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

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

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 intermittent detections when the object moves over tracking facilities, spread wide and far over a number of places around the globe. They do not have continuous coverage. They cannot track where they have no tracking 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?

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)

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

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

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:

Observing Fobos-Grunt on 30 November

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

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.

If rescue fails, Fobos-Grunt will reenter soon

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.