Wednesday, September 26, 2012

RUSSIAN DEBRIS THREATENS THE International Space Station

The Kosmos 2251 military spy satellite launched by Russia in 1993, decommissioned two years later, it now may pose a real threat to the ISS. In looking into how this could happen and what processes are gone through when a satellite is decommissioned.

First steps are to remove fuel and to reduce pressurant to safe levels. Usually this results in a loss of attitude but since the satellite can still receive commands in a non-nominal attitude this shouldn’t present a problem. Though not always a concern the team might drain the battery or simply disconnect the battery once it is no longer needed. The final need is to turn the satellite off. And since attitude is not needed any longer (usually a new satellite takes its place), so the final command – to turn the power converter off- is sent and ‘no further action is necessary.

After the decommissioning process the satellite just flies its orbit, usually Geosynchronous or Polar and the orbit slowly degrades until it falls in the Pacific somewhere. I checked various satellites to get the average lifetime and the Kosmos seems to have gone longer than most though there is no real set time.

Have any satellites collided in space since there are so many? Yes. In 2009 a Russian communications satellite struck a US one in an accidental collision. Actually this one. It crashed into our satellite and broke into many pieces and now those pieces threaten Russian & Americans astronauts onboard the ISS.

So what can be done? The ISS will have to maneuver out of its way.

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