Astronauts Gennady Padalka and Edward "Mike" Fincke aborted their planned spacewalk outside the international space station yesterday after Fincke's spacesuit developed a malfunction minutes after the two men had left the airlock on a repair mission.
Russian controllers ordered both men back into the airlock when they noticed that the pressure in Fincke's primary oxygen bottle began to drop more quickly than expected. The walk began at 5:56 p.m. Eastern Time, and the spacewalkers re-closed the airlock hatch 14 minutes later.
NASA flight controller John Curry ordered a "stand-down" at 7:14 p.m. Eastern time, saying the earliest the walk could be rescheduled was June 29.
It was the latest in a succession of breakdowns to afflict the station since space shuttle flights -- the station's primary source of resupply -- were halted by the Columbia disaster last year.
Since then, crewmen have jury-rigged and improvised to keep the station functioning properly. The last spacewalk in February was cut short after 21/2 hours when one of the Russian spacesuit helmets fogged up because of a cooling system problem. Despite that, Padalka and Fincke were using Russian suits yesterday because of cooling system malfunctions in two U.S. space suits.
Earlier this week, Michael Suffredini, NASA's manager for international space station integration and operations, said that although the U.S. spacesuits were unusable, "we have quite a bit of robustness on the Orlan [Russian spacesuit] side."
"The way we have [handled this] is to make sure we have plenty of Orlan resources on board," he added.
Yesterday's spacewalk was to have lasted six hours, with the crewmen aiming to replace a malfunctioning circuit breaker that had shut down one of the four "control moment gyroscopes," which keep the station oriented in space. An earlier problem with another gyroscope has left the station with only two gyroscopes working, the minimum needed.
The walk was to have involved two 45-minute traverses across the Russian side of the station, made necessary because the spacewalkers were wearing Russian suits and had to use the Russian airlock to exit and reenter the station.
The faulty circuit breaker is in a box mounted on the U.S. side of the station, which meant that the spacewalkers risked losing communications at points when their suit radios could not transmit to the Russian side. Controllers devised hand signals to cope with this problem and set up an "outpost" where the two crewmen could rendezvous to regain radio reception.
For Padalka, 45, the space station commander and a colonel in the Russian air force, the brief excursion was his spacewalk. It was the first for science officer Fincke, 37, a U.S. Air Force lieutenant colonel.
Once out of the airlock, Fincke, speaking in Russian, was reading off oxygen bottle and suit pressures to flight directors at the Russian Space Center in Korolev, when mission control interrupted.
"Gennady?" the controller said to Padalka. "You need to return. Something is not right. The pressure in Michael's prime [oxygen] bottle is falling. So close the hatch."
That brought the spacewalk to an end, the latest in a succession of misfortunes that have plagued the station. Russia's Soyuz transports and Progress cargo spacecraft have been ferrying crews and supplies to the orbiting laboratory, but they have only a fraction of the capacity of the workhorse shuttle, which can carry tons of equipment.
The space station lost one gyroscope two years ago to a bearing failure. Although NASA has a replacement available, only the shuttle can fly it up because it is four feet in diameter and weighs 600 pounds -- too large to fit inside the Progress. A second gyro had "spikes" in its performance, but has since settled down.
Other problems included a mysterious "rattling noise" that appeared to come from a fan in the Russian sleeping quarters and malfunctions in toxic substance detectors and an oxygen-producing unit.
For these and other breakdowns, mission managers and astronauts have devised "workarounds" and emergency repairs that have thus far proved effective. In one improvisation, ground crew engineers bought a tool called a bearing puller at an auto parts store and sent to the station so astronauts could repair a balky treadmill rather than wait for a bulky spare part.
Some shortcomings have not, however, yielded to easy fixes, and instead have led to some dubious "firsts" that, before Columbia, were contrary to NASA policy.
The February spacewalk was the first in which both of the station crewmen planned to work outside without a third person inside to monitor instruments and handle emergencies. Because of the resupply limitations, the station can only support two people at a time.
Suffredini said the decision to do the February spacewalk was "fortuitous," however, because planners working on yesterday's walk -- NASA's second two-person event -- already knew how to operate without an inside person.
Instead, they could focus on the latest "first" -- using Russian spacesuits to work on the U.S. side of the station, a challenge forced on the astronauts because of the failures of the U.S. suits. The station has only one working U.S. suit and no way to repair the damaged ones.