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Gyro working again after spacewalk

One week after an abortive spacewalk, the international space station’s two astronauts ventured back outside and made badly needed repairs to the station's stabilizing system.
Russian cosmonaut Gennady Padalka makes repairs on the exterior of the international space station Wednesday.
Russian cosmonaut Gennady Padalka makes repairs on the exterior of the international space station Wednesday.NASA TV
/ Source: The Associated Press

The two men aboard the international space station pulled off a riskier than usual spacewalk and successfully plugged in a new circuit breaker, drawing cheers and sighs of relief.

As soon as American Mike Fincke and Russian Gennady Padalka learned their second shot at the spacewalking repair had paid off, cries of “hurray!” and “great!” erupted 225 miles (360 kilometers) up. The feeling was mutual down below.

“Great job, you guys,” Mission Control radioed.

“We’re glad to be able to be of service,” Fincke said.

The triumph was especially sweet following last week’s failed attempt.

It was a long and potentially dangerous haul to the work site — and back to the hatch after the repairs were made.

Fincke and Padalka had to cross nearly 100 feet (30 meters) to get to the bad circuit breaker — a grueling distance for spacewalkers over difficult terrain. Then they had to pry off the cover for the row of circuit breakers; it was stiff and incredibly hard to move.

Despite the hurdles, the two stayed ahead of schedule the entire time. Flight controllers kept urging them to take their time and be careful; the warnings came more frequently as the men returned from the work site.

Less than six hours after venturing out, the men were safely back inside. “We had a really nice time out there and I think we helped out the space station,” Fincke told Mission Control as he heated up a celebratory dinner.

Last week's glitch
Last Thursday, Fincke and Padalka barely made it out the hatch when their spacewalk was aborted, just 14 minutes after it began. An oxygen-flow switch on Fincke’s suit did not lock into the proper position and oxygen gushed out of his tank, prompting flight controllers to order the spacewalkers back inside.

NASA was anxious to replace the circuit breaker to restore power to one of the gyroscopes that keep the outpost steady and pointed in the right direction. The circuit breaker stopped working in April, leaving the space station with just two good gyroscopes, the bare minimum.

Thanks to the new circuit breaker, ground controllers were able Thursday to slowly and methodically nudge the third gyroscope, or spinning wheel, back into operation. A fourth gyroscope has been broken for two years but cannot be replaced until space shuttle flights resume.

Risky operation
The spacewalk was riskier than most, in large part because of the ramifications from last year’s Columbia accident.

No one was inside to monitor systems during the spacewalk, a situation NASA never tolerated until this year. But with the crew size reduced from three to two because of the grounding of the shuttle fleet, flight controllers had to serve as the so-called third crew member.

Fincke and Padalka also had to use Russian suits not intended for this type of hand-intensive, U.S. repair work. A cooling failure in the space station’s American spacesuits a month ago forced the switch to the stiffer, more-pressurized Russian suits.

After floating through the Russian hatch Wednesday, Fincke and Padalka cranked open a boom to traverse the station and made it to the work site all the way over on the U.S. side without incident about 1½ hours later.

Within minutes, they removed the old circuit breaker — a rectangular box about the size of a dictionary — and pushed in the spare. Flight controllers immediately ran a series of electrical tests and confirmed that the swap was good.

Longer excursion
Using the Russian suits meant an exit from the much more distant Russian hatch — 80 feet to 100 feet (25 to 30 meters) from the broken circuit breaker — and an excursion over treacherous terrain, including antennas and jagged edges that could tear a spacesuit. The 50-foot (15-meter) extension boom helped close the gap, but the crew still had a considerable amount of hand-over-hand walking to do and an assortment of safety tethers — both Russian and American — to hook and unhook.

The distance was so great that communication blackouts were anticipated; Fincke and Padalka planned to resort to hand signals, if necessary. But the radio links held up fine and the spacewalkers even pulled off a few maintenance chores.

Another first on this spacewalk: Prime responsibility for the job was divided between the two Mission Controls, in Moscow and Houston, depending on what side of the station the astronauts were on at any given moment.

The first shift in control came an hour into the spacewalk and appeared to be seamless. It was obvious to anyone listening in; the conversation abruptly switched from Russian to English. Everything reverted back to Russian, near the end.