20 October, 2011

Space debris

This Sunday another Satellite is due to come crashing down to earth. The German ROSAT satellite finished its service in 1999 after nearly 7 years more service than was originally planned. It was planed that the satellite that was launched in 1990 would function for 18 months but was only shut down in 1999. ROSAT was designed in the 1980's when the end of life of satellites was not really considered so it was not built with its own propulsion system, like modern satellites, which enables their re-entry conditions to be controlled to ensure that they land in an uninhabited area of the globe. 

The chance of this satellite causing harm to anyone is higher then the previous uncontrolled decent at 1 in 2000. Some confusion was noted in the run up to the UARS decent, this is not the chance that you as an individual will get hurt, but that someone somewhere on the planet will get hurt. 

The satellite is predicted to fall somewhere between 53° N and 53°S which unfortunately covers most of the worlds landmasses. The exact location or timing cannot be predicted at the moment due to changes in the radiation from the sun causing the upper atmosphere to expand and contract changing the 'pull' of the atmosphere on the satellite. 
Increased solar activity expands the atmosphere and increases the 'pull' advancing the descent of ROSAT by a small margin each time. 

Following ROSAT_Reentry on twitter helps to get an understanding of when the satellite will enventually fall, the current prediction is Space-Track #ROSAT Predicted Decay 2011-10-23 05:03 GMT ± 48 Hours as @ 2011-10-20 08:06 GMT

With a window of +/- 48h there is still a large margin of uncertainty. But it does look likely that the satellite is no longer going to be visible from the UK, unless the descent is at the right  time so that some  of the burn up in the atmosphere is visible. 

In other space related news, look to the skys this evening as there is supposed to be some Orionid activity. Meteors to you and I :D

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