Spacewalk thruster incident alarms NASA

The mysterious 'phantom torque'
In Houston, NASA officials have set up a special team to investigate the incident. The group will determine what changes may be needed in U.S.-Russian control procedures before the next spacewalk in two months.

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.

"We don't have agreement," Geyer said. 

While the NASA TV commentator described the “phantom torque” as appearing “when the crew is imparting a force” to the outside of the station, a simple familiarity with Newton's Laws of Motions shows that this explanation is spurious.

There is no force without a counterbalancing force. Any push on the outside of the station that made the station turn away from its desired orientation, would require the pushing party -– the astronaut –- to go flying off into space. Just banging on the outside, as long as you are securely attached, creates no rotational forces.

What is actually happening is that something besides the spacewalkers’ motion is creating a genuine force against the side of the station. Somehow, a small amount of material is being sprayed away from the station, enough that over time the station builds up an unwanted rotation.

As reported on last year by MSNBC.com, 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.”

Almost all of the work to be conducted during the crew’s second (and final) spacewalk will take place at the far end of the Russian segment, where the disturbing torques from their spacesuits will be greatest -– and where they will be closest to the Russian rocket thrusters that will have to be activated to counter these forces.

At the very least, NASA may reconsider its attitude toward performing such spacewalks without television coverage.

Geyer, for one, said he did not believe that the existing plans need to be changed: "We had clear agreement on flight rules and operations plans, on which worksite had thruster inhibits and which did not," he said. Those rules can work as long as ground controllers can be better aware of the location of the spacewalkers.

Many of the initial rumors expressed concern about an apparently complacent treatment of the potential exposure. Some space workers believed that officials had assumed, in the absence of proof, that there had been no contamination. This is the opposite of the proper attitude of assuming the worst until a better appraisal could be justified. Such thinking would remain too frighteningly similar to the one that failed to prevent and then failed to recognize the factors that killed seven astronauts only two years ago this week.

That isn't what happened, however, Geyer said. Nobody in Mission Control made any convenient assumptions about contamination not occurring, he said; the potential for a dangerous exposure was never discounted.

In fact, he said, officials went out of their way to remind the returning spacewalkers to check for possible damage.

"The normal plan is that when the crew is ready to come back in, they look over each other's suits for damage or discoloration,” Geyer said. "And we specifically reminded them not to forget to do so this time."

Nothing unusual was seen, and when the men got back inside and opened their visors to sniff the airlock atmosphere, they noticed no unusual odors either.

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