Sunday, August 08, 2010

The top ten orbital debris-producing missions of all time

This is recent data released by NASA's Orbital Debris Office.  As a result of over 4 700 launches since 1957, there are currently around 19 000 pieces of trackable debris.  Most of this derives from missions launched by the USA, the former USSR and China.  

The missions which produced the greatest quantity of debris are: 

Name                                Year        Debris          Cause of Breakup 
Fengyun-1C                    2007          2,841          Intentional Collision 
Cosmos 2251                  2009          1,267          Accidental Collision
STEP 2 Rocket Body       1996           713             Accidental Explosion
Iridium 33                     2009           521             Accidental Collision
Cosmos 2421                2008           509             Unknown
SPOT 1 Rocket Body     1986           492             Accidental Explosion 
OV2-1/LCS 2 Rocket     1965           473             Accidental Explosion 
Nimbus 4 Rocket Body  1970           374             Accidental Explosion
TES Rocket Body           2001           370             Accidental Explosion 
CBERS 1 Rocket Body   2000            343            Accidental Explosion

What's interesting to note about this is that the most frequent source of debris in the top ten is rocket bodies, and I presume this is largely due to residual fuel (there is a large amount of literature on the problem of passivation at the end of mission life).  And six are also within the last ten years, suggesting that, despite guidelines for limiting the creation of orbital debris being around for a decade or more, they may not be very effective ...... Note also that there are only two accidental collisions in this list, which supports my argument that the risks posed by large objects that may have heritage value, if they are left in orbit,  are not as great as we might think.

Of course this is only the top ten, and a more thorough investigation of the figures may be illuminating.

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