Sunday 27 January 2008

USA 193: life and death of a spy sat (twice updated 29 Feb)

UPDATE 29/02/08 (II): New NOTAM warns aircraft for decaying USA 193 debris between now and March 9th. See my post here.
UPDATE 29/02/08 (I): NROL-28 launch delayed because of USA 193 debris risk. See my post here
UPDATE 27/02/08: Fragments of USA 193 still in orbit and observable: see my post

21/02/08: THEY DID IT!
more below.

UPDATE 20/02/08:
Sources say rough seas in the Pacific might prevent taking a shot at USA 193 on Wednesday/Thursday night.
UPDATE 19/02/08: John Locker has drawn attention to a second NOTAM for the same area, one day later. This is probably for a possible second attempt if the first one fails.
UPDATE 18/02/08: Ted Molczan has drawn attention to a NOTAM issued by the US Government that might point to a possible ASAT attempt on USA 193 on Feb 21, 3:30 UTC as USA 193 passes near Hawaii. See below for more.
UPDATE 17/02/08: Russia has now accused the USA that it is all a cover-up for an ASAT test..
UPDATE 14/02/08: News reports today suggest the US military has serious plans to shoot the satellite from orbit before the time of the expected decay, and are now confirmed by the US military. See the note at the end of this post.

Latest (21/02): USA 193 destroyed with a missile! News comes in that the American Navy last night (20/21 Feb) made a successful attack on USA 193, destroying it into multiple pieces with a SM-3 missile shot at 3:26 am GMT from the USS Lake Erie.

Link: Missile Intercept. Video released by the Pentagon

Amateur observers on the Canadian west coast report observing a spectacular shower of fragments re-entering in the atmosphere over Canada within 10 minutes after the successful attack. More fragments might come down today elsewhere along the former satellite's flight path.


Main background story

The weekend of 25 January, after what appeared to be an "organized leak" by a US government agency, the imminent decay of the failed reconnaisance satellite USA 193 (06-057A) gathered press attention.

USA 193 was launched on 14 December 2006 as NROL-21 with a Delta II rocket from Vandenberg Air Force Base in California. It somehow failed and went "dead" shortly after launch. There is no sign that its orbit has been under control since, and amateur satellite trackers were already long aware that the satellite orbit was decaying and the satellite doomed due to this.

Some sources suggest failure of an onboard computer as the problem with the satellite. Imaging by John Locker shows no sign of solar panels, which brings in the option of a power failure due to a failure to deploy the panels. Ted Molczan has suggested that an onboard computer boot failure prevented the panels from deploying, causing a loss of power when the batteries ran down, and notes that this tallies with the fact that radio signals from the satellite were logged by amateur radio trackers for 1.5 days after launch but then died down.

Orbital plane of USA 193 (06-057A)

The orbital inclination of the satellite was 58.5 degrees meaning it roughly covered all locations between 60 degrees north and south latitude. It was probably intended as a test platform for a new generation reconnaisance sats about the purpose and construction of which little is known. Sources differ on whether it could have been an optic or radar reco platform, or maybe both. According to the usually knowledgeable, it was a radar reco sat intended to replace the Lacrosse system and probably weighing about 3300 kg (which is only 1/3rd of the 9000 kg reported in the press for the object). Imaging by John Locker from September 2007 suggests the satellite was about 4 meters large. The official NRO press release at the time of the launch only stated that "the satellite launched will provide invaluable intelligence data to support the war on terrorism".

USA 193 was a satellite which was part of my regular observing program, observed and imaged by me several times. It was a bright naked eye target, reaching magnitude +1 under favourable illumination conditions, zipping across the sky at a spectacular high speed due to it's low orbital altitude. At the end of it's one year "life", it's perigeum was already below 250 km above earth surface and in its last weeks it was coming down fast (see diagram below).

Below diagram shows the altitude decay of the perigee (and apogee) of the orbit over time, and how the decay rate was accelerating. The final rate of decay was over 1 km/day.

(data in the diagram are derived from published orbits
based on amateur observations including mine,
calculated by McCants and Molczan:
last updated 23/02 with final epoch 08052 orbit)

The last orbit calculated by Molczan (08052.017 epoch) measured 242 x 257 km and provided a nominal value of the expected decay date of March 12th, but this value has an uncertainty of many days. On February 21st at 3:29 GMT, the satellite was destroyed by an SM-3 missile, making the subject of the expected decay date moot.

The large media attention to the imminent satellite decay was somewhat surprising, and the same goes for the fact that the US government itself has brought the imminent decay to the attention. We failed to see the reason for this. Among (amateur) satellite observers it was already known for a long time that this decay was about to happen. Moreover, the question is how much of an extra risk this decay really posed compared to other decays happening several times a year. Chances that the impact of remains, if any, posed damage to property or persons are minimal. Only if someone comes into direct contact with hydrazine fuel remnants, risks are involved. With several earlier occasions of satellite or rocket fuel tanks reaching earth surface intact in the past, this so far never has happened. In fact, the chances that a random passenger aircraft with fuel tanks will drop on your head today, are considerably bigger than the chance that USA 193's fuel tank would have done.

The whole situation as to the "why?" of bringing the satellite decay (and later the ASAT-attack on it) so prominently into the news definitely has open questions.

Some wild speculation about the potential presence of a nuclear (Plutonium based) power system on board has been popping up here and there, e.g. in the discussion on Slashdot, in The Observer and here. There is no reason to think the latter is really likely according to several specialists.

*** "Shooting it down" ***

On February 14th, the US military announced that they had plans to shoot the satellite down with a missile, "to reduce the danger to human beings". This gives a new twist to the story.

Official sources state that here is about 450 kg of hydrazine fuel (a very toxic substance) on board, and an expected 1100 kg (about one tonne) of debris of the satellite itself might reach earth surface intact.

The plan was (and we now know they did it too) to intercept the satellite in the week following February 20, using one or more SM-3 intercept missiles fired from naval vessels in the North Pacific. The SM-3 missiles need to be modified for this task as they normally target object at lower altitude on a ballistic trajectory instead of a true orbit.

The term "shooting it down" is, by the way, a bit misleading here. In reality, what happened is that the impact of the ASAT weapon broke up the satellite in many pieces, which will continue their orbit around the earth as a debris cloud. Due to their higher surface-to-mass ratio, smaller debris pieces will experience increased drag, which will make them decay earlier than the intact satellite would have.

On Feb 18th Ted Molczan has drawn attention to a NOTAM, issued by the US Government, that pointed to a possible ASAT attempt on USA 193 on Feb 21, 3:30 GMT.


AN AREA BNDD BY 3145N 17012W 2824N 16642W 2352N 16317W 1909N 16129W 1241N 16129W
1239N 16532W 1842N 17057W 2031N 17230W 2703N 17206W SFC-UNL. 21 FEB 02:30 2008
UNTIL 21 FEB 05:00 2008. CREATED: 18 FEB 12:51 2008

The NOTAM excluded an area just west of Hawaii over which USA 193 would pass near the time above (see below map, showing USA 193's approximate position at 21 Feb 3:30 UTC):

(click map to enlarge)

An ASAT attack at this moment in this ground track would mean that within minutes the resulting debris cloud would come into range of ground tracking stations at the US West coast, where twilight would just have ended (and with the full moon being in eclipse at that moment (!) and low in the sky anyway, it woild be no hindrance to optical tracking facilities for tracking faint fragments). Next the debris cloud would pass over the arctic region of North America, where several radar tracking facilities exist.

Also, any quickly re-entering fragments would come down over the barren Canadian Arctic, rather than pass over highly populated areas. For a full orbit following an attack at this location, debris will not pass over significant inhabited land, as can be seen in the map below showing the trajectory of the satellite.

The marked position in the map below near Hawaii is for 3:30 GMT (Feb 21st), the moment of intercept, and the satellite (and its fragments after intercept) moves "up" along the marked line in the map, towards North America, over the Canadian arctic and then the Atlantic Ocean:

(click image to enlarge)

Hawaii itself would provide valuable tracking facilities prior and after the intercept.

On February 21st 2008 at 3:29 GMT (and quite along the anticipation described above), the satellite was indeed successfully destroyed with a SM-3 missile shot at 3:26 am GMT from the USS Lake Erie.

Link: Missile Intercept. Video released by the Pentagon

Amateur observers on the Canadian west coast report observing a spectacular shower of fragments re-entering in the atmosphere over Canada within 10 minutes after the successful attack. More fragments might come down today elsewhere along the former satellite's flight path.

As mentioned, there are questions as to the "why?" of the high profile media publicity of this all. Some observers have started to wonder whether it might all be a very cleverly orchestrated setup by the US Government, designed to get maximum global attention to an ASAT demonstration. Indeed, Russia has publicly accused the USA of covering-up a true ASAT-test with this.

If we entertain that notion for a moment: with this ASAT demonstration, they would hit three birds with one stone:

a) They send a high profile geopolitical message to China, and to the homefront, in answer to last year's Chinese ASAT test on Fengyun 1C. Basically, this message says: "you/they can shoot satellites out of the sky, okay. But remember we can too, so don't even dare to try ours or we will do the same to yours/theirs..."

b) They give some rendement to an otherwise worthless assemblage of several millions of Dollars worth of inoperative scrap metal now uselessly orbiting this planet.

c) it is an ideal opportunity to test their anti-satellite and anti-ICBM weaponry

I can't really comment on the value of this speculation, as I am not an expert on military geopolitics. A valid argument against (a) raised by some is however, that shooting down USA 193 at 250 km altitude is not quite the typical situation for an ASAT attack as this is much lower than the normal operational altitude of satellites. It is known from the succesfull ASAT test on the Solwind satellite (which orbitted at 550 km altitude) which the USA carried out in September 1985 however, that the USA does possess the capability to reach higher altitudes. The problem with ASAT attacks is moreover not so much the altitude to reach, but rather to hit the (small, fast moving) target.

As a reminder that the USA is capable of this, the demonstration would suffice, and USA 193 is the ideal target for it. Because of its low orbit, the formation of a debris cloud such as happened with the Chinese ASAT demonstration early last year isn't such a concern. Because of the low altitude, and unlike with the Chinese ASAT test, most if not all debris pieces would re-enter into the earth atmosphere within days after the ASAT attack, and therefore will not propose a real hazard to other satellites. This means the USA can use this object as a target without fear of being called hypocrits after their fierce criticism of the Chinese ASAT test last year, which created a high altitude, long lasting debris field which does provide a threath to other satellites.

Here's an archive picture of a USA 193 pass over Cospar 4353, which I shot on April 3 2007:

(note: all images in this post may be used for informational purpose, provided the source is acknowledged)

(click image to enlarge)

Saturday 26 January 2008

Thin clouds spoiled the sats, but nice Moon this morning

When I came back from diner with friends around midnight, it was nicely clear. So I set the alarm-clock to see if I could catch the NOSS 3-4 duo in morning twilight.

Alas, when the alarm clock went off it turned out to be thinly veiled and impossible to observe satellites. So instead I took photographs of the waning moon. The best one is shown below. Like a few days ago, this one was made by just holding the Canon Ixus compact camera with its front lens on the eyepiece of the Meade ETX-70.

(click image to enlarge)

Wednesday 23 January 2008

Of NOSS-es, strays and neighbours

Yesterday the 22nd of January started clear and ended clear, albeit with a near full moon. I did an observing session with the ETX-70 telescope in morning twilight as well as in the evening.

The result: positions on the NOSS 3-4 pair (07-027A & C), the NOSS 3-3 pair (05-004A & C) and the NOSS 3-2 pair (03-054A & C), plus stray observations of the ELINT sat USA 32 (88-078A) and the spent Russian rocket Kosmos 1171r (80-026B). I also observed the NOSS 2-2 C & D pair, but couldn't log points (There was only a short time to re-aim the telescope between this pass and the NOSS 3-3 pass, and it then took me just too long to verify I had the correct star field. I saw them pass the FOV but couldn't get to clock them in time.).

During the morning session I unintendedly startled one of my neighbours when she came out of her house and saw me on the courtyard with my telescope. She went into a panicky fit as a result. This was just as I was about to catch 07-027A. The resulting melée and the added unexpected appearance of 88-078A as a "stray" only 11 seconds before 07-027A make me suggest to use the 07-027A point with some caution (by the time of 07-027C I should have regained my composure).

Some time after the end of the evening session, I portrayed the nearly full Moon. Below image is a quick shot made by simply pressing the (non-removable) objective lens of my Canon Ixus compact on the eyepiece of my ETX-70 telescope. Some after-editing has been done to the image to bring out detail.

(click image to enlarge)

Sunday 13 January 2008

Lacrosse 2 manoeuvre, and bad luck with a stopwatch

Yesterday was a very clear day, so in twilight I set up the ETX-70 to gather positional data on Lacrosse 2 (91-017A), the NOSS 3-3 (05-004 A & C) duo and the NOSS 3-4 (07-024A & C) duo.

I had adapted the home-made piggyback camera adapter slightly, so it can also funtion as a rest for my 5 mw green laserpointer. The drawback of the ETX-70 is that it doesn't come with a finderscope, so I use the laser to point the telescope. A 5 mw green laser gives a tens of meters long visible beam at night pointing to where you point the scope if you shine it parallel to the scope tube. Simple, and works like a charm.

Unfortunately, after succesfully observing passes of NOSS 3-3 A & C and Lacrosse 2 I must have hit a wrong button on the stopwatch by mistake. When I had pointed the telescope to the point near where NOSS 3-4 A & C should pass and took up the stopwatch, I discovered to my horror that it was no longer running and had no lap times in it's memory! I lost all gathered points so far.

Next, in the confusion of having to start up the stopwatch anew just before the NOSS 3-4 duo pass, I lost that pass.

Now, I can't quite stand such things happening, it makes me very irritated for a while. Luckily my neighbours have double-pane glass, so probably they did not hear my swearing...

What saved the night was that before turning to the telescope, I had triggered the Ixus camera in addition during the Lacrosse 2 (91-017A) pass. The trail showed up faint but well enough defined to measure against the late twilight sky, which meant I had an image providing two positions.

After data reduction, it turned out that the satellite was 17.3 seconds early relative to Mike's 07357.17849791 TLE. On the 6th of January, the difference to this TLE was 1 second. So I reckoned 91-017A must have made a manoeuvre recently. Which, it turns out, it indeed did, a small manoeuvre changing the mean-motion slightly on or near the 6th. What I had missed was that Mike had just issued and update of the 91-017A orbit incorporating the manoeuvre yesterday morning.
That 91-017A still does manoeuvre, points out it is still alive and probably still being used for reconnaisance almost 17 years after it was launched.

(click image to enlarge)

Lacrosse 2 (91-017A) crossing through Cygnus 17.3 seconds early

I set my alarm-clock to see if it would still be clear in the morning (allowing me in that event to catch amongst others Progress M-61). But alas, it had become overcast.

Thursday 10 January 2008

NOSS-es, Lacrosses and ISS

Yesterday evening the 9th it was clear in twilight, but clouds came in a while later. Nevetheless there was time enough to get out the ETX-70 again and bag the NOSS 3-4 duo (07-027A and 07-027C), the NOSS 3-3 duo (05-004A and 05-004C) and Lacrosse 3 (97-064A). In total, 7 points were obtained. In the morning of the 10th, I observed the International Space Station just before clouds again interfered.

About 3 minutes before the NOSS 3-4 duo pass, another faint sat crossed the telescope field in a similar trajectory. I was just making a last check of the star field in view against a plotted map to ensure I had the correct location in view, so hadn't the stopwatch in my hands. At first I was a bit worried it was one of the 07-027 objects but very early, so I was relieved when 3 minutes later the real 07-027A sailed into the FOV.

Later that night it cleared again. Below is the image of the ISS I shot a few hours later, during the morning hours. It can be seen passing from Corona borealis into Hercules. It was bright, around mag. -4. My main intended target for that early morning was Progress M-61, but clouds (already visible in the ISS image) intervened.

(click image to enlarge)

Tuesday 8 January 2008

More NOSS 3-4

It shortly cleared around twilight this evening. There were flying clouds and some thin high altitude streaks in the sky, but I managed to get a pass of the NOSS 3-4 A and C pair (07-027A, 07-027C) and get two points on each as they passed close to mu Andromeda. Like during my observ ations on the 6th, the sats had a clear yellow colour.

This time I had no trouble with handling the stopwatch to retrieve the logged timings any more. Also, comparing with other observer's results, my timings seem good, but I might need to work a bit on the cross-track error.

Shortly after the observation cloud cover returned.

Monday 7 January 2008

USA 193, first ETX observations of NOSS 3-4, and comet 17P/Holmes

Last two nights (the evenings of 2008 Jan 5 and 6) were the first nights I tried to do visual position determinations on fainter satellites. Targets were the NOSS 3-4 A & C pair (07-027A & 07-027C).

The Meade ETX-70 (see picture below), a small and compact 7 cm/f 350 mm (F5) rich-field refractor, turns out to be a very nice instrument for satellite observing. It was cool to see 07-027A sail majestically in and out of the FOV, half a minute later followed by 07-027C. At 14x magnification with the 25 mm eyepiece, the FOV is over 3 degrees with (from the light-polluted mid-town location Cospar 4353 in Leiden center) a limiting magnitude at mag. +9.5.

(click image to enlarge)

The Meade ETX-70. Attached is a home-made piggyback mount for my camera

I had some problems operating my (new too) stopwatch though. During the Jan 5 attempt, I pushed a wrong button when I wanted to read out the memory, resulting in the loss of all 4 points. During the Jan 6 attempt, I did the same with 2 points on 07-027A after I had succesfully retrieved 2 points on 07-027C (plus another point on the same object taken during an earlier pass). Evidently, I still need some practise. Logging with the stopwatch, estimating the fraction between two stars crossed, and operating Ted's Obsreduce software all went surprisingly well though.

On Jan 5th in deep twilight I observed USA 193 (06-057A) zipping by. I got two camera points on it but apparently the times are off. This failed (?) reco sat keeps being a fine object to view as it is bright and very fast. If it's orbit continues to decay as it does now, the object will end its life around the first week of April.

On Jan 6th I observed, apart from the NOSS 3-4 pair, also Lacrosse 2 & 3.

The evening of January 6th was very clear, and I used the ETX-70 to function as guiding mount for the Canon Ixus camera. Target: comet 17P/Holmes.

The comet has grown very large (about 1.12 degree currently) and vey diffuse. Below is a photograph showing the comet which is a stack of 39 images of 15 second exposure each. The open cluster in top of the image is M34, the bright star below the comet is Algol. Because the ETX-70 is on an alt-azimuth mount and the comet was near the zenith, where the effect is largest, some field rotation is visible in the stars near the image edges.

(click image to enlarge)