Tuesday, April 22, 2008
A Dangerous Business
Traveling to space and back is still a dangerous business. We tend to get inured to the dangers as mission follows mission and nothing happens. It barely makes the evening news. It takes a disaster like Challenger or Columbia to awaken public interest. But every time a space mission succeeds it is the result of lots of hard work and attention to detail. Also a little luck.
This weekend a Russian Soyuz capsule returned from the International Space Station with three crew members on board: Russian Yuri Malenchenko, American Peggy Whitson and South Korean Yi So-yeon. They landed safely and in good health, but it was a close call. Their Soyuz capsule, workhorse of the Russian space program for forty years, had malfunctioned.
Each Soyuz spacecraft has three sections: an orbital module on top, a descent capsule in the middle, and a propulsion module on the bottom. To land successfully, the rocket engines in the propulsion module must fire to begin the descent, then the descent capsule with the crew members inside must separate from the other two sections for reentry. Only the descent module has a heat shield and is designed to survive reentry.
Early reports indicate that on Saturday the propulsion section failed to separate normally. As the spacecraft began its fiery reentry its hatch side was facing forward instead of the heat shield. Fortunately, the propulsion module finally separated before the heat damage became critical. The capsule then made a failsafe ballistic landing instead of its normal guided descent. This subjected the crew to about twice the normal G forces - almost ten times the force of gravity. The radio antenna was destroyed by the heat, so the crew could not communicate with Moscow's Mission Control. For almost half an hour no one knew where the Soyuz had landed or even whether the crew survived. To add to their troubles, the still-hot capsule ignited a grass fire upon landing which filled the cabin with smoke for a few minutes.
The Russians train every crew for such situations, however. Despite the fact that the craft landed on its side and despite the fact that he had just endured a 10 G reentry after six months in zero G, Malenchenko managed to free himself from his seat restraints and exit the capsule. He used a satellite phone to contact Mission Control. (One has been included on each Soyuz mission for just such a purpose ever since a similar off course landing occurred in 2003.)
Since they landed 260 miles short of their target, the first people to reach them were the astonished Kazakh locals. They helped the astronauts exit the craft and unload some of their equipment. Shortly thereafter the first Russian helicopters arrived. The astronauts were returned to Star City in Russia where they were examined and found to be healthy. Their capsule will now be examined for clues to the cause of the malfunction.
Some day I hope space travel becomes as routine as air travel, but that day has not yet arrived.