Sunday 24 April 2011

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

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.

Saturday 23 April 2011

Yet another Japanese satellite failure!

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.

Friday 22 April 2011

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

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.

Tuesday 19 April 2011

NROL-34 recovered!

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!).

Saturday 16 April 2011

[UPDATED] Another Malfunctioned Spy Satellite is Coming Down - with Hydrazine onboard

UPDATE (24 Apr 2011): in a separate post, I discuss a new analysis by Ted Molczan, who has done an independent assessment on the absolute amount of fuel left in the tank of IGS 1B. This assessment, in which I have a large degree of trust, suggests that the absolute amount of fuel carried by IGS 1B is substantially lower than was the case with USA 193. This is somewhat of a reassurance. Read more about it in the separate post here.

Summary - this long post discusses the imminent uncontrolled re-entry of the malfunctioned Japanese spy satellite IGS 1B (2003-009B) in the first half of next year (2012): and points out that there might be a potentially hazardous half-full tank of fuel still in the defunct satellite, mimicking the situation with USA 193 in 2008.

Prologue - Three years ago: USA 193 and 'Operation Burnt Frost'

Three years ago, a malfunctioned US Spy Satellite called USA 193 (2006-057A) made headlines, when it was destroyed by a modified SM-3 missile fired from the USS Lake Erie near Hawaii. This was done in order to avoid a potentially dangerous uncontrolled re-entry early 2008 (see my coverage of the story here). According to US Government officials, the tank with toxic Hydrazine fuel onboard the satellite was the main reason for this unusual and spectacular pre-emptive destruction code-named "Operation Burnt Frost", although a few independant analysts (e.g. Yousaf Butt) maintain that the real motives were instead to prevent cutting edge technology from falling in the wrong hands, and perhaps also to provide a symbol warning to the Chinese. The Chinese had conducted a succesfull anti-satellite test (ASAT) a year earlier which greatly worried the USA. The suggestion that it was not the potential hydrazine hazard but another motive that prompted the decision to destroy USA 193, was hotly debated, notably by noted Space journalist Jim Oberg who strongly defended the official position (for more examples of the heated discussion, see here).

2012: IGS 1B, Another Spy Satellite Coming Down

Now, three years later, another malfunctioned spy satellite is coming down. And like USA 193, it likely too has a significant reserve of fuel left in it's onboard tank.

Image below: the doomed malfunctioned satellite IGS 1B, a bright naked-eye object, photographed by the author from Leiden (the Netherlands) on 21 April 2011

click image to enlarge

The satellite in question is a Japanese spy satellite, IGS 1B (2003-009B), believed to weigh 1.2 tons (about one-third of the weight of USA 193). It was launched on a H-2A rocket on 28 March 2003 together with a sister satellite, IGS 1A (2003-009A). IGS stands for Intelligence Gathering Satellite, an English translation of the Japanese designation joho shushu eisei.

Both satellites, placed in similar ~488 km, 97.3 degree inclined Polar orbits, were meant to work in tandem, the IGS-A object being an optical imaging reconnaissance satellite, the IGS-B object a Synthetic Aperture Radar (SAR) reconnaissance satellite with imaging resolutions believed to be in the order of 1 meter. Their mission -and that of subsequent similar IGS satellites launched- probably was and is primarily to keep an eye on North Korea's Ballistic Missile program, as well as providing an imaging aid in case of natural disasters occuring in Japan.

In order to carry out their mission, these satellites carefully maintain a very stable sun-synchronous orbit by means of frequent small manoeuvres. While some sources (including the CIA) list an intended life-span of 5 years, the optical satellite of the pair (IGS 1A) appears to be still actively maintaining its orbit as of April 2011, over 8 years after launch of the pair, indicating that these satellites probably have a significant amount of fuel onboard to enable these orbit maintenance manoeuvres.

Both objects in question are classified, meaning that neither the Japanese government nor the US Government make orbital elements available. Amateur trackers, including this author, have however kept track of both objects since their launch, determining and updating their orbits (periodically published here).

March 2007: Loss of power, and loss of altitude, by IGS 1B

In the spring of 2007, the Japanese government made public that the radar satellite of the pair, IGS 1B, experienced a serious malfunction involving loss of power on or near March 25, 2007.

Indeed, amateur tracking data show that since March 2007 the satellite has stopped the careful maintainance of its orbit and instead has started to lose altitude. In addition, amateur trackers (including this author) started to report an irregular brightness behaviour of the satellite, including some spectacular flares not seen prior to 2007 (e.g. reports here, here, here, here, here and here), indicating a loss of attitude control.

The following diagram, created by this author based on published orbital updates calculated by Mike McCants from amateur tracking data (including data by this author) shows how the Mean Motion of the satellite, initially constant near 15.26 revolutions/day (the sun-synchronous value for inclination 97.37 degrees), has gone up steadily since late March 2007 (this date, the date of the reported malfunction, indicated by a vertical dashed grey line), indicating a loss of altitude. For comparison, the values of IGS 1B's still operational optical sister satellite IGS 1A, are shown as well (note how they remain constant due to the constant orbital maintenance manoeuvres this satellite continues to make):

click diagram to enlarge

Indeed, the perigee and apogee altitudes of the satellite as derived from the published amateur orbits, show a clear and increasing drop in altitude from March 2007 onwards (unlike the constant values of its still operational sister craft IGS 1A, shown as a reference in the diagram as well). Since the 2007 malfunction, the orbital altitude has already decreased by over 30 km, and the decrease is continuing at an increasingly fast pace:

click diagram to enlarge

As the loss of altitude starts right at the moment of the reported malfunction (late March 2007), it appears to be a malfunction affecting control of the satellite itself, not just it's radar system. With this is meant that the loss of altitude and start of orbital decay does not appear to be due to a controlled shut-down sometime after the remote sensing equipment malfunctioned. Instead, it appears that the Japanese operators have indeed truely lost control over the satellite.

When will it re-enter?

At the current increasing rate of orbital decay, it is clear that the satellite is now entering its last year of existence. Using Alan Pickup's orbital evolution software SatEvo and the latest IGS 1B orbit updates by McCants, IGS 1B's re-entry into the atmosphere is predicted to occur in about a year from now, around March, April or May 2012.

These predictions will probably shift a bit back or forth in the future, as the orbital evolution depends on a.o. solar activity (which is not constant and not well-predictable). But it is clear that somewhere in the first half of 2012, IGS 1B will come down.

Issues connected to the uncontrolled re-entry of IGS 1B

Similar to what was the case with the now infamous USA 193 satellite, the situation is that we have a satellite in a Polar orbit and likely containing a still significant reserve of fuel about to come down in an uncontrolled fashion.

Normally, when a spy satellite in Low Earth Orbit is at the end of its life, the last reserve of fuel is used to make the satellite deliberately re-enter in a controlled fashion, over a carefully chosen spot: usually the Pacific Ocean, where the re-entry can do no harm. This was recently done with the US radar spy satellite Lacrosse 2 for example (see here).

With a satellite that is out of control, like the infamous USA 193 and now this Japanese IGS 1B, that is however not possible. The satellite can basically plunge down anywhere on earth, and when remnants survive this re-entry, they can become a danger if the re-entry happens to occur over an inhabited area.

The latter danger was the official rationale behind the decision to destroy USA 193 in 2008 by means of a missile fired from the USS Lake Erie, just before the satellite would have come down on its own. Especially the fact that, due to the early malfunction of this satellite, there still was a tank with a considerable reserve of toxic hydrazine fuel on board, was given as a reason for the "shoot-down" (actually more of a "shoot-to-pieces"): the operation was called "Operation Burnt Frost" because the stated objective was to destroy the hydrazine reserve which, after two years of inactivity of the satellite, was likely frozen.

With IGS 1B, we might be facing a similar hazard in 2012. The satellite is bound to have a fuel reserve left, and quite likely a considerable reserve at that. (note added 24/04/2011: see however the post here, featuring an independant re-assessment by Ted Molczan)

IGS 1B passing through Canis venatici and the tail stars of the Big Dipper on 9 April 2011
click image to enlarge

As mentioned earlier, some sources list an intended life-span of 5 years for IGS 1B (and IGS 1A). It malfunctioned after 4 years, so one can expect that as a minimum there is at least enough fuel for a year left in the spacecraft.

But there are reasons to believe that the reserve of fuel left could in fact be considerably more than that.

The reason to think so is that, as mentioned earlier in this post, eight years after launch the IGS 1B sister craft IGS 1A is still actively maintaining it's orbit (see diagrams above). Mid-2008, the spacecraft manoeuvred to re-allign it's inclination to the 97.37 degree inclination orbital plane of subsequent IGS satellites launched from 2006 onwards. This indicates that 5 years after launch, it was (and up to this day probably is) still fully operational, and being primed for continued tasks. A CIA summary suggests an operational replacement by another IGS satellite was not effected untill at least mid 2010, over 7 years after its launch. As mentioned, amateur tracking data show that IGS 1A is still actively maintaining it's orbit as of April 2011, 8 years after its launch.

The implication is, that these IGS spacecraft actually have enough fuel reserves onboard for over 8 years of operation. As IGS 1B malfunctioned after only 4 years in operation, the implication of that in turn is that half or more of the original fuel reserves could still be left in the spacecraft (one factor however not easily calculated in with this, is the amount of fuel spent in the initial manoeuvering to obtain the desired orbit directly after launch).

That, a tank potentially still half full, is a considerable amount of fuel. (note added 24/04/2011: see however the post here, featuring an independant re-assessment by Ted Molczan)

Should action be taken?

The potential hazard of the onboard reserve of hydrazine fuel upon impact on earth was given as the primary reason to mount "Operation Burnt Frost" with USA 193 in 2008. As we might now be facing a similar situation with IGS 1B, it will be interesting to see if a similar drastic measure is taken, either by the Japanese (who own the same SM-3 missile system used for 'Operation Burnt Frost') or it's ally the USA, given that the latter has previous experience with such a complicated exercise. And if not, then the question will be: why in the case of USA 193, but not in the case of IGS 1B?

As was the case with USA 193 in 2008, the doomed IGS 1B satellite is in a polar orbit. It has a 97.3 degree inclined orbit, meaning that it is a potential danger to every latitude between 82.7 degree North and 82.7 degree South. This range of latitudes covers every inhabited spot on Earth, including all of the USA, Canada, Europe, Australia, Africa, Asia, South America and Japan.

While the amount of fuel left in IGS 1B is probably not as large (in the sense of amount of gallons) as it was in USA 193, a considerable amount of it nevertheless is very likely there, in the shape of what could be (note: in a "worst case scenario") up to a half full (and frozen) tank that might survive re-entry. Here, I should however mention that of course my assessment on the tank content is at best an "educated guess", and I could of course be wrong (only the Japanese can answer that point). (note added 24/04/2011: see however the post here, featuring an independant re-assessment by Ted Molczan)

Instead of watching this one quietly go down, I would prefer to see a good risk assessment done and either mitigating action taken, or 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.

Note added:
according to the
Japanese press, a second IGS radar satellite (IGS R2, 2007-005A) suffered a system failure in August 2010, 3.5 years after launch.

note: this post has been slightly edited in the afternoon of April 20, to better reflect the point that the "tank half full" assessment for IGS 1B is a "worst case scenario". Japan should give some openness in information to replace these "educated guesses" by more solid facts.

Friday 15 April 2011

IGS 5r flaring, and more USA 129 KH-12 in perigee

Over the past week I was able to observe on April 8, 9 and 12. I already reported on my April 9 observations of the new USA 227 (NROL-27) geostationary SDS here.

On April 12, I observed the Japanese optical reconnaissance satellite IGS 5A (09-066A) and the rocket that launched it, the IGS 5 rocket (IGS 5r, 09-066B), as well as the old American experimental satellite MSX (96-024A).

To my surprise, the IGS 5 rocket treated me on a bright slow mag 0 flare at about 20:43:27 UTC while it was making a pass in the east, near the tail of the Big Dipper. Below image shows the slow flare, with as an inset a second image made 20s later, showing it at its more usual brightness:

click image to enlarge

displayed a brief modest flare as well (mag. +1) at about 21:28:43 UTC.

IGS 1B (03-009B), another, older (and now defunct) Japanese IGS, was captured as well ( I will post more on IGS 1B shortly, probably at the end of next weekend, as it is coming down within a year from now):

click image to enlarge

The KH-12 optical reconnaissance satellite USA 129 (96-072A) was still making near-perigee passes over the SatTrackCam observatory, resulting in fast passes and long trails. I had to revert to the 24 mm wide-angle lens to avoid the object running out of the FOV.

Below are two images showing it ascend over the rooftop of the SatTrackCam observatory. The first image shows it in the front body of Leo: the second image shows the head and front body of Leo at left, Castor and Pollux in Gemini at right, the head of Hydra in the bottom, and the trail of USA 129 close to the M44 (Praesepe) cluster in Cancer:

click images to enlarge

Monday 11 April 2011

On the NROL-27 mission patch, and the satellites' geographic position at 30.4 West

Yesterday, I posted my first image of NROL-27 / USA 227, the SDS satellite launched March 11th. It is located at 30.4 W, over the Atlantic.

With that knowledge on the geographic position of this geostationary satellite, and hindsight, I have started to wonder whether there is a connection to the design of the mission patch:

As discussed before, the patch features a Gryphon (mythical creature, half lion, half eagle): with a lion (and the constellation Leo, the lion) between its legs, and reaching for an eagle (with the constellation Aquila, the eagle).

Realizing the eagle could be a metaphor for the USA, I suddenly realized the lion could be a metaphor for Africa.

This is interesting given the position and role of USA 227 / NROL-27 over 30.4 W, the Atlantic. In this position it connects Africa, to it's east, with the US, to its Northwest.

Is this what is depicted in the patch: the Gryphon (NROL-27) reaching from Africa to the US?
This would be the role of an SDS satellite: relaying data from reconaissance sats over Africa towards the USA (see also here).

If not intentional, than this is a very cool coincidence.

Sunday 10 April 2011

USA 227/NROL-27 at 30.4 W: a Gryphon in Hydra

NROL-27, a secret NRO payload that is probably an SDS communication satellite (see also here) was launched on 2011 March 11th.

On April 6th, Peter Wakelin made the first observations of the new object. The orbit (by Ted) places it at 30.4 W, over the mid-Atlantic in front of the Brasil coast, in a 5 degree inclined orbit, placing it low in the southwest for me, at an altitude of about 20 to 25 degrees.

click map to enlarge

Yesterday evening was a very clear evening, and based on Ted's preliminary orbit I photographed it, using the Carl Zeiss Jena Sonnar MC 2.8/180 mm.

Below is (a part of) the image. The object, at that time a few degrees northwest of alpha Hydra, is bright and shows up well:

click image to enlarge

Launch patches for NROL-27 can be seen in an older post here.

Note added 12/04/2011: a follow-up discussing a possible relation between the NROL-27 mission patch symbology and the satellite's geographic location can be found here.

Thursday 7 April 2011

Bright and fast KH-12 USA 129 zapping through perigee

Yesterday evening was clear, and I observed the KH-12 Keyholes USA 129 (96-072A) , USA 186 (05-042A) as well as the SAR satellite Lacrosse 3 (97-064A).

USA 129 was making a pass at 40 degree altitude in the east, at an altitude of only 303 km only minutes from passing through perigee. As a result, it was bright and very fast, zipping through the sky at notable speed: very cool to watch. It resulted in two long bright trails on the images. Two strays were captured as well: a very faint Russian rocket stage (84-067B) in one image, and a brighter Russian rocket stage (Kosmos 1484 r, 83-075B) in the second. The latter cruised up parallel to USA 129, being overtaken by it when both were passing through the tail of the Big Dipper. See the image below, where the longer brighter trail (the lower one of the two) is USA 129, the other the Russian rocket stage:

click image to enlarge

KH-12 USA 186 passed through the same sky area 20 minutes later, but at a much different altitude (830 km, against only 303 km for USA 129). The clear difference in trail length this generates, is shown by the image below, which is a stack of the two images of 19:41 and 20:03 UTC:

click image to enlarge

Sunday 3 April 2011

Sense and non-sense about the X37-B "Space Plane"

Quite some non-sense is appearing on the internet regarding the USAF's classified X-37B "Space Plane".

Most of this non-sense concerns the orbit of the X-37B and it's presumed extra "manoeuverability". Some typical examples can be found in the comments to this Slashdot coverage of the second X37-B flight (OTV-2), and I have seen similar misconceptions pop up in the comments to many other web-articles as well.

1. "Orbit targets Libya"

First: the claims that the current 43 degree inclination orbit for X37-B OTV-2 (and the 39 degree orbit for the previous OTV-1 mission) have been chosen to maximize coverage of a particular target, e.g. Libya. This "argument" stems from the difference with the more typical Polar orbit (60 to 90 degrees inclination) of reconnaissance satellites like the Keyholes and Lacrosses.

However: in terms of reconnaissance opportunities for any given location within the bounds of the orbital inclination, a 43 degree inclination orbit gives you no advantage over a polar orbit. On the contrary, while a polar orbit brings any latitude within reach for reconnaissance, a 43 degree orbit does not, as latitudes above 43 degree are less well covered (and far North or South latitudes aren't covered at all).

Note that for targets below 43 degree latitude, it really doesn't matter whether the satellite is in a 43 degree, 60 degree or 90 degree (polar) inclination orbit: all these orbits will bring such a target in reach, and the 43 degree orbit has no extra benefit compared to a 60 or 90 degree orbit at all in terms of target coverage.

Below diagram shows you the number of passes bringing Tripoli in range for 3 April 2011, for the X37-B as well as the KH-12 (polar orbit) and Lacrosse (57/67 degree orbit) satellites:

As can be clearly seen, the 43 degree inclined orbit of the X37-B does not result in many more passes compared to the other satellites in higher inclination orbits.

There is at best a marginal advantage over a true 90-degree polar orbit (the KH-12 Keyholes), but only marginal: and compared to the 57-67 degree orbits of the Lacrosses, the advantage in terms of number of passes over Libya is nil.

The maps below show the geographic coverage by a polar orbit (USA 186, a KH-12), a 57-degree orbit (Lacrosse 5) and the 43 degree orbit of the X37-B OTV-2. Limits of the geographic coverage of these satellites is indicated by the red lines: all locations inbetween these lines (the span of latitudes indicated by the red double arrow lines) get covered: where the limit is, is determined by the inclination of the orbit.

As the earth surface rotates beneath the orbital plane, strips of land get covered orbital cycle after orbital cycle. The X37-B does this in the same way as the other, "conventional" satellites.

Any given location inbetween the red lines on the X37-B map gets as well covered by the other satellite's higher inclination orbits: see also the previous diagram.

So it is nonsense to think that the 43 degree inclination orbit has been chosen to have a "better" look on a target near 43 degree latitude: a 90 or 60 degree inclination orbit will cover such a target just as well.

Instead, the 43 degree inclination has probably been chosen to maximize coverage of the X-37B orbit by US tracking and control facilities. So, it is a very prozaic explanation connected to the experimental nature of the craft, and the fact that it frequently re-boosts (it has to: it is in a low orbit and hence subject to quick decay).

2. "Manoeuverability"

Another frequent non-sensical remark about the X-37B is that it supposedly would be "more manoeuverable" than the typical reconnaissance satellite: and somehow able to "quickly get over a target" if necessary.

Again, this is a wrong view on how orbital dynamics and the dynamics of target coverage work. The X37-B might have wings and behave like an airplane in the atmosphere near landing: but in space, it is just a satellite subject to the same orbital laws as any other satellite. Like any satellite, it will cover any target within reach of the orbital inclination at least twice a day. And you just don't "steer" a spaceship to a target within an hour: it is not similar to flying an airplane (unlike suggestions in Battlestar Galactica or Star Wars). You change the orbital period and/or inclination and this determines when and how the satellite (X37-B in this case: but it is the same for any other satellite) will encounter a target, about twice a day (I say "about", because it actually concerns a number of passes centered on two times each day, 12 hours apart).

Below illustrations show this. The people who seem to think of the X37-B as a highly manoeuverable "plane" in space, are thinking along the lines of the first picture. That however, is not how it is! The second picture shows the true orbital movement of the X37-B, and as the pictures for Lacrosse 5 and USA 186 below that show, this is not different from the orbital movement of a "regular" reconnaissance satellite in any way:

Also take note of the fact that both on the previous mission and so far during this mission, the inclination of the X37-B orbit remains stable. It is not changing orbital plain repeatedly

The X37-B frequently makes small orbital maintenance manoeuvres (it has to, because of the quick rate of orbital decay at it's orbital altitude). Please note that, contrary to assumptions to the contrary often made, "conventional" reconnaissance satellites like the Keyholes and Lacrosses frequently manoeuvre as well. They have to, to maintain their orbital constellation, as zonal harmonics and atmospheric drag (even at their altitudes!) would quickly change their orbits otherwise, making them drift from the intended orbits.

Nothwithstanding this frequent manoeuvring (they do so multiple times a year) they stay operational for many, many years (Lacrosse 2 was finally de-orbited last week after being operational for 20 years, with very frequent manoeuvering during those 20 years).

So the X37-B doesn't really have much of an edge in sense of "manoeuverability" over any other satellite, contrary to what many people seem to think. The same in the sense of the benefits of "land and refuel" capabilities: other reconnaisance satellites operate many, many years including frequent manoeuvering.

The frequent manoeuvres the craft makes are manoeuvres to maintain orbital altitude and stay in a "frozen" orbit (an orbit that brings you over a target at the same time of the day, day after day, or each 2nd, 3rd or 4th day), and primarily this has to do with the low orbit (= high drag, high decay) the craft is in (this necessitates these frequent reboosts). It are not manoeuvres to change the orbit to quickly target new targets. That idea, is simply wrong and originates with people who have no clue about orbital dynamics in space.

The only real edge the X-37B has over other satellites is that it enables you to sent up and then retrieve payloads. For the rest, it cannot do anything more than any conventional satellite can do.

Saturday 2 April 2011

Lacrosse 2 is no more.....

A number of non-detections over the past week have confirmed that the classified US SAR satellite Lacrosse 2 (91-017A), the oldest of the still orbiting Lacrosses, has been de-orbited on or around March 26th.

The first to note Lacrosse 2 absent was Russell Eberst in Edinburgh on March 30th - incidently, the very person who also saw it first in March 1991.

This prompted a watch by other observers, including me, who all confirmed the "no-show" of Lacrosse 2.

In the evening of April 1st, I conducted a photographic watch between 19:44:00 and 19:53:00 UTC, keeping continuous coverage of a 18 x 24 degree FOV centered on the nominal position predicted for the satellite for 19:47:30 UTC. Nothing was recorded (another Lacrosse, Lacrosse 4 (00-047A) was recorded in the images when it passed through the same area at about 19:46 UTC).

As it now transpires, probably the last person to see Lacrosse 2 alive was Pierre Neirinck in France at March 25th, 20:19 UTC. Another observer failed to see it on March 26th: quite likely, it was de-orbited only a few hours and orbits after Pierre's observation.

Launched on March 8th, 1991, Lacrosse 2 has been operational for almost exactly 20 years: a long period of active service indeed.

Below are a number of archive images of Lacrosse 2 taken by me in 2008 and 2010. Goodbye, Lacrosse 2, you always were such a nice bright satellite to track.....

click images to enlarge

Friday 1 April 2011

NROL-34: Odin and Frigga

NROL-34 is slated for launch from Vandenberg on April 12th. The Atlas V 411 will launch a secret payload for the NRO: some independant analysts suspect it is a Trumpet SIGINT (of the same type as USA 184 and USA 200), to be launched into a Molniya type orbit.

The mission patch (below) shows the Scandinavian God Odin, recognizable by the eye-patch and the raven on its shoulder. Odin goes accompanied by two raven, and offered an eye to the dwarf Mimir in order to be allowed to drink from the source of Wisdom. As a God he personifies Wisdom, Strength and Battle. Note how these topics come back in the rim text, and how "Wisdom" is a good metaphor for SIGINT:

click image to enlarge

The battle axe could be a stylized version of a satellite with a radio dish (e.g., SIGINT).

The launch patch (below) features Frigga. Frigga is the wife of Odin, and the name as such is probably attached to the launch vehicle:

click image to enlarge

The latter patch is of very similar design to a number of other recent patches (NROL-41 FIA Radar 1, see patch here, and below; and NROL-49). I like this recent new design style, they look much better than the sometimes very generic other recent NRO and USAF Black Space patches.

Note how (as with the other mentioned designs) some letter codes are included in the blue "vermicelli" filling the Earth globe: one can recognize "NROL" (bottom), "Frigga" (top) and what could be a name, "Galth" (?), or possibly "Caltech".

Below are the two mentioned launch patches for NROL-41 and NROL-49 which show a similar design. All three have the earth globe, setting or rising sun (NROL-41 has the setting sun, and this might signify the retrograde orbit of the FIA Radar: note how NROL 49 and the NROL-34 patch have a rising sun), and a heroine/Godess (the Devil in the NROL-49 patch is female, and all patches feature female names: Gladys, Betty and Frigga); plus similar rim text designs:

click images to enlarge: