Tuesday, 1 February 2005

Not a Walk in the Park

As reported earlier, the 2-man crew of the ISS (International Space Station) has just completed a 5-hour spacewalk to do maintenance and construction.

Now, via An Eternal Golden Braid, a hint that things may not have gone smoothly.
Behind closed doors, the origin of what one source called a "major close-call incident" and NASA's reaction to it are the subject of concern within the space agency and between the space station's U.S. and Russian partners.

U.S. astronaut Leroy Chiao and Russian cosmonaut Salizhan Sharipov spent five and a half hours working outside the space station last Thursday, performing a series of assembly and inspection tasks. It was the first spacewalk of the mission for the pair, who are halfway through their six-month stay on the station.

During the spacewalk, the station's stabilizing gyroscopes repeatedly became overloaded with a mysterious torque, and they had to be relieved periodically by firing rocket thrusters located on the Russian half of the station. On at least one occasion, and contrary to agreed upon mission rules, these thrusters appear to have been activated when the two crew members were working dangerously close to them.

This put them at risk of both thermal damage from the thrusters themselves and, more likely, to chemical contamination from the fuel used by the thrusters. Even in small amounts, any fuel splashed on the space suits could render the air toxic in the station when the men returned from their spacewalk.

That neither of those events actually happened isn't reassuring to those at NASA who want to know exactly how close the men were to the thruster plumes. Engineers at NASA who have spoken privately with MSNBC.com say they are studying the incident all the more intently because the next scheduled spacewalk, in March, could expose the crew to even more hazards of this kind.
There's also a worrying degree of disagreement about the ISS's propensity to rotate faster than the gyros can handle.
Meanwhile, NASA and Russia have conflicting theories about the cause of the "phantom torque" that is trying to push the station out of alignment during spacewalks.
NASA believes this force comes from water vapor sprayed out the back of the Russian-made spacesuits to keep them cool. The Russians, however, do not want to blame their suits, and insist the force comes from slight air leakage from their airlock.

"Until it is resolved," a source e-mailed, "we'll continue to have this problem for every [Russian] EVA."
In a related article, clues to the the cause of the misbehaviour of the Oxygen generators may have been found.
A late addition to the spacewalk was the inspection of exterior vents for the main oxygen generator and air purifiers.

The Russian oxygen generator has broken down repeatedly, and engineers speculated its vent might be clogged or corroded. The air-cleansing equipment also has a history of malfunctions.

Sharipov found a large patch of dark, oily residue on at least one vent and a white substance "he described it as a honeycomb" on the oxygen generator's outlet. "They're going to be very good pictures," he said as he photographed the goo.
There's still an awful lot about long-duration space missions we don't know enough about.
As a platform for performing Space Science experiments, the ISS is a crock. The vibrations caused by crew movement are enough to completely bollix up most microgravity experiments. It's vastly expensive, and there's almost nothing a series of far cheaper ( as in 1/10,000 of the cost) satellites could not have handled better.
But it's the "almost" that's important. As a platform for figuring out how people can live and work on long-duration space missions, it's invaluable, irreplaceable. Also, and equally importantly, for working out the bugs in the management of International space missions. Far better to detect the screw-ups and valid "differences of opinion" (like the ones to do with the spacewalk mentioned above) while "safely" in Earth Orbit than to try to do the same at close to a light-second's distance (Luna) or even further.

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