Friday, July 25, 2003

Lyakhov & Aleksandrov:

Twenty years ago*, aboard the venerable Salyut 7 Soviet space station, cosmonauts Vladimir Lyakhov and Aleksandr Aleksandrov heard a sound no space-farer wants to hear: CRACK!

The cosmonauts started emergency evacuation procedures, fearing that the hull had been pierced and they were losing air. After a few minutes it became clear that the air pressure was not dropping, and they began to explore the station to find the cause, eventually finding a 3.8 cm impact crater in an observation port. Luckily, the impact had not pierced all the layers in the window.

This particular incident was attributed by the Soviets to the Delta Aquarid shower, but there is also the possibility that it was caused by man-made space debris -- something Lyakhov himself later contributed to by casting off junk during his November 1 1983 spacewalk. All subsequent Russian space station modules have had armored covers over their view ports that are supposed to be closed when not in use.

Aleksandrov later went on to work for the Energiya Design Bureau on rescue systems, and in 1989 he compiled some interesting numbers on spaceflight 'anomalies' during the Vostok, Mercury, Voskhod, Gemini, Soyuz, Apollo and Soyuz series:
  • over 30% were due to human failures
  • 21% were control system failures
  • 85% had no impact on the mission
  • 6% required the use of backup systems
  • 2.5% were self-correcting
  • 0.5% had both the primary and secondary backup systems fail


Pity there is no comparison with Shuttle.

There is an amazing amount of debris in space around the Earth. J-Track 3D is the best Java applet illustration I have seen of the sheer number of satellites that orbit the Earth (and for teaching orbital mechanics, for that matter). If you consider the number of tiny particles that each rocket booster generated in placing these items in orbit, you can get a general idea of how much of a man-made hazard we have put into orbit. Tiny, brilliant pebbles indeed.

*There is some disagreement in the literature over whether this happened on July 25 or July 27.

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