Risky Spacewalk Underway

Determined to do better than last week, the international space station's two astronauts ventured back outside Wednesday on an unusually risky spacewalk to replace a bad circuit board.

American spaceman Mike Fincke and his Russian partner Gennady Padalka were so eager to get the repair work done that they popped open the hatch almost a half-hour early.

The two spacewalkers were running about eight minutes ahead of schedule and communications through Russian antennas at the far end of the station remained clear, reports CBS News Space Consultant Bill Harwood. They are in the process of gaining access to the faulty circuit breaker they plan to replace to restore one of the station's main gyroscopes to operation.

Last Thursday, their first attempt at the job was aborted just 14 minutes after they opened the hatch. 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.

This time, Fincke and Padalka verified that the switches on both of their suits were in the right setting. Nevertheless, flight controllers kept asking the men for oxygen-pressure updates.

Mission Control radioed up other precautions: "Make sure your hands don't get tired. And again: "We have plenty of time. Move slowly."

"It was good to get that little practice run in there last week," Mission Control radioed prior to the spacewalk. "I've got a feeling today's going to go great."

"We feel the same way," Fincke replied.

NASA was anxious to get the circuit board replaced to restore power to one of the gyroscopes that keep the 225-mile-high outpost steady and pointed in the right direction. The circuit board conked out in April, leaving the space station with just two good gyroscopes, the bare minimum.

The spacewalk was considered riskier than most, and not just because the men were using Russian suits not intended for this type of hand-intensive, U.S. repair work.

The space station is down to just two crew members, instead of three, because of the grounding of the shuttle fleet since the Columbia disaster. As a result, no one was left inside to watch over the station during the spacewalk — a situation NASA never tolerated until this year.

A cooling failure in the space station's American spacesuits a month ago forced the switch to the stiffer, more-pressurized Russian suits.

Using the Russian suits meant an exit from the Russian hatch — 80 feet to 100 feet from the broken circuit breaker — and an excursion over treacherous terrain, including antennas and jagged edges that could tear a spacesuit. The 50-foot 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.

At one point, the cables were so numerous and dense that it sounded as though the spacemen were making their way through a jungle.

NASA expected the work to take longer and be more fatiguing because of the stiffer gloves and suits and because of the extra distance. Going out the U.S. hatch would have entailed a 30-foot hike.

The distance was so great that communication blackouts were anticipated; the spacemen planned to resort to hand signals, if necessary.

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 50 minutes into the spacewalk and appeared to be seamless. It was obvious to anyone listening in; the conversation abruptly switched from Russian to English.