Rise or Fall
2014 Aug 21
Thursday, Day 233
Phobos-Grunt - Reentry Watch
Re-entry occurred as anticipated 2012 January 15 and Phobos-Grunt was destroyed by the heat of friction with air molecules.
As the end approached, estimates homed in on a likely re-entry time but still covered several hours and, eventually, several tens of minutes. The final few days' estimates are listed here.
Spacetrack issued a message January 15 at 20:34 UTC and stated simply that it had decayed within the forecast period of 16:59-17:47 UTC. Then, on Jan 17 a Final TIP Message in full, standard format appeared, giving the location - it was shown as being issued Jan 15 at 17:53 UTC.
The final Phobos-Grunt orbit data is here.
There is a map showing the final ground trace here.
A Different Way of Looking At It
Here is the same information presented graphically but going back to December 1. Through December, estimates were drifting later with time suggesting that Phobos-Grunt may not have been following a natural pattern. Maybe there was still a degree of thruster operation occurring, acting against atmospheric drag. Alternatively, if it was still orienting itself towards the Sun, then the aspect that Phobos-Grunt presented to the direction of travel will have been changing as the orbit changed its angle to the Earth-Sun line. Around the turn of the year, the time drift ceased.
NOTE - the spread in estimated dates and times up to about Jan 12 was partly due to differing models being used by different sources, and partly to changes in forecasts for the 'Solar Weather' affecting upper atmosphere density. Change necessitated having to revisit the reentry estimate.
Charts on this page are produced using JpGraph.
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