherlands!

2011-12-24T18:58:00.000+01:00

UPDATE - the final TIP for Soyuz r/b 38037 / 2011-078B has been released by USSTRATCOM near 18h GMT and it indeed shows that this was the Soyuz r/b: reentry time is quoted as 16:25 +/- 1 minute GMT at 49 deg N, 7 deg E. This fits the observations well.

In the Dutch press, there meanwhile appears to be a lot of confusion. The Dutch National Police claims that they talked to "NASA" who apparently said it was a "meteor" (or "comet"). So THAT is widely claimed in the press now, to the point of calling the identification with the Soyuz 3rd stage "speculation". Which it is not: it is based on factual data and now clearly confirmed by the USSTRATCOM TIP message. What more do you want?!

I have no idea to whom (or even where: NASA is big...) the Police spoke, but for all things it could have been the JPL janitor....

At any rate: appart from my analysis below (which is already clear), the USSTRATCOM TIP message mentioned above makes unambiguously clear that this was the Soyuz 3rd stage.

Note that to access the USSTRATCOM TIP message via the link above you need an approved account. USSTRATCOM is the US military Command responsible for tracking manmade objects in space, and perhaps better known under their former name NORAD.

- end of update

Multiple reports are coming in, among others by experienced Dutch meteor observers Carl Johannink (Gronau) and Arnold Tukkers (Denekamp), of a bright and very slow fragmenting object seen low in the west-southwest near Venus at 16:26 UTC, 24 December.

From the descriptions it clearly was a reentry of an artificial object (space junk), as the event was too long in duration and too slow to be a meteoric fireball.

And it was not "just" a random bit of space debris, it turns out:

The observations fit with 2011-078B (#38037), the last stage of the Soyuz rocket that brought Dutch astronaut Andre Kuipers up to the ISS earlier this week. It was already predicted to decay near this moment by USSTRATCOM.

Below is the predicted trajectory of the Soyuz 3rd stage for the Gronau/Enschede area (and below that, the ground trajectory). It is based on an orbit with an epoch near noon of 24 December (epoch 11358.49032868. Source: USSTRATCOM), so a few hours old, which will introduce some minor discrepancies (a few seconds in time). But it fits the descriptions very well in terms of time and trajectory in the sky.

click images to enlarge

Some quickly translated descriptions by two experienced Dutch meteor observers (compare to the sky trajectory map above for their area):

Arnold Tukkers, Denekamp:

At 17:26 CET (=16:26 UTC) I looked out of the window and saw a strange phenomena just above the rooftops behind us. It looked like a very, very slow meteor fragmented in several pieces. Like Peekskill but less bright.
Multiple fragments. Beacuse it was so low in the sky, I walked upstairs and could still see the last part from the bedroom window. So it at least took 20 seconds. [...]
What a sight! Trajectory for me (did not see initial part) southwest-southeast. Altitude maximum 20 degrees. Colour brown-red.

Carl Johannink, Gronau:

Just was looking at Venus in evening twilight.
Left of it an object appeared from behind a cloud that I first thought to be an aircraft, but next I found something was not right. The thing sometimes brightened and became fuzzy, trailing a circa 8 degree long tail. Maximum brightness about -4.
The object roughly moved from SSW to SE at an elevation of about 15 degrees. The whole phenomena took over half a minute.

To see the second part of the trajectory I had to walk to a different room. Called in Elisabeth, together we saw the object fragment into pieces (each individual piece about mag. 0 to +1) and then fade out.

The whole event looked much alike to the New Years Eve satellite decay of 1978, albeit being somewhat less bright.

Update:
A number of video's from Germany have surfaced which likely show the event. Here are a few:
video 1
video 2
Video 3 (on the Bad Astronomer's blog)
Video 4
Video 5

FAQ

Read the answers to Frequently Asked Questions for this reentry case I published later here.

Observing Fobos-Grunt on 30 November

2011-11-30T19:54:00.001+01:00

It was clear this evening, and the Russian Mars/Phobos probe Fobos-Grunt (2011-065A) stranded in Low Earth Orbit made two visible passes which I both observed.

The first pass was in deep twilight, 16:08 UT with the sun only 5 degrees below the horizon. The sky was still bright blue and only the brightest stars (Altair and brighter) were visible. Nevertheless, Fobos-Grunt was easily visible by the naked eye, becoming clearly brighter than Altair around and after culmination at 45 degrees elevation in the south. It was very fast and showed no sign of brightness variation. A very fine view!

It made a second pass at 17:40 UT, plunging into the earth shadow at 25 degrees due west. I captured it on a photograph when it was at 20 degrees elevation, close to alpha Oph (brightest star in the image):

click image to enlarge

The lens used was the SamYang 1.4/85 mm and because of the low elevation and city environment, I kept the exposure short to 5 seconds. Due to a different phase angle compared to the earlier pass, the space-probe was faint, near +4.

I also tried to video it again like two nights before (see video in my previous post). This time less succesful, due to a case of Murphy. A cable came lose just at the moment supreme, and in the haste to attach it again, the camera was moved and then pointed to the wrong star.....

Footage of a Fobos-Grunt pass

2011-11-28T21:11:00.001+01:00

The footage above was shot by me this evening, and shows the Russian space probe Fobos-Grunt (aka Phobos-Grunt or Phobos-Soil), 2011-065A.

Fobos-Grunt was supposed to go to the Martian moon Phobos for a sample return mission. Instead it got stuck in a Low Earth Orbit, due to a rocket engine malfunction. It is now expected to re-enter into the earth atmosphere early to mid January.

This footage was shot from my girlfriend's appartment at the second floor of our appartment building: only there was I able to point low enough in the sky. The footage shows the space-probe at an elevation of less than 15 degrees over the western horizon. It enters earth shadow at the end of the 50 second clip.

NOSS 3-1 A & C no longer a pair, and Lacrosse 3 is missing

2011-11-20T13:32:00.001+01:00

On November 14th and 15th, Alan Figer from France first noted that one of the objects of the NOSS 3-1 pair (2001-040 A & C) was missing. Following up on his message, I could confirm this the next evening, using photography and video. Only one object instead of the usual close pair of two was visible:

Above is the video footage that was shot by me. What turns out to be the A-component can be seen crossing Lyra (bright star is Vega. The glow in the lower left corner is from a nearby lamp), but no C component is to be seen in this video segment (nor was it for one minute before and 3 minutes after this segment). Next, Derek Breit missed it as well in a window of 8 minutes centered on the A object pass, and so did Brad Young.

Over the past few days, two possible obervations have been made of the missing C-object, now well away from the A object, by Brad Young and Bill Arnold.

The break-up of the NOSS 3-1 pair probably means it had reached end of mission. It is interesting to see that some of the older NOSS pairs (and one trio) do still maintain their pair bonding though..

Lacrosse 3 has gone missing - perhaps deorbitted

Another satellite, the 14 year old SAR satellite Lacrosse 3 (1997-064A) has gone missing in a more serious way. It has not been seen since early October. Several observers including me and Pierre Neirinck have done plane searches but so far, it hasn't been recovered. So it has either manoeuvered into a completely different orbit, or has been de-orbitted. If the latter is true, this possible de-orbit comes half a year after the de-orbit of Lacrosse 2 late March 2011. It leaves two remaining Lacrosses in orbit (Lacrosse 4 and 5).

The Lacrosse 5 "disappearance trick" captured on video

2011-11-13T17:21:00.001+01:00

Note: the video below was featured (with my permission) on Spaceweather.com. Unfortunately, it was initially suggested there (and this definitely did not come from me) that the discussed "disappearance trick" is a deliberate "stealth" feature of this satellite.

It almost certainly is not: it is something brough about by accident from something specific in the satellite design.

I also want to make clear, as it kept popping up in the YouTube comments (which I have now disabled), that this is not the moment the satellite disappears in earth shadow! The drop in magnitude happened at 17:35:20 UTC: shadow entry was much later, 17:38:55 UTC.

The video above was shot by me Friday evening (11 Nov). It shows Lacrosse 5 (2005-016A), the latest of the Lacrosse SAR satellites. It was launched in 2005. In the movie, it is doing it's infamous "disappearance trick" (also note the old Russian rocket stage visible in the second part of the footage).

The brightness behaviour of this satellite is different from that of the previous Lacrosse satellites. Apart from that it is brighter overall and a bit yellowish in colour (the others are distinctly orange-reddish), it shows a variable brightness behaviour that the other Lacrosse satellites do not show (or at least not to this extreme extend).

Lacrosse 5 can sometimes drop several magnitudes in brightness, typically from +1 (easy naked eye) to +5 or +6 (naked eye invisibility or near-invisibility), in a matter of seconds.

After observing this a couple of times, I coined it the "disappearance trick", a term that has stuck in the amateur satellite observer's community.

While many satellites can flare briefly (and the Lacrosses do), this opposite effect of one suddenly dropping in brightness other than due to normal phase angle changes or entry into earth shadow (which is not the case here!!!), is not quite common. And Lacrosse 5 does it that frequently, that it stands out.

Normally, when a satellite or spent rocket stage shows sudden changes in brightness, it is due to either:

a) the satellite entering earth shadow;
b) the satellite is tumbling.

Both are not the case here. These "disappearance tricks" of Lacrosse 5 happen well before the point of shadow entry. In addition, the behaviour is not the typical "flashing" behaviour of a tumbling or spinning satellite. There is no periodicity, and the drop in brightness happens after a long period of stable brightness.

The behaviour is interesting, because the sister ships of Lacrosse 5 (the other Lacrosses) do not typically show this behaviour. The implication is, that Lacrosse 5 is different in design than Lacrosses 1 to 4.

I have photographically documented the phenomena several times, including brightness curves (see here, and a comparison of several curves showing the phenomena here, featuring the comparative diagram shown below).

click diagram to enlarge

Philip Masding has been documenting the phenomena as well, his results can be seen here. His curves also show, and I have seen this happen as well, that Lacrosse 5 can sometimes "re-appear" (and, as I have seen occasionally, next "disappear" again...).

One point is, that we so far cannot find a clear pattern in this all. The satellite does not seem to do this at specific phase angles for example.

We are still at a loss to explain this behaviour. Please note: we don't think it is an intentional "stealth" characteristic. Yet it must have something to do with the satellite design or operation.

Is it a matter of strongly differing reflectance properties of the satellite body with illumination angle? Is it some brightly reflecting appendage on the satellite disappearing from view? Is it a dark appendage on the satellite starting to block view of the illuminated satellite body, or casting a shadow on it? Is it due to some moving part of the satellite, e.g. a moving dish antenna?

We simply do not know. And it is giving us a nice puzzle.

The photograph below, taken in addition to the video footage above, shows Lacrosse 5 in the bright phase of Friday's trajectory.

click image to enlarge

Apart from Lacrosse 5, I observed a couple of other satellites last Friday, including the NOSS 3-5 duo (11-014A & B) and USA 32 (88-078A)

If rescue fails, Fobos-Grunt will reenter soon

2011-11-11T12:42:00.001+01:00

As new attempts to contact the probe failed, the future is looking increasingly grim for Fobos-Grunt (aka "Phobos-Grunt" and "Phobos-SOIL"), the Russian space probe launched on 8 November that should have gone to the Martian moon Phobos for a sample return mission, but instead got stuck in Low Earth Orbit.

The probe is currently stuck in a very low orbit measuring 207 x 339 kilometer after it's propulsion unit apparently failed, failing to lift it into a GTO (and from there an interplanetary trajectory):

If the probe isn't revived in due time - and the Russsian operators are still frantically trying to do so - it is doomed. With an orbit at this low an altitude, it is a short matter of time before it comes down again - another case of an imminent uncontrolled reentry of a very large satellite (over 13 metric tons, including the fuel). How much fuel is onboard is not clear to me: different media sources quote quite different amounts, but all amounts quoted are in terms of several tons, with several sources settling for 7 tons (see also here).
As pointed out here by Anatoly Zak, seizable chunks of the probe could survive reentry, and survival is certainly expected for the actual Fobos sample return capsule (which was designed for reentry).

Reentry estimates

Estimates of when Fobos-Grunt will come down are a bit complicated. Ted Molczan has noted that over the past day, the orbital evolution was unusual - Ted points out that if the last two orbit releases are not faulty (a possibility), it means that either the probe is manoeuvering (which from all the negative statements by the Russians in the press seems unlikely) or - more likely - has started to vent fuel since yesterday. As a result, it might have gotten a very mild orbital boost (the leaking fuel acts like a small rocket engine).

Before this unusual behaviour started, orbital elements 11314.14749491 to 11314.77184893 and Alan Pickup's SatEvo software with current solar activity levels suggested a nominal reentry time no later than early January 2012. SSC meanwhile predicts reentry for November 26th, 2011. The current unusual orbital evolution - if real - might change things a bit, but eventually it will come down.

This means it will likely come down somewhere over the next few weeks or months if the operators cannot revive it over the next two weeks. With an orbital inclination of 51.4 degrees, it can come down anywhere between 51 N and 51 S latitude.

There has been a call out to observers to observe the probe - it's brightness behaviour can yield clues as to whether it is starting to tumble, e.g. because of the suspected fuel venting. So far, observations by Brad Young and Michael Murphy from the US suggest the probe is stable in brightness with no sign of tumbling (see here and here).

Unfortunately, the probe is currently not visible from NW Europe where I am located: it makes passes near midnight, completely in shadow.

First light of my WATEC camera - footage of Lacrosse 5 and the NOSS 3-4 duo

2011-11-11T11:32:00.001+01:00

For quite a while, I have had a wish to add video to my observing techniques. That moment is now there.

During last October's Draconid meteor campaign, I was introduced to working with WATEC 902H camera's (see my previous post here), and discovered it was not that technically complicated after all. So when I saw one offered for a very good price in a clearance sale in October, I bought one.

The WATEC 902H is a sensitive surveillance camera, which is able to film stars - and satellites- in the night sky. It is small (fits in the palm of a hand).

I still need to add a GPS time inserter (it has been ordered already) for adding precision timing to the video frames. Once that is done, the system is complete.

Meanwhile, I did some test imaging when it briefly cleared last Wednesday evening. Conditions were not optimal: moonlight and a bit of haze. Below are two results, both movies made using a Canon EF 2.0/35mm lens attached to the camera and in both cases the opening shot shows the "dipper" of Ursa minor, with the brightest stars being beta and gamma Umi.

The first movie shows Lacrosse 5 (2005-016A), at one point doing its "disappearance trick":

The next movie shows the NOSS 3-4 duo (2007-027A & C):

The first experiments were a bit more problematic than anticipated. Initially, I tried to feed the video signal from the camera directly into the laptop (and record using the laptop) using an EasyCap capturing device. That turned out to not work that well. My laptop is old and apparently too slow, and too many frames were dropped resulting in movies that did not flow well.

On the advice of Scott Campbell, Kevin Fetter and Greg Roberts, I then added a HDD recorder to the equipment, recording with this device rather than with the laptop. That turns out to work fine, and resulted in the footage above (note: the original movie files are a bit better in quality than these YouTube versions).

I do not intend for video to replace photography at my observatory: I intend it as an augmentation to the photography. Every once in a while, it is nice to have actual moving footage.

Both techniques have their pro's and con's. Video has accurate timing but low astrometric accuracy (due to the low resolution of the imagery). Photography has a high astrometric accuracy, but less timing accuracy (although by now, after much practise my time residuals are usually well below 0.1s). I think the pro's and con's of both techniques largely even out. One pro point of photography, is that it doesn't need a power supply - meaning you can be more mobile.

Apart from using it on satellites, I also intend to employ the WATEC for meteor surveillance (Peter Jenniskens' CAMS system, if I can get the software to work here, which so far turned out to be problematic) and for observing asteroid occultations.

Another close encounter of a rocky kind....: 2005 YU55

2011-11-09T17:29:00.002+01:00

Half a year after the close approach of asteroid 2011 MD (see my images here and here), another one whizzed by the Earth last night. It was 2005 YU55, a 400-meter wide asteroid discovered in 2005 by Spacewatch. It came to within 0.85 lunar distances at 23:28 UT (Nov 8, 2011), with a maximum brightness near +11.

click image to enlarge

Four hours after closest approach, I made the image above, using a "remote" 61-cm F/10 Cassegrain telescope at Sierra Stars Observatory (MPC G68). It is a 30 second exposure starting at 03:21:41 UT (9 Nov 2011), during which the asteroid (moving from right to left) has trailed considerably.

Astrometry from my images has been included in MPEC 2011-V34 (the G68 observations at

09.11922, 09.14006 and 09.32778).

Observing Geostationary Satellites from Leiden and Arizona

2011-10-26T14:09:00.000+02:00

While the focus was on LEO and HEO satellites earlier in October, I primarily targetted Geostationary satellites last week. Both from my own locality with my own equipment, as well as by means of a "remote" telescope in Arizona.

The two images below were taken from Leiden (the Netherlands) in the early evening of October 23, using my own equipment (Canon EOS 450D + Carl Zeiss Jena Sonnar MC 2.8/180mm).

They show the enigmatic, frequently re-locating PAN satellite (09-047A: see Dwayne Day's article here) and the SIGINT (eavesdropping) Mentor 4 (USA 202) satellite (09-001A), as well as a few commercial geostationary telecom objects: Hellas-sat 2 (03-020A), Thuraya 2 (03-026A) and Paksat 1R (11-042A).

click images to enlarge

As can be seen, PAN and Hellas-sat 2 are a very close pair now, so close that I am not actually 100% sure which one is which (the westernmost one or rightmost one is likely PAN). As can be seen in comparison to this post from May, it has relocated again, from 45.0 to 38.9 E - it did so in July, when I was on hollidays.

Somewhat earlier the same week, when the sky in Leiden was overcast, I took refuge by hiring a "remote" telescope again. This time not the 61-cm of SSON, but the 37-cm Cassegrain of Winer Observatory (MPC 857) in Sonoita, Arizona, USA. While a smaller instrument, this telescope has a larger FOV which is good if the satellite is a bit off from predictions, and allows te satellite to be captured on more than one image when a 3-image run is done. Also, it is cheaper to rent.

Targets were two "usual suspects": the enigmatic Prowler (90-097E: see story and links in my previous post here) on October 17 and 21 and the SBIRS-GEO 1 (11-019A) on October 21:

click images to enlarge

Note: because the telescope follows the stars, the satellites become trailed, unlike the images shot from Leiden which are from a stationary tripod (hence the stars trail, but the satellites not).

A few non-geostationary satellites were tracked the past two weeks as well. They include the STSS Demo 1 & 2 (09-052 A & B) and the USA 89 r/b (92-086C) on October 22, and the HEO ELINT & SBIRS platform USA 184 (06-027A) on October 15.

ROSAT down over the Indian Ocean [RENEWED UPDATE]

2011-10-23T14:04:00.000+02:00

ROSAT is no more.....according to a TIP bulletin by SSC issued at 03:41 UTC, it reentered at 1:50 UTC +/- 7 minutes, placing it over the Indian Ocean (and far away from any eyewitnesses, bar maybe some ships and maybe Ceylon, Sumatra and Birma/Malaysia/S-China if it survived into the second half of the given window: and of course the US tracking facility at Diego Garcia).

See update 2 below for latest map version (update 1 below now deprecated)

update 1 - deprecated.
[Below two map shows the final orbit and (thick red line) the reentry windows according two assessments:
- The first is with the last available TLE (issued over a day before the reentry) propagated with SatEvo.
- The second, is made by adjusting the time (by about 5 minutes) so that the satellite position matches the nominal position for the reentry given by SSC in the TIP bulletin: 7 N, 90 E]

click maps to enlarge

[As can be seen there is some difference between these two. This is the result of there currently being no recent TLE available: the last available TLE dates 24 hours before the reentry. In the 24 hours between that last issued TLE and reentry, the orbit evolved fast. Without the availability of more recent elements, it is difficult to assess where the satellite exactly was along its orbit. That uncertainty is no more than a few minutes in time, but that amounts to over 2000 km in position....]

UPDATE 2: SSC released a new tle, with an epoch dating to two hours before the decay (about 1.5 revolutions). This allows this map to be created, which closely tallies with map 2 above:

click map to enlarge

It shows the difference a new TLE much closer in time to the decay makes, with regard to locating the satellite in its final moments....

(note: thanks to Daniel Fischer for inquiring about the differences between my map and Simone Corbellini's map, and to Simone for communications on the why of the time offset)

ROSAT reentry update (2)

2011-10-22T18:02:00.000+02:00

Update to my previous post: Space-Track (SSC) finally released a new elset, 11294.85810509, which is still and "old" elset (almost a day old). And they released a new TIP with a new reentry prediction.

The new TIP gives this prediction:
Space-Track (SSC): 23 Oct, 02:34 UTC +/- 7 hrs

Based on the new TLE, independant analyst Harro Zimmer now provides the following prediction:
Harro Zimmer: 23 Oct, 04:17 UTC +/- 4 hrs

Other independant analysts have not updated yet (see my previous post for these values). I did a run of SatEvo with the newly released TLE and the current F10.7 cm solar flux, and get, for what it's worth, a projected time of 10:20 UTC (23 Oct) +/- 5 hrs. That seems a bit late compared to the SSC and Zimmer estimates (although the uncertainty windows of course overlap).

ROSAT reentry update

2011-10-22T14:32:00.000+02:00

New independent updates on the projected moment of the ROSAT reentry are hampered by the fact that no new orbital elements have been released for 1.5 days now - the last elset released being elset 11294.06213865 (epoch time 21 Oct 01:29:29 UTC) as of this moment (22 Oct 12:10 UTC).

Meanwhile, here is a summary of the latest available predictions at this moment of writing:
Space-Track (SSC): 23 Oct, 01:31 UTC +/- 14 hrs
Aerospace Corp: 23 Oct, 13:24 UTC +/- 16 hrs
Harro Zimmer: 23 Oct, 05:33 UTC +/- 6 hrs
Ted Molczan (using SatEvo): 23 Oct, 05:00 +/- 10 hrs
T.S. Kelso: 23 Oct, 03:15 UTC (uncertainty not listed)
DLR: 23 Oct, ~3h UTC +/- 9hrs (midtime from window given)

The FAA has realeased a NOTAM warning for the reentry:

!FDC 1/9172 FDC SPECIAL NOTICE .. ..........EFFECTIVE IMMEDIATELY UNTIL 1110252359 UTC. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY OCCUR DUE TO REENTRY OF THE SATELLITE ROSAT INTO THE EARTH'S ATMOSPHERE. THE FEDERAL AVIATION ADMINISTRATION (FAA) IS WORKING WITH THE DEPARTMENT OF DEFENSE (DOD) AND THE NATIONAL AERONAUTICS AND SPACE ADMINISTRATION (NASA) TO ENSURE THAT THE MOST CURRENT RE-ENTRY INFORMATION IS PROVIDED TO OPERATORS AS QUICKLY AS POSSIBLE. FURTHER NOTAMS WILL BE ISSUED IF SPECIFIC INFORMATION BECOMES AVAILABLE INDICATING A UNITED STATES (US) AIRSPACE IMPACT. IN THE INTEREST OF FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY AND INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. THE DOMESTIC EVENTS NETWORK /DEN/ TELEPHONE 202-493-5107, IS THE FAA COORDINATION FACILITY

Gearing up for ROSAT's re-entry, and an older observation of a Breeze-M tank near M31

2011-10-21T13:11:00.001+02:00

Shortly after UARS, another satellite about to reenter is in the news: ROSAT. I last observed and photographed it about a week ago (see here and here) - since then, passes have become unfavourable for the Netherlands.

In an interesting twist, Sky & Telescope's J. Kelly Beatty reports that DLR and ESA sources confirmed to him that they expect the entire telescope mirror array - which weights 1.6 tons! - to survive reentry, impacting intact!

Various modellers now project the reentry to occur on October 23rd. Here is a short list of what various sources currently predict [editted 12:10 UTC, Oct 21, with latest Molczan update):

Space-Track (SSC): 23 Oct, 05:49 UTC (+/- 24 hrs)
Harro Zimmer: 23 Oct, 05:03 UTC (+/- 48 hrs)
Ted Molczan (using SatEvo): 23 Oct, 05:00 UTC (+/- 10 hrs) [editted]
Aerospace Corp.: 23 Oct, 13:24 UTC (+/- 16 hrs)

Since Ted uses the same software I used for my UARS predictions, and hence our results will be similar, I will not put forward my own predictions here but refer to Ted's.

A Breeze-M near M31, the Andromeda nebula

In my post of October 2nd, I featured an image I took on 29 September of a Russian Proton upper stage Breeze-M tank near the trail of USA 129. I wrote that:

These pieces of Russian space debris pop up more often on my images lately. They are the jettisonable torroidal (doughnut-shaped) fuel tanks of a Breeze-M, the upper stage of a Proton M. There are now over 40 of these spent empty tanks in space, often in highly elliptic orbits representative of a geostationary transfer.

Just a few days later, on October 2nd, I took advantage of clear skies to image M31, the Andromeda galaxy. The camera (Canon EOS 450D) with the Samyang 1.4/85mm lens was piggybacked on a Meade ETX-70 in order to use the telescope drive to follow the stars. A long series of 10 second images was taken.

Several satellites showed up on the image series, including a Breeze-M tank again, this time 2006-056B:

click image to enlarge

Here is the final image of M31, a stack of 105 individual 10 second images:

click image to enlarge

Given that this image was taken from a town center with modest equipment, I am quite happy with it! If you compare it to a single frame image (above) it shows the strong improvement in signal-to-noise ratio that comes from stacking images.The two satellite galaxies come out much better, and so does a glimpse of the spiral structure and dust bands in the Andromeda galaxy.

OT - 1883 Zacatecas observation of objects before sun were not 12P/Pons-Brooks fragments

2011-10-17T11:56:00.004+02:00

A rather weird story has been posted here on the Technology Review website, based on this paper posted on Arxiv.org.

In it, Manterola et al. discuss an observation from 1883 by Jose A. y Bonilla from the Astronomical Observatory of Zacatecas, Mexico. On August 12th and 13th, he observed objects passing in front of the sun during telescopic solar observations. These objects were "misty" (= unsharp?) and crossed the sun in about 1 to 1/3 seconds of time. They were not seen during simultanious observations from other Mexican observatories. The observations were published in L'Astronomy in 1886, and the editors put it down to dust in the telescope system, birds or insects crossing the FOV.

Manterola et al. now make an argument that it were cometary fragments passing as close as 800 to 6000 kilometers (!) from earth, suggesting Earth narrowly escaped a shower of cometary fragment impacts. They also argue that it were fragments of comet 12P/Pons-Brooks.

The latter theory can be quickly falsified. The 1883 nodes of the orbit of comet 12P/Pons-Brooks were at solar longitude 255.8 deg (ascending node) and 75.9 deg (descending node), corresponding to December 6 and June 5. The latter (descending node) is far away from earth, beyond Saturn's orbit. The ascending node is closer, but still closer to the orbit of Venus than to the orbit of Earth.

This means that the earth only comes (not particularly) close to the cometary orbit near this date, and hence any fragments in similar orbits can only come close to earth on this date: December 6. Not on August 12-13, the date of Bonilla's observations.

The diagrams below show how the earth is nowhere near 12P/Pons-Brooks' orbit on August 12-13, passing closest on December 5-7 instead (with the comet orbit at 0.2 AU minimum distance from Earth orbit: closer to Venus than to Earth):

click diagrams to enlarge

It should also be noted that the MOID between the Earth orbit and the comet's orbit is not particularly close (minimum 0.2 AU). Hence, it does not tally. These cannot realistically have been 12P/Pons-Brooks fragments.

The whole story seems far-fetched and very unlikely.

The "fuzzy" character of what Bonilla descibes to me suggest out-of-focus objects, i.e. close by (with the telecope focussed on the sun), well within the Earth atmosphere and most likely within the telescope system. The "dark before sun disc, bright outside disc" is very odd, especially the latter - objects need to be very bright to outshine the sun and (presumably) a solar filter so close by the sun.

OT - Draconid observations from Northern Germany, 8-9 October 2011

2011-10-16T17:19:00.000+02:00

click image to enlarge

16 Draconid meteors photographed between 19:27 and 21:18 UTC, 8 October 2011. Canon EOS 450D + EF 2.0/35mm, 800 ISO, Dunkelsdorf, Germany. Photo by author.

In the evening of October 8-9 2011, the Draconid meteor shower performed a rare meteor outburst. In normal years, hardly any Draconid meteors can be seen. But in 1933, 1946, 1952, 1985 and 1998, short but (very, in the cases of 1933 and 1946) intense outburst were observed. The earth crossed through dust trails left by the parent comet 21P Giacobini-Zinner those years. Zenith Hourly Rates were in the several hundreds in 1985 and 1998, in the thousands in 1933 and 1946.

Last October 8th (2011), the earth was predicted to encounter a dust trail left by the comet in 1900. Predictions for the activity varied, from virtually nil to several hundreds/hour, depending on the modeller and model (see summary in sidebar here).

Several scientific efforts were set up to monitor the event. I joined one of them, a joint effort lead by Peter Jenniskens (SETI/NASA-Ames) in cooperation with the Leibniz-Institut für Atmosphärenphysik (IAP) in Kühlungsborn, Germany (Michael Gerding), and Carl Johannink and me from the Dutch Meteor Society (DMS). Our project was a groundbased part of a wider effort including two aircraft flying with scientific equipment (the Draconid 2011 Multi-Instrument Aircraft Campaign, see here).

Our goal was to do observations that could not be easily done from the aircraft: determine 3D trajectories of meteors in the atmosphere by triangulation of images taken from two locations, in combination with an attempt to detect debris/ionization trails of these same meteors using a LiDAR.

The LiDAR in question, was the LiDAR of the Leibniz-Institut für Atmosphärenphysik (IAP) in Kühlungsborn, a small bathing resort at the Baltic coast of eastern Germany. This part of the observations was done by Dr Michael Gerding of the IAP, who was also our host during the effort. Peter Jenniskens, Carl Johannink and me would employ and operate the multistation video network, using the CAMS system build by Peter and his team at SETI/NASA-Ames (the CAMS project is part of NASA's Planetary Astronomy program).

click images to enlarge

The CAMS systems (4 low-light level video cameras per station) used. Top: the setup at Lebatz station operated by Carl Johannink and the author (DMS). Bottom: the setup at the IAP Kühlungsborn station operated by Peter Jenniskens (left; SETI/NASA-Ames) and Michael Gerding (right, IAP).

Wednesday 5 October

I fetched Peter Jenniskens from Schiphol airport near Amsterdam on Wednesday the 5th. We hauled his equipment (two heavy metal cases, apart from Peter and mine personal luggage) into the train to Enschede in the eastern Netherlands, where Carl fetched us and drove us the few remaining kilometers to Gronau, just over the Dutch-German border. This was our first base-station. The weather prospects were still very uncertain at that time. Peter wanted to press on with the plan to go to Kühlungsborn (because of the LiDAR). Carl and I were less certain: southern Europe had the best papers in terms of clear sky prospects at that moment.

Thursday 6 October

Weather predictions now suggested Northern Germany (where Kühlungsborn is situated) could benefit from a zone of clear air created over Denmark and Sleswig-Holstein in northern Germany in the "shadow" of the Norwegian mountains. It was settled that we would try Kühlungsborn. The early part of the day was spent running various errands. More seriously, one of the PC systems operating CAMS had a malfunction and Peter was not able to solve it. We left in the afternoon, driving several hundreds of kilometers to Kühlungsborn, where Michael Gerding of the IAP welcomed us near 22h local time after a long exhausting drive.

Friday October 7

This day, we set up shop in the LiDAR control room of the IAP, which was to become our headquarters for the campaign. An IT specialist of the IAP was brought in to solve the PC trouble - eventually, he managed to find what was wrong and got everything operating again! Meanwhile, we had gotten a sightseeing tour of the IAP facilities. It is a beautiful, modern institute and the guest lodging in town where Michael put us up for the night was very fine. Kühlungsborn itself is a small cozy town, a bathing resort on the Baltic coast in the former Eastern Germany. Peter held a lecture before the institute members, Carl and I made a small beachwalk that afternoon.

click images to enlarge

The LiDAR control room at the IAP became our headquarters. Top: Peter (right) and Carl (left) with the CAMS systems. Bottom: checking the weather predictions and plotting potential locations for our second station (left Peter, middle Carl, right our host Michael)

That evening was a test evening for the LiDAR, to see whether anything needed trouble-shooting. There actually was a problem initially with the LiDAR, but it was solved and didn't hamper the actual observations the next night.

click images to enlarge

the IAP Kühlungsborn LiDAR at work during a test run a day before the actual observing night. Second image shows the beam hitting a low cloud. Photograph by author using an 8mm semi-fisheye.

Seeing the massive laser beam of the LiDAR shooting up into the sky was quite impressive. Meanwhile, the weather was still very dynamic, so we worried about the next night, when all had to happen.

Saturday, October 8th

Based on the latets weather forecasts, we picked a location 91 km to the west for our second site, right in the middle of the projected clear area in the weather forecast. Carl and I would run it, and so we drove away at noon, to the small village of Lebatz (53 deg 58' N, 10 deg 35' E) in Sleswig Holstein, about 30 km north of Lübeck. We had picked a small hotel from the internet there. The hotel owner was a bit surprised by our demand for a room "with a view to the north east". We needed the latter, as the mutual aiming point we had calculated for the Kühlungsborn and Lebatz CAMS systems meant we had to point at 46 degrees elevation to the northeast. Peter at Kühlungsborn filmed 15 degrees north of the Zenith, just north of the LiDAR beams. In that way, we would film the same meteors from both stations, appearing at 95 km altitude over the Baltic sea just north of Kühlungsborn: meteors whose ionization trails next would drift into the LiDAR beams, as a result of a high altitude wind blowing from the north-northeast at 95 km altitude.
Meanwhile, two other Dutch observers, Peter van Leuteren and Sietse Dijkstra, had joined us: they had driven to Lebatz from the eastern Netherlands that same day, arriving about an hour after us.

Just before our car turned into Lebatz (which, by the way, turned out to be one of the rare spots in NW Europe without cellphone coverage), I had noted a small roadsign saying: 'Dunkelsdorf, 1 km'. 'Dunkelsdorf' means "dark village" in German. So naturally, that name appealed to us! After setting up shop in the hotel in Lebatz (our CAMS system would run from the open hotel window, as we needed electric power and a dry place for the PC), we drove the 2 km to Dunkelsdorf, and found a nice hiltop with 360 degrees view. The farmer was working nearby, and gave us permission to use the field that night (he turned out to be an astronomy enthusiast himself).

click image to enlarge

Our observing spot (bottom) near Dunkelsdorf, photographed the morning after

After a good meal in the small tavern at the hotel, Peter v. L. and Sietse left for the observing field at dusk. The sky was clearing at that moment, witha few remnant fields of clouds. This looked very promising for the night! Carl and I stayed at the hotel waiting for the sky to become dark enough to aim and focus the cameras. That took some effort, also because we were not used to this new equipment. But with some trial and error, we managed to get the whole system running: and after the cameras are aimed, and focussed well, the PC takes over and the whole system runs automatically, and we could leave for the field. Neat!

So after setting up, aiming, focussing and initiating the camera systems, Carl and I drove to the observing field as well, arriving there at 20:30 local time. Sietze and Peter v. L. already had seen some bright Draconids, they reported as we arrived. We set up our gear (field bed, sleeping bag, handheld memorecorders, and in my case a tripod with my photo camera) and joined the observations. The last cumulus clouds were moving out of the sky and it became brilliantly clear. Observing due North away from the moon, I determined a limiting magnitude of +6.3 in Draco to my (and my fellow observer's) astonishment, with the milky way visible into Perseus. This was wonderful, I have never experienced such a good sky with moonlight before! Directly in the minutes after I started observing, the first Draconids were seen. So there was activity, at least! Would it lead to a peak near 20h UTC (22h local time)?

Observing the activity peak

It did indeed lead up to a peak just after 22h local time. More and more meteors appeared, shooting away from a radiant in the head of Draco. Around 20 UTC, I counted 3-4 Draconid meteors per minute. Most were rather faint, so we wondered what we would have seen without the moon.... Nevertheless, even in a moonlit sky, the show was impressive, and it was clear the Zenith Hourly Rates must be in the hundreds. We were excited!

We were also worried. Low in the east, below 5 degrees elevation, we could see persistent clouds. That was where our other station was, Kühlungsborn with Peter, Michael and the LiDAR..... Telephonic contact (our cell phone did have coverage from the hilltop) revealed that they had a lot of clouds, but also clear periods.

click diagram to enlarge

ZHR diagram of my observations, suggesting a peak ZHR near 250 just after 20 UTC

My observations suggest that the ZHR at the peak was in the order of 250. This is just an indication, as it are observations with moonlight, from one observer. In total, I observed 248 Draconid meteors in 2.77h effective observing time.

My photo camera with EF 2.0/35mm lens captured 16 Draconids (image above) in slightly less than two hours time: most meteors were simply too faint to be photographed. Our video camera's meanwhile, sensitive to much fainter meteors, filmed hundreds of meteors.

Some meteors left persistent trains. It are these trains of course, that were the target for the LiDAR. Below animated GIF shows a bright Draconid I photographed, with traces of a dissipating persistent trail drifting on the wind in several images obtained after it appeared:

The short movie shows the trail drifting from bottom right to upper left in about 2 minutes time: indeed consistent with a high altitude wind direction from the NE to SW.

After 22h local time (20h UT), activity was on the decline again. The peak was over. Around midnight, we stopped our observations (the CAMS system would run untill 1 am). It was still brilliantly clear: we couldn't have been in a better spot!

click image to enlarge

Four happy observers the morning after the outburst observations. From left to right: Carl Johannink, Peter van Leuteren, Sietse Dijkstra, and the author

Kühlungsborn

The next day, Peter van Leuteren and Sietse drove back to the Netherlands, and Carl and I drove back to Kühlungsborn. Ariving there near 11 am, we heard the story of Peter and Michael. They had a lot of clouds, but luckily also a largely clear period of about an hour around the peak time. This increased our hopes to have filmed at least a few meteors multistation, hopefully with a LiDAR detection as well.

With the data reduced we can now say we filmed at least 34 Draconids plus two sporadic meteors from both stations, yielding accurate atmospheric trajectories, lightcurves, and orbits in the solar system. The LiDAR did have detections as well, but work to correlate these with meteors filmed by us is still in progress. If we do have LiDAR detections that we can correlate with meteors we filmed (more precisely: with the atmospheric trajectories and lightcurves that our multistation filming produced), that will yield a lot of information about processes happening in the upper atmosphere because of these meteors.

Below is a compilation of video meteors filmed by three of the Lebatz cameras and one of the Kühlungsborn cameras. The latter images also shows the LiDAR beams (and clouds, unfortunately). Draconid meteors are moving from top to bottom, everything from another direction is an aircraft, satellite, or sporadic meteor.

It was ten years ago that I last had been involved in such a scientific meteor observing effort - I participated in several of the Leonid meteor outburst scientific campaigns in the 1990-ies. It was exciting to get involved again for the Draconids.

note: I want to warmly thank the people of the IAP and especially Dr Michael Gerding for housing us during the campaign.

Another ROSAT observation

2011-10-15T12:54:00.003+02:00

Yesterday evening was clear, and I again observed the doomed satellite ROSAT (see my previous post), in deep twilight (sun at -6 degrees). It was again bright, magnitude +1, very fast, easy to see even though the sky was still bright blue with only a few stars visible. Like my earlier observation the day before yesterday, it was steady in brightness, with no sign of brightness variations, suggesting it is not tumbling.

Photographically it was a challenge: I had to do some serious image editing tricks to pull the trail out of the bright twilight background on the image below (on the unedited image, the trail is visible but very inconspicuous):

click image to enlarge

These high elevation (near 70 degrees) twilight passes are quickly moving earlier (and too early) in the evening for me: yesterday's was the last one I could expect to realistically observe. Passes at lower elevation (12-14 degrees) in late twilight will become visible for me after tomorrow and might allow me to observe it for a few more days later this week, until these passes move too early as well.

Using Alan Pickup's SatEvo software and the current 10.7cm solar flux, I get a projected decay at October 23. Harro Zimmer, using another model, gets October 24th. These predictions still have an uncertainty of a few days, so expect them to shift over the coming days, amongst others due to changing solar activity.

Observing another doomed satellite: ROSAT

2011-10-13T21:18:00.001+02:00

Shortly after the UARS reentry, which got wide attention, another scientific satellite is about to meet its demise by an uncontrolled plunge into the atmosphere. It is the German X-ray astronomical satellite ROSAT. This satellite is currently predicted to reenter about October 22 to 24.

This evening I watched it pass during twilight (sun at 8 degrees below the horizon, first stars just visible in a blue sky). It was fast, zipping across the sky, and bright: magnitude +1 and an easy naked eye object.

I used the new EF 2.0/35mm lens (a new purchase, first used last weekend during the Draconid meteor outburst, on which I will post in a later post), set to F2.5, making 5 second exposures at 400 ISO. The fast moving objects ran out of the frame of two of the three images. Below is the image thats shows the complete trail. The satellite was moving from left to right, across Cepheus. The streak in top is a streak of cirrus.

click image to enlarge

Back to business - KH-12 USA 129, the STSS demo's and more

2011-10-02T20:53:00.000+02:00

The focus on the UARS decay the past two weeks will not have escaped the frequent readers of this blog. It is now time to leave UARS to rest, and turn back to business as usual .

The past week saw warm and sunny weather. I managed to observe on 27, 28 and 29 September as well as October 1st.

The KH-12 keyhole USA 129 (96-072A) was one of the major targets. Both on the 28th and 29th it flared to mag. +0.5, at 20:17:04.8 (28 Sep) resp. 20:21:04.0 (29 sep) UTC.

On the 29th, the images of USA 129 showed a Breeze-M tank, 04-031C, as a stray:

click image to enlarge

These pieces of Russian space debris pop up more often on my images lately. They are the jettisonable torroidal (doughnut-shaped) fuel tanks of a Breeze-M, the upper stage of a Proton M. There are now over 40 of these spent empty tanks in space, often in highly elliptic orbits representative of a geostationary transfer. Even at considerable distance, they are bright. During perigee passes, they zip through the sky at high speed as bright naked-eye objects. Further out, they move slow but are still relatively bright, as visible on the image above.

The Breeze-M tank above was at a range of over 2700 km (by contrast, USA 129 was at a range of 948 km) at the time of photography, and is a leftover from the 2004 launch of the South American geostationary communication satellite AMAZONAS.

On that same night of September 29th, I used the Samyang 1.4/85mm to target, two of the Space Tracking and Surveillance System (STSS) satellites, STSS Demo 1 and Demo 2. (09-052A & B). Both these faint satellites were captured near their apogee at approximately 1359 km altitude.

click images to enlarge

Other satellites photographed these nights were the Trumpet ELINT and SBIRS low satellites USA 184 (06-027A) and USA 200 (08-010A), two satellites in HEO.

In addition, I used the 61 cm telescope of SSON in California to photograph the enigmatic Prowler again (see also my previous post here for backgrounds on this highly classified satellite).

On September 30th, I was too tired to do serious observations. I however set up the camera with 24 mm lens and automated timer to redo my recent classic startrails circling the celestial pole image, but this time for a total exposure time of 3 hours 20 minutes:

click image to enlarge

Tracking stations along UARS final track - a reconstruction [UPDATED TWICE]

2011-09-28T13:46:00.000+02:00

click map (revised version) to enlarge

Above map provides an overview of groundbased tracking stations in the ESA ESTRACK and the US AFSCN network that are near or on the final trajectory of UARS. For relevant trackings tations, times of Advance of Sight (AOS) or Loss of Sight (LOS) are indicated. UARS is depicted at the point of reentry (see previous post) as indicated by SSC.

From the NASA talk by Johnson, they pinpointed the 04:00 +/- 1 minute UTC time and 14.1 S, 170.2 W location of UARS's demise using detections and non-detections by "a number of sensors".

~~As shown above, the last of these tracking facilties, the ESA station at Awarua, New Zealand, would have detected it and tracked untill it lost sight at 3:56 UTC.~~ ~~Next, there is an 11 minute coverage gap untill it could first have shown up at the Kaena Point tracking facility in Hawaii at 4:07 UTC.~~ [EDIT: it appears that Awarua is a telemetry station only, not a true tracking station. As UARS was a dead satellite not sending telemetry, it then becomes unlikely Awarua played any tracking role: leaving nothing between Kerguelen and Hawaii. Thanks to Dan Fischer for querying me about the character of Awarua station]

As can be seen on the map, none of the regular tracking stations had direct coverage of the reported reentry location, begging the question where the "large number of detections" NASA's Johnson was talking about comes from. UARS could first have shown up at the Kaena Point tracking facility in Hawaii at 4:07 UTC. At that time, it would have been without groundbased tracking for quite some time already (over half an orbit).

Of course, we cannot exclude that a temporary tracking facility (e.g. an AEGIS ship) was employed in Polynesia at the time, providing additional data.

Also, a reader of this blog wrote to me with the suggestion that the US Navy's sensitive network of hydrophones could have picked up a signal when wreckage hit sea surface. I have no idea how feasible that is.

I still feel space-based observations were possibly involved (see my earlier post here), but are not being publicly acknowledged. The early warning satellites DSP F20, DSP F16 and SBIRS Geo-1 would have had coverage of the reentry location.

(note added: if anyone knows of additional tracking stations along the trajectory, info is welcome)

Infrasound?

Note added 29 Sept 2011
Dan Fischer raised the option in the comments that Infrasound detections could be involved. Indeed, this is a possibility (I consulted a Dutch infrasound researcher for an opinion here, and he thinks it is feasible, especially if sonic booms were involved) even though the distances to infrasound arrays involved are large.
A number of infrasound arrays are scattered over the Pacific area, listening for possible atomic detonations in breach of the Nuclear Test Ban treaty. A map of them can be found here. In the wider area, such arrays are located on Tahiti (French Polynesia), Hawaii, the Marquesas and New Caledonia. The UARS reentry location is within this triangular area. Below is a map of infrasound detection arrays located in the Pacific around the published UARS reentry location.

Edit late 29 Sept: Dutch infrasound researcher Läslo Evers just notified me he has checked the Tahiti and New Caledonia infrasound records for the reentry - he finds no sign of it.

click map to enlarge

UARS reentered over Samoa? [slightly updated]

2011-09-28T00:07:00.000+02:00

USSTRATCOM, followed later today by NASA, has released a new reentry time and location estimate for UARS. It puts the time at 04:00 +/- 1 minute UTC and location at 14.1 deg South, 170.2 degrees W. This is over the south-central Pacific, in the vicinity of Samoa.

The time and location is said to be based on a number of detections and non-detections of several "sensors", without clear indication whether these are groundbased or space based sensors (see my previous post here) but I do suspect the latter are involved. The more so since the only ground-based tracking stations in this wide area are on Oahu (Hawaii), Kwajalein and Guam, and none of these would be able to pinpoint this location so exactly as this location is out of their detection range [edit 28 Sep: plus, the final UARS track did not bring it in reach of Guam and Kwajalein anyway]. The description by NASA's Johnson in the video appears deliberately vague to me. [edit 28 Sep: there is of course always the possibility that they happened to have a tracking ship in the vicinity].

I have some lingering concern in the back of my mind about the "neatness" of a reentry at exactly 4:00 UTC (nice and round), but sometimes such coincidences do happen.

Below is a map of the now released reentry point.

click map to enlarge

Could the reentry of UARS have been monitored from Space?

2011-09-26T18:02:00.003+02:00

One of the open questions regarding the inability to pinpoint the exact location and time of the UARS reentry, is whether the US military might have space-based detections from their infra-red early warning satellites.

The US military operates two constellations of such satellites, whose purpose is to detect and provide early warning for enemy ICBM launches using infra-red detection sensors. The older constellation is the DSP (Defense Support Program) series of satellites in geostationary orbit. There is also the newer SBIRS (Space-Based Infrared System) constellation, consisting of one geostationary satellite (SBIRS Geo-1) and two SBIRS sensors piggybacked on HEO satellites (USA 184 and USA 200).

We know that the DSP satellites have, in the past, frequently observed meteoric fireballs. It is therefore widely believed (and indeed likely) that the system should have been able to detect the UARS reentry fireballs as well. The problem is that post-9/11 the DoD has stopped declassifying meteor detections (which were previously shared with meteor scientists). Which makes you wonder whether, if they did detect the UARS reentry fireball, they would be forthcoming with that information. Probably not.

Would the UARS reentry have been visible from one of the DSP or SBIRS satellites? Would they cover the relevant areas? Yes they would.

Below map shows the location (for 4:16 UTC [edit 28 Sep: this was written before the reentry time was revised to 4:00 UTC, see here]) of UARS plus it's track, and the locations of the relevant satellites.

click map to enlarge

Yellow dots are the block 5 DSP satellites, white dots the SBIRS satellites. The green circle outlines show the coverage area of DSP F16, DSP F20, and SBIRS Geo-1.

The DSP's and SBIRS GEO-1 are geostationary and hence always above the geographic spot depicted in the map (with some minor latitudinal variation): for the HEO SBIRS platforms USA 184 and USA 200 the position plotted is for 4:16 UTC.At that time USA 184 was near apogee and basically almost in the same position (in geographic subsatellite point terms) for an hour on each side of 4:16 UTC. USA 200 was moving towards perigee, but would have UARS in view during the whole Africa pass of the latter.

DSP F16, DSP F20, SBIRS GEO-1 over the eastern Pacific as well as the SBIRS platform USA 184 over Siberia would cover the approach track over the Pacific and nominal center of the reentry window of UARS. Basically, they cover UARS on it's final track from New Zealand to over Canada.

Beyond Canada (would UARS have survived well beyond 4:16 UTC), DSP F17 over Brasil and the SBIRS platform USA 200 moving over Africa would have taken over, joined by DSP F18 plus DSP F21 and DSP F22 (all over Africa or the Indian Ocean) once over Africa.

I also checked whether the experimental satellites in the STSS (Space Tracking and Surveillance System) series would have been able to capture it: turns out they would not have, as these satellites (in low earth orbits) were not near the relevant part of the UARS track at that time.

In conclusion: there is plenty of possibilities for the US military to have detected the UARS reentry from space, using their space-based assets (DSP and SBIRS) in GEO and HEO. Even if groundbased tracking facilities were sparse over UARS' final track, the space-based sensors should have been able to observe and pinpoint the reentry.

Yet, I suspect that if these observations exist (allowing the DoD a clear indication as to where UARS debris might have showered down), this information will not be released to the public.

(text slightly editted 27 Sep to clarify USA 200 movement)

"UARS crash" at Okotoks Alberta (Canada) now confirmed to be hoax

2011-09-25T14:26:00.003+02:00

After all the hectic of the previous night, I spent yesterday out of house in the dunes and near the beach. Time to pick up now where I left.

NASA has held a teleconference. Basically, they did not report anything new regarding the potential reentry location than what I already reported here based on SSC and Harro Zimmer's conclusions. Note that this NASA map released is basically the same I posted here earlier.

I don't share some of the critique currently levelled at NASA. See discussion at the end of this post.

Okotoks, Canada: a HOAX
The Okotoks (Alberta, Canada) video and report of debris being found (see earlier post here) - news media now report it is a HOAX. Seems I was right with having my reservations. [update 26 sep: more here. The report on wreckage was a hoax created by an aspiring film maker, apparently]

Aircraft contrails being mistaken for UARS

Meanwhile, simple aircraft contrails keep being mistaken for UARS as well: see the previous post and another case here.

Radar artefacts being mistaken for UARS

This one that is doing the rounds, is a mis-interpretation of a very common weather radar artefact. Note how the streak neatly points to the radar origin in the center.

Chinese lantern balloons being presented as "UARS"

As I pointed out in the previous post, footage of Chinese lantern balloons are either deliberately or mistakenly being passed off as "UARS" in the media as well.

Possible confusion with meteoric fireballs

To complicate the picture, there is also the point that "normal" meteoric fireballs appear and can be mistaken for UARS. Multiple such fireballs occur somewhere on this world every day.

Indeed, we had a very nice meteoric firebal (seen by amongst others myself while waiting for the UARS pass) of mag. -5 appear 5 minutes before the 1:37 UTC UARS pass on the 24th. Klaas Jobse has a nice all-sky image of that one here. Yet another one appeared a mere 17 minutes later (video of both fireballs here, again by Klaas Jobse). These were meteoric fireballs, little bits of asteroid or comet debris not related to UARS at all.

While it didn't fool experienced observers like me, laypersons could have easily mistaken it for UARS debris.

Some genuine reports of bright fireball phenomena seen around the predicted reentry time from a.o. Canada, could be such cases of meteoric fireballs. Without clear details on duration and character, it is difficult to discern between these and any potential real reentry observations.

Critique on NASA: I don't share that critique

There is currently a lot of critique on NASA that they can't pinpoint the point of reentry. I think those critiques are unfounded and stem from unrealistic expectations.

All I can say is: people expect too much of NASA and modern technology, notably under the influence of unrealistic TV-series that depict NASA as know-it-alls that can do anything (with just a few computer keystrokes and maybe a hack into a satellite feed here and there typically, according to the TV series that increasingly mold the public's "reality").

But even the best technology and best experts have their limits (and in terms of the actual tracking, this technology is not operated by NASA, but by the US Air Force, by the way), and with the last few UARS revolutions largely over empty ocean devoid of tracking stations, things simply get difficult. There are limits to what models can do when devoid of real-time tracking sensor input.

I might, given time and energy, elaborate on that later in a separate post

False "UARS" video's

2011-09-24T21:03:00.001+02:00

Some video's are doing the rounds, some in respected news media, purporting to be showing the demise of UARS but in reality definitely something else.

This one posted on Space.com is an example. This clearly shows a Chinese lantern balloon, not UARS: you can see the bag and burner.

Another one is here (with thanks to Dan Fischer for pointing me to it): this British video on the website of The Telegraph simply shows an aircraft with contrail. As science writer Dan Fischer remarked in despair about this one on twitter: "don't you people ever watch the sky?!". Indeed, one would expect people recognize aircraft and contrails these days. Yet we see them pop up time and again in the media, as purported footage of "fireballs" and now as "UARS".

There is more of this stuff doing the rounds on the intarwebz currently. So be very careful with purported footage and images of "UARS reentering". A lot is not what it seems.

UARS update 24 Sept (2) - so where did it crash?!?

2011-09-24T12:31:00.003+02:00

It is still not entirely clear where and when UARS met a fiery end. SSC issued a bulletin stating 4:16 +/- 53 minutes UTC. Harro Zimmer issued a final prediction of 4:15 +/- 9 minutes UTC.

The latter would place the reentry over an area defined by the Northeast Pacific and northern Canada.

click map to enlarge

The problem is that the reentry was (according to a lack of reliable reports so far) not unambiguously observed, and probably that the last revolutions took UARS over areas (oceans and central Africa) where tracking stations are sparse. Perhaps the DoD might have space-based observations from their Infrared early warning satellites, but the question is whether those data will become public or not.

Okotoks video - UARS or not?

Meanwhile, a video from Okotoks, Alberta, Canada, hit the internet, purporting to show fireballs from the UARS reentry. However, to many people including me the video does not look right.

We feel it looks more like a series of "Chinese lanterns", small toy hot air balloons. The individual "fragments" just don't show enough evolution over the video, they are too steady, amongst others (also, in the video the guy shooting it says it is "September 22nd", a wrong date).

I could be wrong though, and the general geographic area is in line with the predictions. So while I don't want to write off the video completely, I do keep my reservations about it.

UPDATE 11:25 UTC: there is now an UNCONFIRMED report of debris pieces having been found near where the video was taken. No details, no pictures, so could be bogus or mistake, no way to say.

UARS update, 24 Sept (1)

2011-09-24T04:15:00.000+02:00

UARS reentry update, 24 Sept 02:00 UTC
click here to check for more recent updates

We are now probably less than 3 hours from UARS reentry.

Using SatEvo software and the latest few orbital updates, re-entry is projected for 24 Sept 4:20-5:05 UTC: in essence, 4:45 UT +/- half an hour. [next sentence corrected] This would indicate Africa and possibly Australia as places which might get to see it.[/corrected]

Watched the 01:37 UTC pass here: this UARS pass was with the satellite completely in earth shadow. Nothing was seen, which means it is not glowing yet.

To make up for missing the decay (this was the last realisticly visible UARS pass for me in the Netherlands), I was treated on a beautiful meteoric fireball at 01:32:44 UTC, at least magnitude -5 if not brighter, appearing due south. It moved through Cetus ending some 10-15 degrees above the horizon. Mediumfast, and with a wake.

This is probably my last pre-reentry UARS update: I am very tired (it is 4:15 am here), the show is over as far as the Netherlands is concerned, so I am going to bed and will see tomorrow morning where UARS came down.

click image to enlarge

UARS reentry update, 23 Sept (5)

2011-09-23T23:25:00.001+02:00

UARS reentry update, 23 Sept 21:20 UTC
click here to check for more recent updates

SatEvo software with the latest orbital elements projects the re-entry at nominally 5:25 UTC (24th), so the time is slightly moving away again from 6+ UTC towards an earlier time.

Harro Zimmer predicts, using a more sophisticated model, 4:15 UTC +/- 90 minutes.

I covered the 21:05 UTC pass here, maximum altitude 57 degrees. It was a pass completely is shadow, so UARS would only be visible if it was already developing plasma phenomena. I did not see it (using both camera, and visually wityh 10 x 50 binoculars) so it isn't glowing yet.

click diagram to enlarge

UARS reentry update 23 Sept (4)

2011-09-23T20:38:00.002+02:00

UARS reentry update, 23 Sept 18:30 UTC
click here to check for more recent updates

SatEvo software with the latest orbital elements now suggests re-entry at about 5-6 UTC (24th).

Harro Zimmer, using a much more sophisticated model, suggests 3:45 UTC, +/- 90 minutes.

click diagram to enlarge

UARS reentry update 23 Sept (3)

2011-09-23T15:34:00.002+02:00

UARS reentry update, 23 Sept 13:30 UTC
click here to check for more recent updates

The nominal projected times for the UARS decay are moving forward again, to later times (which is less favourable for Europe). The latest three orbits at the moment of writing suggest times between 2 UT and 3:45 UT on the 24th.

click diagram to enlarge

UARS reentry update Sep 23 (2)

2011-09-23T10:51:00.001+02:00

UARS reentry update, 23 Sept 8:45 UTC
click here to check for more recent updates

New orbital update, time shifted forward by 2 hours again. Shows that the uncertainty is still many hours. Nominal time now 24 Sep 02:00 UTC, but moving somewhat towards the right direction (for me in the Netherlands) . Here's hoping it will eventually move to near 23 Sep 21 UT.....

click diagram to enlarge

UARS reentry update 23 Sept (1)

2011-09-23T09:50:00.001+02:00

UARS reentry update, 23 Sept 7:45 UTC
click here to check for more recent updates

The projected time of decay is still shifting considerabely with each orbit update: over the past 10 hours, it has hifted back and forth by several hours. The last few orbital updates tend to shift the projected reentry to a later time, early on the 24th, bringing a decay near the USA in view again

At the moment of writing, the nominal projected reentry time using SatEvo and current solar flux data is 4:15 UTC on the 24th. This still has an uncertainty of a couple of hours, though.

Below diagram depicts how the projected renetry time has fluctuated with each new orbit released over the past two days:

click diagram to enlarge

2011-09-22T23:55:00.001+02:00

The following UARS related NOTAM was posted by the FAA:

!FDC 1/2095 FDC .. SPECIAL NOTICE .. EFFECTIVE IMMEDIATELY UNTIL 1109252359 UTC. AIRCRAFT ARE ADVISED THAT A POTENTIAL HAZARD MAY OCCUR DUE TO REENTRY OF SATELLITE UARS INTO THE EARTH'S ATMOSPHERE. FURTHER NOTAMS WILL BE ISSUED IF SPECIFIC INFORMATION BECOMES AVAILABLE. IN THE INTEREST OF FLIGHT SAFETY, IT IS CRITICAL THAT ALL PILOTS/FLIGHT CREW MEMBERS REPORT ANY OBSERVED FALLING SPACE DEBRIS TO THE APPROPRIATE ATC FACILITY AND INCLUDE POSITION, ALTITUDE, TIME, AND DIRECTION OF DEBRIS OBSERVED. THE DOMESTIC EVENTS NETWORK /DEN/ TELEPHONE 202-493-5107, IS THE FAA COORDINATION FACILITY.

UARS update, September 22 pm

2011-09-22T22:43:00.001+02:00

UARS update 22 September 20:30 UTC

The projected decay time for UARS keeps shifting back and forth with each orbital update. Over the course of today, it has oscilated between 19:00 UT on the 23rd to 01:00 UT on the 24th.

The last few orbits tend to favour the later part of this time window, but it could as easily swing back to the earlier part of the window again over the course of tonight and tomorrow.

This just goes to show that the uncertainties are still large and still amount to many hours. Over the course of tomorrow, it will become gradually more clear. The current time window is however exciting, as we have passes visible from Europe including the Netherlands during that time span, notably around 21h UT.

click diagram to enlarge

UARS update, Sept 22 am

2011-09-22T11:00:00.000+02:00

UARS update 22 Sept 08:45 UTC

Re-entry of UARS is now projected on the 23rd. Latest orbit plus current solar flux and Alan Pickup's fine SatEvo software suggest a nominal time near 19:00 UTC on the 23rd, but at this time that still has an uncertainty of several hours (I suggest up to at least 6 hours).

Areas with the best chances to see the reentry are currently for a swat that includes South-America, Europe, Russia, central Asia, southeast Asia and Australia, which all have passes in the hours around the nominal predicted time. It is increasingly unlikely that the USA will get to see anything of it.

UARS update, September 21 pm

2011-09-21T22:16:00.002+02:00

UARS update, 21 Sept, 20:00 UTC

Based on the latest orbital elements from Space-Track, the projected reentry time is slowly moving earlier. The nominal value is now late September 23 (nominal 20:30 UTC, but with still many, many hours uncertainty). But within uncertainties, early September 24 (in UTC terms) is certainly not yet out of the picture. A lot can still happen in the two days left, e.g. changes in solar activity.

Below is an updated diagram of the observed and predicted orbital evolution in terms of apogee and perigee altitudes.

click diagram to enlarge

Eternal circling of the sky - and a METOP-A flare

2011-09-21T13:40:00.000+02:00

As I pointed out in my previous post, the evening of 19 September was reasonably clear (the odd streak of clouds every now and then).

After I observed USA 129 (and incidentally Topex flashing nicely, see previous post), I set up the camera with the automated wire release for a long series of images on the celestial pole, using the EF 2.8/24mm wide angle lens.

click image to enlarge

Result is above "classic" star trail image, showing the eternal circling of the sky around the celestial pole. It was constructed by stacking 165 images of 15 seconds each, shot over a time interval of 44 minutes. Note that the Polestar makes a small circle segment too - it is not exactly at the celestial pole.

The long crossing lines are aircraft (I am close to a major airport). The near-vertical trail in the upper left corner is a satellite flare however: the European weather satellite METOP-A (06-044A).

Below is a detail from the single image that showed the METOP-A flare (at about 20:37:55 UTC, 19 September). Very faintly, the double trail of a NOSS duo, NOSS 3-2 (03-054 A & C) can be seen as well. As this part of the image is close to the image edge, it suffers a bit from coma with this wide angle lens.

click image to enlarge

In the old days of analogue photography, a 44 minute star trail image like this would not have been possible from my urban locality: the image would have fogged too much. Modern digital and especially image stacking techniques, make it possible.

Topex/Poseidon flaring

2011-09-21T13:00:00.001+02:00

Monday evening was clear. I targetted the KH-12 Keyhole USA 129 - it is expected to manoeuvre one of these days.

While watching it (and photographing it), a bright mag. +0.5 flash occurred close to it, followed by another one and than a longer +1.5 flare. It turned out to be the malfunctioned US-French Oceanographic satellite Topex/Poseidon (92-052A), which I have observed flashing before. It malfunctioned in 2006 and since has started to tumble.

Below is the image showing both USA 129 and Topex/Poseidon, the latter showing the three flares:

click image to enlarge

The image yields this brightness curve, with peaks (two narrow and one broad) spaced 3.6 seconds apart:

click diagram to enlarge

UARS update 21 Sept am

2011-09-21T11:02:00.000+02:00

Note: forecast and diagram now superceded by update here.

All eyes of the satellite world are now firmly on UARS. Unfortunately, I have no visible passes here these last few days of its existence.

The predictions for the moment of re-entry keep fluctuating between late September 23 and early September 24. Using Alan Pickup's SatEvo software and a 10.7 cm solar flux value of 145 plus this morning's latest elset, the nominal prediction is for the early hours of September 24 but this time still has an uncertainty of up to half a day.

Below diagram shows the changes in apogee altitudes (blue) and perigee altitudes (red) of UARS over September, plus a forecast of the future evolution of them (grey) untill re-entry.

click diagram to enlarge

USA 129 with a Chinese rocket, and a failed attempt for a last view of UARS

2011-09-19T17:08:00.000+02:00

Yesterday afternoon it cleared fantastically. In the evening, I targetted the KH-12 Keyhole USA 129 (96-072A), which I also observed on the 11th and 14th under much more challenging conditions.

USA 129 had some confusion in store: at the moment it appeared from behind the roof on its ascending trajectory, not one but two bright objects appeared, side by side and moving more or less parallel.

click image to enlarge

One of the objects (the westernmost one) moved slightly faster than the other. It was a Chinese Long March rocket booster, CZ-2C r/b (09-061B) used to launch the SJ-11-01 experimental satellite.

USA 129 itself next slowly flared to mag. +0.5 at about 19:35:05 UTC.

The first image showed, besides USA 129 and CZ-2C r/b, yet a third, very faint trail. It didn't match any known object. After some enhancing and looking at it in detail, I think it is actually a meteor, not a satellite. As my attention was to the bright and unexpected USA 129/CZ-2C r/b chance duo, I did not see the object visually.

In the early morning, UARS, now only days from re-entry, would make a pass emerging from earth shadow at 20 degrees altitude under Orion near 3:50 UTC (5:50 am local time). This was probably my last chance to see it before re-entry.

When I woke up and checked the sky it was clear apart from a field of clouds in the northwest. Grabbing my gear, patches of clouds unfortunately moved in south as well. Short story: patch of clouds right under Orion right at the moment UARS would pass....so UARS not seen, alas.

The expected decay of UARS is moving more and more forward in time, and is now set for the second half of September 23rd.

UARS re-entry Update (and Nanosail-D, and IGS 1B)

2011-09-16T15:05:00.002+02:00

UARS update: It seems that the re-entry moment for UARS, the defunct NASA Upper Atmosphere Research Satellite, is moving forward in time, as Harro Zimmer pointed out on the Seesat-L list.

NASA and SSC Space-Track both settle for a decay on or near 24 September, and so do independant analysis by Harro Zimmer as well as my own assessment (using Alan Pickup's SatEvo software with current 10.7cm flux values).

As the orbital development near decay is highly influenced by solar activity, there currently is an uncertainty of possibly up to a few days in these predictions. Yet it seems save to say that UARS has not much more than a week left.

Nanosail-D update: Meanwhile, that other NASA object up there slowly coming down, NASA's experimental solar sail Nanosail-D, seems not quite willing to give up. It's current orbit and current values for 10.7cm solar flux suggest it will hang on at least another month, untill late October. Same caveats as for UARS apply.

IGS 1B update: this defunct Japanese spy satellite which is steadily coming down (see earlier post here and earlier posts linked their in) since it malfunctioned in 2007, likewise seems intend on spending some more time up there. The current orbit plus solar activity now give a nominal re-entry prognosis for early 2013 instead of 2012. This date is certainly still going to shift back or forth considerably however, depending on how solar activity develops.

Wednesday's fireball over the US southwest was not UARS

2011-09-15T17:31:00.002+02:00

A brilliant fireball was seen and filmed over the US southwest (Arizona, Nevada and California) last night. Some media suggest it could be connected to UARS, the US satellite about to plunge down in the atmosphere later this month.

It was definitely not UARS though. Not only was UARS still being tracked and hence in orbit after the fireball appeared (approx. 19:45 MST on the 14th, or 2:45 UTC on the 15th): but it was simply not passing over that part of the USA at that time. It was hence not UARS, or a piece of UARS.

USA 161 new orbit finally established

2011-09-14T16:48:00.000+02:00

The saga earlier covered here and here is finally coming to an end: it seems that the KH-12 keyhole USA 161 now no longer is escaping our detection.

The reboost on August 24 has provided our observer's and analysts corps with quite a challenge. After initial failures to recover it, the satellite was detected by several observers (including me) for a number of times in the early days of September. But in each case it was subsequently lost again and each new preliminary orbit solution put forward seemed to be wrong (see the two posts linked above in the introduction). Analysts were in despair, and observers confused.

Then Ted finally found a solution which seemed to agree with all observations and asked observers to search according to this search orbit early this week. Following this, Scott Tilley in the USA indeed recovered the object in a position much as predicted by Ted's solution, with Russell Eberst in Scotland following suit.

The now established orbit is quite different from the earlier search orbits. Instead of the perigee having been raised, it turns out that it has been lowered, with the perigee 40 km lower and apogee 120 km lowered.

Watch UARS - it's dropping!

2011-09-10T00:25:00.003+02:00

Several news outlets are abuzz (e.g. here and here) about UARS, the defunct Upper Atmosphere Research Satellite, which is in the last days of its life.

click image to enlarge

Launched on Space Shuttle STS-48 in 1991, it was shut down in 2005 and it's orbit lowered to speed up decay.

That moment of decay is now near, with the 6 tonnes satellite expected to re-enter into our atmosphere in the last days of September or first days of October. At this moment , it is not possible to predict the moment of decay more exactly than this, and hence it is impossible to say where (over which part of the world) the re-entry will take place. At the moment of writing, the satellite already has come down to a 244 x 275 km orbit. The nominal decay date is currently projected to be around September 28-29 but has an uncertainty of several days.

UARS is that big, that parts of it might actually survive re-entry and impact on land or sea. Modelling by NASA suggests up to 532 kg of material, broken up into tens of pieces, might survive re-entry, with the biggest piece being perhaps in the order of just over 150 kg. The odds of this debris hitting someone are small however.

UARS is a large satellite that can be quite bright and easily seen by the naked eye: in the past, I have seen it attain brightnesses up to mag. +0.5, as bright as the brightest stars in the sky.

The image above shows UARS photographed by me on 16 June 2010 from Leiden, the Netherlands, when it showed a small flare.

Twitter

2011-09-07T19:31:00.000+02:00

I am giving Twitter a try - I know, I am late to jump on this bandwagon, but what with this observing blog and Facebook and all, it is already enough thin gs to update. Anyway, click on the small blue button with twitter logo in the top of the sidebar if you are interested in my tweets. They will not all be about satellites though, and some might occasionally be in Dutch.

SBSS 1

2011-09-07T16:01:00.000+02:00

The attention to the hunt for USA 161 means I have a backlog of other objects to report. One of these is my first observation of SBSS 1 (2010-048A), the first object in the Space Based Space Surveillance (SBSS) series.

click image to enlarge

The picture above was made in the evening of September 1st, using the new Samyang 1.4/85mm lens. It shows SBSS 1 moving (left to right) through the northern part of Cygnus (bright star at left is Deneb).

SBSS 1 is the pathfinder mission in the SBSS series and was launched a year ago on 25 September 2010. It is too faint for my 2.5/50mm lens, but the 1.4/85mm Samyang captures it well and has a FOV that is wide enough to show the full trail.

The satellite consists of a 30cm telescope with a 2.4 megapixel sensor. It's purpose is to track other objects in space. A picture of it during assembly can be seen here.

Above: mission and launch patches from the SBSS 1 launch

USA 161 playing hide-and-seek with observers

2011-09-07T15:29:00.000+02:00

A few days ago, I wrote about the effort to recover the KH-12 Keyhole optical reconnaissance satellite USA 161 (01-044A). After it went "missing" following August 24, and not everybody bought into the opinion that it was de-orbitted, it was recovered in the first days of September by an effort of several observers, including Pierre Neirinck and me. It had made a massive orbital manoeuvre (for more details, read here).

Following Pierre Neirinck's and my positive observation on September 1-2 already reported earlier, Björn Gimmle in Norway as well as Pierre and I failed to see it on the night of September 2-3. This could (in the case of Pierre and me) however have been due to unfavourable observing conditions at both our localities in France and the Netherlands.

Next Russell Eberst in Scotland observed it again on September 3-4. However, on subsequent orbits it definitely got lost again. Scott Tilley in the US could not find it on September 5 and neither could Pierre Neirinck in France (I had meanwhile dropped out of the chase due to bad weather).

Next, Scott Tilley positively observed it on September 6th in an orbital position definitely out of sync with Pierre and my observations from September 1-2. This indicated that USA 161 made yet another major manoeuvre around the time of Russell's September 3-4 observation.

The situation now had gotten very confusing, with one of the analysts trying to solve the discrepancies by suggesting that Russell's observation was not USA 161 but a random stray. This is unlikely though, as any object in LEO big enough to be mistaken for USA 161 is catalogued, and Russell's object did not match any of these known catalogued objects. Moreover, as another analyst remarked, the solution to exclude Russell's observation and link our September 2-3 observations with Scott's September 6 observation, would yield very unrealistic drag parameters.

It got even more confusing for a short while, when Italian observer Alberto Rango reported a possible observation on 6-7 September, but with hesitation as he wasn't too sure. In this case, it quickly turned out to be a stray, ironically the French optical reconnaissance satellite Spot 2.

So, for the moment we have lost USA 161 again. Our observer's corps is now trying to search according to a number of possible orbital solutions, most of them no more than educated guesses. I am confident that given time, it will be found again. Given that the weather has turned bad and that the advancing winter is quickly diminishing my midnight window for USA 161 (it can now only be seen low in the north, where I have horizon obstruction), I think I am out of the chase however.

SPECTACULAR flare by IGS 1B!

2011-09-02T23:29:00.009+02:00

Click images to enlarge! Do!

This picture speaks for itself. When this happened, I was jumping up and down in excitement, shouting "WOHOOOOO!!!!".

The picture shows the malfunctioned Japanese spy satellite IGS 1B flaring to at least magnitude -8 in Hercules (M13 can be seen as a fuzzy "star" in the picture) at 20:58:40 UTC (2 Sept 2011). It rivalled the best of Iridium flares.

Image shot with the Canon EOS 450D + EF 2.5/50mm Macro, 800 ISO. It was somewhat hazy with a few contrails in the sky, one of them lighting up around the flare for added drama.

Needless to say, I was extremely happy that this happened while the camera was open...

USA 161: "The reports of my death are greatly exaggerated..."

2011-09-02T13:09:00.012+02:00

KH-12 Keyhole USA 161 (01-044A) is alive! Pierre Neirinck and I observed it last night around 23:55 UTC (1 Sept). Below is one of the two images of it which I captured:

click image to enlarge

The Keyhole, launched from Vandenbergh on 5 October 2001, went AWOL on or short after 24 August, with several observers failing to observe it in a window well around its last orbital position after that date. This lead to some suggestions, covered earlier here, that it could have been de-orbitted. After all, a new Keyhole, USA 224 (11-002A) had been launched in the same orbital plane on January 20, 2011, ostensibly as a replacement for USA 161.

Not everybody took to the idea of a de-orbit for USA 161 though. It's much older sister ship in the evening plane, USA 129 (96-072A), was after all still active even though USA 186 (05-042A) had been placed in the same orbital plane in 2005. So why de-orbit the newer USA 161 but leave the much older (and presumably less modern) USA 129 up?

The alternative to a de-orbit, was a massive reboost into a different orbit. This option got more credibility when an anonymous radio observer reported the possible reception of a radiosignal from USA 161 on August 26. Based on this possible reception, Ted Molczan dispatched a number of search orbits to the active observers, and the hunt for ~~Red October~~ USA 161 was on...

Skies were overcast in Leiden at that time, but on 28-29 August it cleared somewhat (with the emphasis on "somewhat"). I tried to cover the nominal plane of the search orbits that night (which meant staying up late to 2 am local time) under conditions that can only be described as abominable (thin and sometimes thicker clouds) but failed to recover the satellite. That could easily have been due to the conditions though. In France, Pierre Neirinck suffered the same conditions.

On the night of 30-31 August, Pierre Neirinck in France spotted an object that could be USA 161 near 00:17 UTC. As his sky suffered from clouds, there was some uncertainty in the position he obtained. His observation suggested that the satellite was moving in an orbital plane that was shifted slightly more eastwards than the plane of the search orbits.

On the night of August 31-September 1, Björn Gimmle in Norway possibly observed it again near 23:20 UTC, but he wasn't too sure. Pierre Neirinck observing from France between 22:58-23:23 UTC did not see it. Neither did I, keeping (under good sky conditions) a visual and photographic watch between 23:31-23:46 UTC. ~~Red October~~ USA 161 turned out to be elusive and not willing to give up it's location easily!

Third time is a charm however (or, as we say in Dutch: Drie maal is Scheepsrecht, which is ambiguous to translate beacuse the exact meaning of "scheepsrecht" is under dispute: but it is something like "Three times is Ship's Justice" or "Three times is Alderman's Justice").

On the night of September 1-2, both Pierre in France and I in the Netherlands observed it unequivocally around 23:55 UTC. Keeping a visual and photographic watch under good conditions, I picked it up visually somewhat east of Polaris and under Cassiopeia, and just under the FOV of my camera. I quickly re-aimed and shot two images (one of them shown above), yielding four points. It was steady and at its brightest about mag. +2, a naked eye object. At the same time, Pierre in France also saw it visually and got three points.

With these data of last night, the new orbit is starting to get a bit of shape - probably enough for others to recover it more easily the coming nights. Probably not here at Leiden though: the sky has grown very hazy today (thin clouds) and I need some sleep.

The very preliminary orbit still needs more observations before it becomes accurate, but it looks like the perigee has been significantly raised to twice the altitude it was (from 303 km to ~590 km), and apogee slightly lowered (from 911 km to ~780 km).

These kind of situations, where a satellite makes a big manoeuvre and the hunt is on to recover it, are always exciting times where the hobby gets most fun!

Rush hour on the Sagitta-Vulpecula border

2011-08-31T15:27:00.006+02:00

Yesterday, while preparing the series of images on comet 2009 P1 Garrad (see previous post), I captured below 10 second exposure using the Samyang 1.4/85 mm lens. The telescope mount was not yet adequately following that time.

It shows satellite rush hour on the Sagitta-Vulpecula border: as much as four objects in this single image measuring less than 10 degrees!

11-037B is related to the SPEKTR R (Radioastron) launch. Kosmos 530 (72-087C) is clearly slowly flashing.

click image to enlarge

Later that evening, I captured the FIA Radar 1 (10-046A) passing through Cygnus amidst whisps of clouds, making for this eerie picture (made using the Canon EF 2.5/50mm Macro):

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OT: comet 2009 P1 Garradd with the new 1.4/85 mm lens (updated)

2011-08-31T11:19:00.004+02:00

Yesterday evening (30 Aug 2011) started reasonably clear, so I set up the small Meade ETX-70, put the Canon EOS 450D with the new Samyang 1.4/85 mm lens piggyback on it, and made a series of images of the Sagitta-Vulpecula border area, where comet 2009 P1 Garradd is currently located.

Sky conditions were variable. Out of 97 images (of 10 seconds exposure each), I selected the 34 best for the stack below. The comet (small, but with a clear tail) is in the center, parts of Sagitta with M71 are at left, the "coathanger" cluster is at right:

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A detail of the image at full pixel resolution:

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NOSS 2-1 (C) very bright

2011-08-30T23:30:00.007+02:00

In the evening of August 28, during a short clearing, I was testing a new lens, the very fine Samyang F1.4/85 mm Aspherical IF.

The EOS 450D with the lens was mounted piggyback on my Meade ETX-70, with the ETX following the movement of the stars.

While making a series of images of the Deneb area, situated near the zenith, a bright naked eye satellite of mag. +1.5 passed through Cygnus and the camera field.

On the image, it turned out to be accompanied by two other satellites, much fainter. It actually was the NOSS 2-1 trio, and the bright one was the (C) component (1990-050C). Below is the image:

click image to enlarge

NOSS-es usually do not get this bright in the zenith and I have never seen 1990-050C this bright before. Scott Tilley from the USA has recently observed the same unusual brightness of NOSS 2-1(C), and so did Brad Young.

The lens I was testing, the Samyang F1.4/85 mm Aspherical IF which gets raving reviews on the internet, turns out to be an extremely fine F1.4 lens. The optical quality is astounding, and this at a cost of only €269,- !

KH-12 USA 161 de-orbited? [updated 02/09/2011]

2011-08-26T10:58:00.012+02:00

UPDATE 2 Sept 2011: USA 161 is Still Alive! It has not been deorbitted but made a large manoeuvre. Read more about the recovery here.

Negative observations on Wednesday and Thursday 24-25 and 25-26 August reported by Russell Eberst from Scotland on SeeSat-L and Pierre Neirinck from France (priv. com) suggest that the KH-12 Keyhole USA 161 (2001-044A), an advanced high resolution optical reconnaisance satellite launched on 5 October 2001, has either undergone a large manoeuvre or (more likely) has been de-orbited last week.

Earlier this year (January 20, 2011), USA 224 (2011-002A) was launched as NROL-49 and put in the same orbital plane as USA 161, probably as a replacement for the latter.

Below are two archive pictures I shot of USA 161 brightly flaring twice on 30 July 2009:

click image to enlarge

The remaining KH-12 constellation (if indeed USA 161 has been de-orbitted last week) now consists of three satellites: USA 129 (96-072A), USA 186 (05-042A) and USA 224 (2011-002A), the oldest of which (USA 129) is now 15 years in service.

USA 224 which replaced USA 161 represents the noon and midnight plane. USA 129 and USA 186 represent the morning and evening plane. Below diagram shows the satellite constellation as it is now USA 161 has presumably been de-orbitted:

click diagram to enlarge

Progress M-11M, and a spectacular flare by IGS 1B

2011-08-23T23:30:00.007+02:00

At 9:35 UTC on 23rd August 2011, the Progress M-11M spacecraft (2011-027A) which had been attached to the International Space Station (ISS) since June was decoupled from the latter. It will orbit earth on its own for 9 days and will do various measurements, before being de-orbited to burn up over the Pacific.

On the evening of the 23rd near 20:29 UTC (22:29 local time) I watched them both during a fine near-zenith pass. The Progress spacecraft was about 1 minute ahead of the ISS in time, and attained a maximum brightness of mag. +0.5. Below two images show the Progress (top image) and the ISS a minute later(bottom image), both in Lyra:

click images to enlarge

Next I observed the IGS 5 rocket (09-066B), and IGS 1B (a malfunctioned Japanese spy satellite that is up for an uncontrolled re-entry in 2012-2013, see here). Both objects flared.

The IGS 5 rocket stage flared to mag. -0.5 at about 20:35:55 UTC. But IGS 1B (03-009B) flared much more spectacularly, to at least mag. -3 at 20:43:01 UTC, while passing through the zenith! An image of this splendid flare (captured close to the edge of the image) is the top image below, while the bottom image shows it while ascending in the south, just west of Altair:

click images to enlarge

Satellites far and near

2011-08-21T17:58:00.005+02:00

Both Friday and Saturday evening were very clear, and the moon not yet a nuisance untill midnight.

On Friday I targetted both a few LEO and HEO objects. The KH-12 Keyhole USA 129 (96-072A), the SAR Lacrosse 3 (97-064A) and the FIA Radar 1 (10-046A) were observed, although a misalignment of the camera in the case of FIA R1 resulted in only one point on the latter. As I was waiting for FIA R1 to pass, the International Space Station (ISS) made a majestic, very bright zenith pass.

Next I changed the EF 2.5/50mm lens for the Carl Zeiss Jena Sonnar MC 2.8/180mm, and targetted two faint and distant HEO objects, The Trumpet ELINT and SBIRS platform USA 200 (08-010A) and the SDS 3-4 data communications satellite USA 179 (04-034A). Two images of both are shown below.

click images to enlarge

While sleeping, the G68 Sierra Stars Observatory Telescope in California made images for me that resulted in a position on the enigmatic Prowler (90-097E).

Saturday evening was clear as well. This time, I only targetted LEO objects: the Japanese malfunctioned satellite IGS 1B (03-009B), and both the KH-12 USA 129 and the FIA Radar 1 again.

As I was observing, a group of people attending a birthday party of one of the neighbours came onto the courtyard for a smoke. Curious, they asked me what I was doing, and after a short explanation from my part, the group of six watched in an excited state when IGS 1B made a very bright pass. It was easily visible naked eye, and they all saw it.

Below is one of the images from this evening: the FIA Radar 1 (10-046A) passing through Lyra (brightest star is Vega).

click image to enlarge

Nanosail-D: a pattern in the Chaos

2011-08-18T15:34:00.004+02:00

Earlier I reported on my August 14 observations of the experimental Solar sail Nanosail-D (2010-062L), including a brightness variation diagram derived from one of the images.

Initially, I could not see any clear pattern in it, so I called it "irregular". Next, Alain Figer from France pointed out it was not so irregular after all. His own images from August 16th (URL's here) show a very neat pattern of one major flash, then two secondary flashes, then a major flash again. On his images, the major flashes are 0.73 seconds apart.

Going back to my observations, it turns out it is indeed possible to find a similar periodicity of 0.73 +/- 0.03 seconds. The secondary flashes appear to be 0.73/3 = ~0.24 from these main peaks: in other words, main and secondary peaks fit a ~0.24s pattern.

Below diagram shows it. the lowest line gives the observed peaks, with the red triangles representing the main 0.73s cycle. The yellow tringles point out several secondary maxima at ~0.24s after the main cycle peak; the grey/white triangles point at a hint of a similar pattern ~0.24s before he main cycle peaks.
The upper line shows the modelled behaviour: a main peak (black triangle) each 0.73s, with secondary and tertiary peaks at ~0.24s intervals.

click diagram to enlarge

Nanosail-D flashing rapidly and brightly

2011-08-15T16:57:00.005+02:00

As in late May and early June, Nanosail-D (2010-062L), the experimental NASA Solar Sail is making favourable passes again and under favourable conditions becomes bright and is flashing rapidly.

Yesterday evening around 22:50 local time (20:50 UTC) I observed it when it made a near-zenith pass, from SW to NE. While ascending and going through the zenith it was quite bright and an easy naked-eye object, reaching mag. +1.5. It was rapidly and very irregularly, rather nervously flashing.

I shot four images, two of which are shown below: in the first image, the brightness variation is photographically less apparent than it was visually, because the trail is near saturation. It shows the Solar sail passing just below Lyra (Vega in top left) along with a stray, the French Optical Remote Sensing satellite Spot 4 (98-017A, the fainter of the two trails).

The second image, shot while Nanosail-D was getting fainter, shows the sharp flashes more readily.

click images to enlarge

From the latter image, I could derive this brightness variation diagram:

click diagram to enlarge

A large number of sharp brightness peaks can be seen: I count some 26 peaks in a 10.05 seconds time span, the one more prominent than the other. No regularity in the pattern is apparent.

Perseid

2011-08-10T19:25:00.004+02:00

Yesterday evening saw very dynamic weather conditions, with the sky going from overcast to cklear to overcast in a matter of minutes. I managed to photograph the FIA Radar 1 (10-046A) and IGS 1B (03-009B).

Then I set up my camera with an Aputure automatic timer and let it take 20 second pictures all night. I did this earlier, to construct a time-lapse showing sky rotation. This time, it was also meant to capture some early Perseid meteors.

I captured one (below), low in the west.

click image to enlarge

Some of my pictures on Wired.com

2011-07-15T13:55:00.003+02:00

Wired.com has published a short photographic item about secret spacecraft today.

Two of the images in it were shot by me: a photograph of Lacrosse 3 and one of Mentor 4.

Prowler

2011-07-12T17:25:00.001+02:00

Among the family of classified satellites, three stand out as more mystifying than the rest: Misty 1 & 2, PAN, and Prowler.

The latter has long existed in the realm of rumours only. It was launched by Space Shuttle Atlantis on mission STS-38, which was a classified DoD mission launched on 15 November 1990. Officialy only one satellite, USA 67, was launched from the Atlantis payload bay. This is believed to be a geostationary SDS communications satellite, SDS 2-2.

STS-38 mission patch

USSTRATCOM released catalogue numbers (but no public orbit) for three objects connected to this launch: the SDS satellite USA 67 itself (90-097B, 20963) plus two rocket bodies (90-097 C & D, 20964 and 20965).

The latter was puzzling, as it is one too many (see the discussion by Ted Molcan here), This was the start of the idea that a second, unacknowledged object was launched by STS-38 as well.

In 2004 an NBC journalist referred to such a secret payload by the name of Prowler, in a news-item discussing a Senate debate about a classified spy satellite program drawing criticism for massive cost overruns. The same journalist, citing anonymous sources, did so again in 2007.

According to these stories, Prowler was an experimental satellite used for close inspection of other (non-US) satellites in geostationary orbit (see discussion here), reportedly coming to within decimeters of some satellites. There are suggestions that it was a test of technology which, in wartime, could be used to sabotage enemies' space assets. It was also said to employ stealth technologies to evade easy detection.

Meanwhile, US amateur observers Ed Cannon and Mike McCants had discovered an unidentified near-geostationary object in July 1998. As time progressed and more and more ISON and amateur-discovered objects could be identified with specific launches, this one was one of few left unidentified. This in turn led to suggestions that the object in question was the rumoured unacknowledged STS-38 launch, Prowler. It was likely discovered only after its active lifetime ended, and it was put in a disposal orbit (see below).

Since then, a long term analysis by Ted Molczan has strengthened this identification. The object has al the right characteristics in terms of brightness behaviour and orbital behaviour. It currently is in an unusual librating disposal orbit that seems devised to keep it out of reach of Soviet tracking facilities (see discussion in depth by Ted here). In a second analysis, Ted showed that STS-38 indeed had the opportunity to launch this object and some tell-tale clues to that are present in the manoeuvering history of STS-38 Atlantis. The whole history of the object, from launch onwards but also including the final disposal orbit when the stealth character of the object was lost, was designed with low detectability by Soviet tracking facilities in mind (see Ted's discussion here).

The object now resides in a currently 13-degrees inclined orbit librating between 73 W and 136 W, putting it over the eastern Pacific, with visibility from the western United States. Over the past two weeks , I imaged it a number of times, using the 0.61-meter "remote" telescope of Sierra Stars observatory in California. Below is one of the better images, shot on the morning of July 6th:

click image to enlarge

An update on IGS-1B

2011-07-06T15:09:00.008+02:00

Along the line of expectations, our tracking data show that the Japanese spy satellite IGS 1B (2003-009B) which malfunctioned in March 2007, keeps coming down (see earlier coverage here and here).

Early July 2011, the perigee had come down to 450 km and the Mean Motion (the number of orbital revolutions per day) is steadfastily increasing as the orbit becames more narrow:

The predicted decay date keeps shifting back and forth, being highly dependant on solar activity. Solar activity has been back to modest the past two months. As a result, the decay date forecast has shifted further away in time.

If solar activity does not increase, forecasted decay will be in late 2013 (SatEvo with current solar flux F10.7 cm = 85, elset 11184.15154535). If it does increase - which is likely, as we are on the approach to a solar maximum - it will be earlier, possibly as early as mid-2012.

Meanwhile, it is interesting to see how the still active sister-ship IGS 1A (2003-009A), launched in the same 2003 launch, is faring. Above diagram shows the evolution of the orbital inclination. IGS 1B's orbital inclination is clearly drifting, consistent with loss of control. IGS 1A's orbital inclination initially was allowed to co-drift with IGS 1B, but then altered in a manoeuvre mid-2008 that brought the inclination up again, to match the other IGS-es in the constellation. As of 2010, it is kept more or less steady, librating around a value of 97.39 degrees, the sun-synchronous value for a 487 x 498 km orbit.

PAN, and the NOSS 3-5 duo

2011-07-06T12:07:00.005+02:00

Monday evening was a nice clear evening with a very transparent sky.

I observed the NOSS 3-5 duo (11-014 A & B), which was captured in a very fine image with a stray nearby, the rocket from the Kosmos 1697 launch (85-097B). De double parallel trail above is the NOSS duo, the single trail under an angle is the Russian rocket (bright star near trails is Deneb):

click image to enlarge

I also took opportunity of the transparent sky to target some geostationary objects low in the southeast. Targets were PAN (09-047A) and Mentor 4 (09-001A):

click image to enlarge

Imaging geostationary satellites using a remote telescope [UPDATED]

2011-07-04T18:00:00.004+02:00

I have been using the "remote" telescopes of Sierra Stars observatory in California and Winer Observatory in Nevada for some time now to image asteroids (recently, earthgrazing NEA 2011 MD).

The past two days I have used the Sierra Stars Obs. 0.61-meter Cassegrain telescope to make some "remote" images of classified geostationary satellites that are not visible from the Netherlands, but visible from the western United States. It concerned the recently launched SBIRS-GEO1 satellite (11-019A) and the mysterious object (90-097E) that is most likely Prowler , launched in 1990 on STS-38.

Below are the images: as this is a guided telescope, the satellites have created trails on the images. Top image: Prowler. Bottom image: SBIRS-GEO1, plus an unidentified object (UPDATE: the latter object might be the SBIRS-GEO r/b).

click images to enlarge

OT: more imagery of the earthgrazing asteroid 2011 MD

2011-06-28T16:45:00.003+02:00

Like yesterday, I used the 0.61-meter F/10 Cassegrain of Sierra Stars Observatory (G68) in California again to image the earthgrazing asteroid 2011 MD, this time a few hours after closest approach.

Below animated GIF was made from three 30 second exposures, spaced 30 seconds, starting at 09:35:01 UTC (28 June).

OT: Close Encounters of a Rocky Kind (2011 MD)

2011-06-27T16:54:00.008+02:00

Today, a small asteroid, 2011 MD, made a very close pass by the earth, coming to within a distance of 12,400 km at about 13:30 UTC (June 27). That is well within the distance of geostationary satellites, and even within the distance of GPS satellites in MEO!

This morning, some 5 hours before closest approach, I used the 0.61-meter F/10 Cassegrain of Sierra Stars Observatory (G68) in California, to capture this PHA earthgrazer.

click image to enlarge

This image is a 30 second CCD exposure taken between 08:32:00 and 08:32:30 UTC (June 27, 2011). In these 30 seconds, the fast moving object left a notable bright trail on the image. Star field is in Serpens, image center approximately RA 15h35m57s, dec. +19.441 degrees.

UPDATE: more of my 2011 MD imagery shot on the 28th here.

NanoSail-D: a brief note on how I construct these brightness curves

2011-06-06T16:24:00.006+02:00

Some people have asked me how I get the brightness curves from my images. So here is a brief explanation.

On each image, the satellite has made a trail. Start and end times of the exposure are well known, and the start and end of the trail corresponds to these times.

Next it is as simple as using software (e.g. MaximDL, or IRIS) that can read pixel values along a line: let the software read a line that corresponds to the satellite trail on the image! With MaximDL or IRIS, this is as simple as drawing a line over the screen with your mouse, exactly over the satellite trail. The software then reads the pixel values along this line. The resulting data can be exported as a data table.

These data are then read into a spreadsheet I created, that for each data point interpolates the corresponding time (remember that the time of the first and last datapoint in the dataset is known: start and end of the exposure).

Now, this assumes the movement of the satellite on the image is linear. Strictly speaking, the apparent speed of the satellite is not linear. However, with short exposures (10s) that will not be a really big source of error.

NanoSail-D: evolution of the flash pattern during a pass

2011-06-05T22:16:00.008+02:00

Yesterday evening at 23:00 CEST I observed a twilight pass of the experimental NASA solar sail NanoSail-D again (see earlier and later observations here).

This pass allowed me to capture a series of brightness curves, which document the evolution of the flash pattern during a single pass, as the looking angle is changing (looking "edge on" aroudn culmination, and then more and more "on the tail"as it is descending) . The change in flash pattern is profound: this is clearly a very complex matter where the flash pattern highly depends on the relative position of the object to the observer.

click images to enlarge

It starts (image and diagram 1) with a lot of irregular flashes, spaced 0.3 - 0.9s apart (average 0.49s but with large standard deviation).

Next (image and diagram 2), a nice semi-regular sinusoid pattern develops, flashes spaced 1.24 - 1.45 s (average 1.33s)

Then (image and diagrams 3 and 4), the period increases, the pattern transforming to a slower sinusoid with peaks first 5.61s apart, then somewhat decreasing again to 4.11s apart (edit: or maybe not: the firts "peak"might be a sub-peak. The valleys seem at similar distance to the previous diagram). Superimposed on this, a shorter cycle of minor subvariation can be suspected, with various periods.

This slower variation in the last two diagrams is why Bram, me and some other observers got the impression, on this and some past passes, of the period almost "disappearing" when NanoSail-D was descending on altitudes of ~35 degrees.

Two of the trail images in a bit more detail: note the difference in flash pattern:

click images to enlarge

NanoSail-D Galore

2011-06-04T11:05:00.007+02:00

Yesterday evening, I observed a twilight pass (sun at -7 degrees altitude and a still bright blue sky) of NanoSail-D, the NASA experimental solar sail (see earlier posts here). It passed at 44 degrees in the east, and after culmination became very bright again, flashing to mag. 0.

Because of the bright twilight sky I had to tone down the ISO to 400 and diaphragm to F4.0. The images show the flashing behaviour very neatly, and I obtained two spectacular sinusoid brigthness curves (the second one is from the image shown):

click images to enlarge

The flash period is definitely slightly variable, varying between 1.2 and 1.5 seconds with an average of 1.35 +/- 0.12 seconds.

With the current orbit, decay is projected for mid-August.

note added: click the 'Nanosail-D' label below to see later posts on NanoSail.

Yet more bright NanoSail-D, and an unidentified object from the same launch

2011-06-03T00:59:00.005+02:00

Yesterday evening (Wednesday evening) was very clear and saw another fine pass of NanoSail-D (10-062L), the experiental NASA solar sail. As on previous occasions, it became very bright after culmination, while descending to the southern horizon: reaching an easy naked eye magnitude of +0.5. It is still flashing, but trail saturation on the images meant I could not get a reliable brightness variation curve this time. Below are two images: one that shows it just north of the Coma Berenices star cluster, the other shows it passing south of Bootes into Virgo somewhat later (bright star in the top is Arcturus):

click images to enlarge

Tonight (Tuesday evening) I had another pass, a low west pass at 35 degrees altitude this time. And....it was invisible, to the naked eye at least.

On April 27th, Russell Eberst observed an unidentified object that moves in the same orbital plane as NanoSail-D and appears to be "something" from the same launch (see also here). It was subsequently observed by a number of other observers (and perhaps earlier, on March 3, by Greg Roberts), and yesterday I photographed it:

click image to enlarge

Another object observed this evening was Lacrosse 5 (05-016A).

More flashing NanoSail-D, and flaring KH-12 USA 224

2011-06-01T21:00:00.008+02:00

A week after my May 24 observations, I observed NanoSail-D (2010-062L) again, the experimental NASA solar sail.

NanoSail-D (image: NASA/MSFC)

As a week ago, it became very bright after culmination, while descending in the south, and was rapidly flashing again. It was easily seen by the naked eye, reaching mag. +1 or possibly +0.5.

In fact it is so bright, that the pixel brightness of the trail reached saturation on two of the three images. The first image (below) did yield brightness information: the resulting curve is shown beneath it. The flash period is irregular, but periods of 0.5s and 1.0s pop up frequently in the diagram (for actual determined flash times, see here. Astrometry on the satellite itself can be found here).

click images to enlarge

As can be seen on the images, the satellite was in a race with an untimely field of clouds (the orangish streaks in the images), staying just ahead of it. Visually, the brightness fluctuation was much more apparent than it is on these images (due to the saturation of the latter): it was very clearly flashing.

Nanosail-D was not the only object flashing. USA 224 (11-002A), the new KH-12 Keyhole launched on January 20 this year, flared too, while passing through the zenith, with flares at 23:48:27.3 and 23:48:31.8 UTC (May 31). The "saddle" and elevated brightness between the two flares is interesting (the trail is notably fainter before the first flash, and subsequent images show it is fainter again after the second flash):

click images to enlarge

This was the second time I imaged USA 224 (The first time was May 24). In addition to USA 224 and NanoSail, I also imaged another KH-12 Keyhole, USA 161 (01-044A), and a Lacrosse SAR, Lacrosse 3 (97-064A).

Nanosail-D: a spectacular show of bright flashes!

2011-05-25T12:46:00.005+02:00

Last night I finally was able to capture Nanosail-D (10-062L), the NASA experimental solar sail. It put on a spectacular show, flashing rapidly, becoming an easy naked-eye object after culmination when it reached magnitude +1.

As it gradually brightened from invisibility to naked-eye brightness while passing at 61 degrees altitude due east, it initially flared rapidly, in an irregular pattern, at a rate of 1 to 3 flashes per second. below is the first image, and two other where the trail runs out of the image frame (in haste, I aimed badly when repositioning the camera):

click images to enlarge

When it descended towards the South-Southeast, it became brighter, reaching mag. +1. The flashing pattern became somewhat more regular and slowed down to about one flash per 1.6 seconds. On the image, the trail is quite saturated and hence the brightness variability on the image below is less apparent than it was visually. Visually, the objet was clearly "winking", very cool to see:

click images to enlarge

PAN at its new slot at 45.0 E

2011-05-12T15:58:00.000+02:00

Below is an image I shot in the evening of May 9, under not too good conditions (moonlight, and some twilight left).

It shows PAN (09-047A) in its new position at 45.0 E, following the relocation from 49.0 E early May.

Image was shot using the Carl Zeiss Jena Sonnar MC 2.8/180 mm.

click image to enlarge

ISS over the Sun

2011-05-10T18:36:00.002+02:00

Late this afternoon (10 May 2011), at 17:29:25 CEST (15:29:25 UTC), the International Space Station (ISS) passed in front of the Sun disc again as seen from the SatTrackCam station, silhoueting the Space Station on the solar disc.

Like on March 24th, I used my small ETX-70 telescope equiped with a Solar Screen Filter, to photograph the event. This time I used prime focus plus a Kenko 2x converter, instead of eyepiece-projection, effectively yielding a f=700mm F/10 system.

Four images out of the series show the ISS silhouted againts the sun, along with several sunspots. Below is a composite image of the four images (showing the ISS four times), plus a detail. The ISS solar arrays are well visible.

click images to enlarge

UNID-I 3 May 2011 = PAN [UPDATED]

2011-05-09T17:18:00.011+02:00

On May 3rd, I found two unidentified geostationary objects close to Galaxy 27 and Intelsat 12 (see report and pictures here).

One, UNID-I, was stable in brightness. The other, UNID-II, was flashing. I imaged UNID-I the next night (May 4th) as well, showing it drifting westwards. I might have imaged UNID-II again too, though misidentifying it at that time as Intelsat 12 (except for the occasionally very bright UNID-II, the objects were, due to worse observing conditions, at the edge of detectability).

At that time (see the link above) there already was some suspicion that UNID-I could be the enigmatic classified geostationary satellite PAN (09-047A), caught in the act of yet another relocation.

That suspicion is now confirmed, following additional imaging by Peter Wakelin from the UK on May 8th. Still drifting when I picked it up on May 3rd, PAN now appears to have settled in a new position at 44.9 E, just west of Galaxy 27 and Intelsat 12. It has moved 2 degrees higher in my local sky, to an altitude of 19 degrees.

The identity of the second, flashing UNID, UNID-II which is still drifting westwards on May 8th, is still uncertain. While it is possibly the Indian communication satellite GSat-2 (03-018A) in the act of relocating, Space-Track still lists that object stable in its usual orbit slot placing it at 48 E. So we have something of a remaining mystery to solve there (although in the end, it will probably turn out to be Gsat-2, with Space-Track for some reason failing yet to recognize it is being moved).

UPDATE 09/05/2011: about an hour after I posted this, Space-Track updated the orbit for Gsat-2, showing that UNID-II is indeed Gsat-2, probably on it's way to the graveyard orbit. So, it appears I beat Space-Track to it by several days!

PAN (09-047A) has a history of frequent relocations, making this already enigmatic satellite the more enigmatic. Previous to this early May 2011 relocation, it relocated in early December 2010, an event that I was the first person to detect as well. So far, it has been located at 33.0 E from late 2009 to May 2010 and then was moved to 38.0 E; then to 49.0 E in December 2010; and now to 44.9 E in May 2011.

[UPDATED] Two Unidentified Geostationary Objects on May 3 and 4

2011-05-05T15:30:00.007+02:00

May 3 was an unusually clear evening, and I decided to target a few classified geostationary satellites, using the Carl Zeiss Jena Sonnar MC 2.8/180mm.

While imaging the region of PAN (09-047A) and Mentor 4 (09-001A), I found two unidentified objects. Yes: two.

The first object, UNID-I, was discovered close to the commercial geosats Galaxy 27 (99-052A) and Intelsat 12 (00-068A). It was present on multiple images, and the astrometry shows it is stable in declination. It was about as bright as the two commercial geosats, and stable in brightness.

The plot thickened, when a second unidentified object, UNID-II, was discovered just east of the first, just north of the commercial geostationary Syracuse 3A (05-041B). This object was irregular in brightness, alternating between faint and very bright (comparable to Mentor 4 at peak brightness, i.e. about mag. +8).

Below image shows UNID-I near Galaxy 27 and Intelsat 12:

click image to enlarge

The two images below show UNID-II near Syracuse 3A, and the clear flaring behaviour of the UNID.

click image to enlarge

On May 4th, the sky quality was poorer. Nevertheless I tried to recover the two objects, with partial success: UNID-II was captured again on several images.

It had drifted westwards, closer to Galaxy 27 and Intelsat 12 towards the position of UNID-I. The latter was not visible on the images, most likely due to the poor sky quality (Galaxy 27 and Intelsat 12 were barely visible either).

The object showed a clear variable brightness behaviour, being invisible in one image and very bright in the next one taken 30s later. Together with the slowly changing declination, this shows that the object is likely UNID-II, not UNID-I.

Below images were taken 30 seconds apart: the object is bright in one, and invisible in the other:

click image to enlarge

In the series of images, it is present in the following images:

from - to (UTC, May 4th)
---------------------------------------
21:03:02.30 - 21:03:12.35
21:04:02.30 - 21:04:12.35 - very bright
21:05:02.30 - 21:05:12.35
21:07:32.30 - 21:07:42.35
21:08:02.30 - 21:08:12.35
21:08:32.30 - 21:08:42.35 - very bright
21:11:02.30 - 21:11:12.35
21:12:02.30 - 21:12:12.35
21:13:02.30 - 21:13:12.35 - very bright
21:14:02.30 - 21:14:12.35 - very bright
---------------------------------------

As can be seen, there is a clear semi-1 minute periodicity in this.

I have no idea as to the true identity of these two objects. As I could find no trace of PAN (09-047A) near Yamal 202 on my May 3rd images, it is possible that UNID-I is PAN once again relocating.

The presence of a second, tumbling/spinning object, UNID-II, close to it however suggests that more is going on. Finding two UNID's close together is definitely weird and might suggest a connection between the two objects.

UNID-II has a small but clear inclination to it's orbit and appears to be drifting westwards. UNID-I is stable in declination, indicating an inclination close to zero. It might be drifting as well (only more observations will tell, given that I failed to find it on May 4th).

UPDATE 5-5-2011:
Ted Molczan feels UNID-II (the flashing one) could be the Indian commercial geosat Gsat 2 (03-018A) in the act of relocating. UNID-I could indeed well be, as I suggested in my report on Satobs, the classified geosat PAN (09-047A) relocating, according to Mike McCants. I captured the same satellite relocating in December last year: this enigmatic satellite is frequently on the move.

More on the IGS 1B fuel tank, and the (reduced) risk of it re-entering

2011-04-24T18:24:00.007+02:00

At the end of the previous weekend, I posted an extensive post on the malfunctioned Japanese spy satellite IGS 1B (03-009B). It malfuntioned in 2007, has subsequently lost orbital altitude, and is now expected to re-enter early 2012.

The concerns was, that it might have a still partly filled fuel tank - potentially creating a risk at re-entry, a concern similar to that for the re-entry of USA 193 in 2008 (which, for that reason, was destroyed on-orbit by a SM-3 missile). This greatly worried me, the more as no news on this was appearing from either the Japanese, or US Space Command (who no doubt must have been aware that IGS 1B was coming down - an object like this will certainly be tracked).

My assessment of a potentially still half-full tank, was, as I indicated, at best an "educated guess". Noted amateur observer Ted Molczan from Toronto has now made an independant assessment of the situation, notably on the absolute amount of fuel left. Below I quote from his analysis, in which he writes (after first noting that he gets similar results to mine as to the probable time of decay, i.e early 2012):

"I agree that IGS 1B could decay from orbit in 2012, with perhaps half of its initial fuel mass; however, I believe that its initial fuel mass probably was far less than that of USA 193 - between approximately 28 kg and nearly 100 kg, compared with the 450 kg of USA 193. If half of IGS 1B's fuel has been expended, then between 14 kg and 50 kg may remain - at most 10 percent of USA 193's fuel load. Only the Government of Japan knows for certain the quantity of fuel that remains, but if my estimate is in the ballpark, then the risk of an uncontrolled decay from orbit would be much less than for USA 193."

[...]

"USA 193 carried about 450 kg of fuel, none of which had been expended by the time of its impending decay, due to its failure soon after it reached orbit. I believe that IGS 1B may have considerably less fuel for the following reasons:

1. IGS 1B was designed to operate at a considerably higher altitude than USA 193 (485 km vs. 360 km), which means that it was subject to far less atmospheric drag, which would have decreased the quantity of fuel required for orbit maintenance.

2. IGS 1B's total mass is reportedly about half that of USA 193 (1200 kg vs. 2300 kg). For a given velocity change, the fuel expenditure varies in direct proportion to total spacecraft mass.

3. IGS 1B died four years into what was reportedly a five year mission, so might already have expended most of its fuel."  

[note from Marco Langbroek: but its sister ship IGS 1A is still maintaining orbit 8 years later, as I indicated in my original post, suggesting that these satellites carry more fuel than for a minimum 5 year mission]

"With respect to points #1 and #2, assuming that IGS 1B's ballistic coefficient (mass divided by cross-sectional area) is similar to that of USA 193, and that its fuel supply was designed to enable operating up to twice the reported 5 year design life, i.e. 10 years, then the total velocity change required to maintain 485 km altitude would have been about 53 m/s (metres per second). Assuming IGS 1B uses the same fuel as USA 193, then for its mass of 1200 kg, the required initial fuel mass would have been just 28 kg - far less than that of USA 193.

Factoring in point #3: assuming provision of fuel for 10 years operation, then IGS 1B might have consumed 40 percent of its fuel by the time it died, four years after launch. Considering that its first couple of years of operation coincided with the tail end of the  previous solar maximum, its fuel use could have been somewhat greater; assuming for the sake of argument that half its fuel has been expended, then 14 kg would remain.

I based this rough estimate on data found in the respected textbook/reference Space Mission Analysis and Design III, specifically the annual velocity change required to maintain low Earth orbits against decay, depending on altitude, ballistic coefficient and solar activity. I assumed that fuel for attitude control was negligible, and that IGS 1B was not designed to be de-orbited at the end of its useful life (the latter would have increased the initial fuel mass to nearly 100 kg, with perhaps 50 kg remaining after four years of operation, still far less than USA 193 carried.)"

I have high trust in Ted's assessment: and the result is somewhat of a reassurrance: 14 to 50 kg of fuel is an order of a magnitude less than the 450 kg of fuel of USA 193. While no uncontrolled re-entry is without danger, these figures from Ted's assessment lead me to think that IGS 1B is clearly less of a threath than USA 193 was.

Ted's assessement is exactly the kind of thing I called for in my earlier post, when I wrote:

Instead of watching this one quietly go down, I would prefer to see a good risk assessment done [...] a clear argument presented as to why it would not be a danger in this case, given all the fuzz created around falling fuel tanks with USA 193.

Ideally, this should of course have come from the Japanese themselves (which refused to say anything pertinent to one of the reporters that contected me over this, besides the simple statement that there was "no risk"). In absence of that, Ted's assessment is a good thing to have.

Yet another Japanese satellite failure!

2011-04-23T16:52:00.004+02:00

The Japanese, already suffering from the major devastation of the recent earthquake, truely don't seem to catch a break.

Today news broke that yet another Japanese radar- and optical satellite has broken down on orbit. It concerns ALOS, a non-classified Earth Observation satellite including radar, visual and infrared sensing equipment.

This comes after the 2007 malfunction of the classified SAR satellite IGS 1B, which is now developing into a re-entry hazard concern for 2012 (as discussed extensively on this blog in a post from last weekend): and the 2010 malfunction of their other classified SAR satellite, IGS R2.

In the aftermath of the recent earthquake, losing their prized remote sensing satellites must really be a pain for the Japanese: this is all really at the most untimely of moments.

Unlike IGS 1B, ALOS is not a direct re-entry hazard for the near future. In a 697 x 694 km orbit (notably higher than that of the IGS-es), it will take a considerable time for it to decay.

KH-12 USA 129 flaring: and IGS 1B again

2011-04-22T11:41:00.005+02:00

A period of sunny weather commenced the past week, albeit with a trend towards increasing hazyness. I observed on the 19th, 20th and 21st of April, targets being the evening KH-12's USA 129 (96-072A) and USA 186 (05-042A), as well as IGS 1B (03-009B). An attempt to locate the geostationary satellite Mentor 2 (98-029A) on the 20th failed, probably because of the poor observing conditions.

Yesterday evening (21st April) the sky was quite hazy with, during twilight, abundant whisps of thin clouds. USA 129 (96-072A) slowly flared to mag. 0 at about 19:56:15 UTC, and the resulting picture of the flare amidst thin clouds in a still bluish twilight sky, looks very eerie:

click image to enlarge

Some what later, I made this shot of IGS 1B (03-009B) gracefully sailing through Bootes:

click image to enlarge

My story about the re-entry of the above pictured malfunctioned IGS 1B satellite in about a year from now, has been picked up, notably after Jim Oberg reposted it on the NASA Spaceflight Forum here. Two journalists contacted me with questions, and my post itself attracted some US Government attention (when the Executive Office of the President visits your weblog, you know it is being taken serious). So I guess some people have woken up now, and hopefully we will soon see a serious risk assessment and more pertinent information by the Japanese as to the tank content of the satellite.

NROL-34 recovered!

2011-04-19T12:13:00.017+02:00

NROL-34 code-named ODIN is a classified payload launched by the NRO on 15 April 2011 (last Friday), 04:24:10 UTC. The launch itself was called FRIGGA, see the launch and mission patches here.

Initially suspected to be a Trumpet destined for a Molniya orbit by independant analysts, a change of mind was promoted short before the launch by new information that suggested it to be a new NOSS pair. NOSS stands for Naval Ocean Surveillance System, and the newer NOSS typically consist of two satellites forming a close tandem.

After the launch of NROL-34 on April 15, the hunt was on to recover it: and hence for me it was very frustrating to see that a period of cloudy skies ensued at Cospar 4353!

Initial attempts by several observers to locate it according to orbit estimates published by Ted failed (see here and here). Then Mike reported an observation of what could be the NOSS duo from Texas on April 17, prompting a new orbit estimate. However, several other observers plus Mike himself next failed to recover it according to this orbit estimate (see here, here, here and here). So, the situation was very unclear: where was NROL-34, and what did Mike see?

Independant of each other, BWGS president Bram Dorreman in Belgium and me in Leiden, the Netherlands, turned back to Ted's initial orbit estimate, for a prolonged orbit plane search, yesterday evening: Bram visually, and I used the camera. This was the first clear evening allowing this. Conditions were poor, as the only potentially visible pass was very low in the west (20 degrees altitude), with a very poor phase angle and hence expected low brightness. I therefore decided to use the EF 2.8/100 mm Macro lens, as this picks up fainter objects - the trade-off is however a smaller FOV. I started the photographic survey at 20:05:20 UTC, making a continuous series of 10s exposures separated by 10 seconds each, and ended at 20:13:00 UTC.

On the 4th exposure (20:06:22.30 - 20:06:32.35 UTC), a very faint trail showed up. The trail is extremely marginal in quality, barely visible above the background noise: but it turned out to be one of the two NOSS objects (the leading one, probably) of the elusive NROL-34!

Below is (a part of) the image, with the very faint, barely visible trail marked by arrows at the start and end (you might have to adjust your monitor settings to see it, and definitely need to click the image below to full size):

click image to enlarge

After measuring the image, and finding no match to a known object, I privately mailed to Ted and Mike (and inadvertently switched the trail ends in that proces, initially reporting the trail end as the first position and the trail start as the second, instead of the correct other way around: a revised, correct report can be found here). The object passed about 4 minutes earlier than the nominal predicted pass time from Ted's initial NROL-34 elset estimate.

Meanwhile, it turned out, Bram in Belgium had visually (binoculars) picked up the same object, as well as a second object trailing it by 16 seconds. The latter probably was too faint to be photographed, as it was not visible on my images.

Based on a quick revised search orbit from Bram and my observations, Ted next picked it up a few hours later from Toronto in Canada, and Kevin Fetter observed it from the USA as well, as did Tim Luton.

So, three days after launch NROL-34 finally has been recovered. The game can now begin to further refine the orbit, and monitor any subsequent manoeuvres. The new NOSS has been given the provisional designation NOSS 3-5 by our group of amateur observers.

Later that evening, I observed IGS 1B (03-009B: see my post on the expected re-entry of this object a year from now here) and the KH-12 USA 186 (05-042A), as well as (as strays) a duo of Globalstars, Globalstar 4 (98-008D) and Globalstar 37 (99-012D), trying to impersonate a NOSS (as if the evening wasn't already confusing enough!).