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Wednesday, August 04, 2004

Third Spacewalk a Breeze for Space Station Crew

The crew of the International Space Station (ISS) flawlessly completed a spacewalk Tuesday morning, preparing their orbital home for a new cargo ship and retrieving experiments attached to its hull.

ISS Expedition 9 commander Gennady Padalka and NASA ISS Science Officer Michael Fincke are safely back inside the space station after a 4.5-hour spacewalk that found them consistently ahead of schedule and so eager to work that ground controllers repeatedly urged them to take breaks and enjoys the scenery.

“It’s a great view,” Fincke said during a rest early in the activity as he watched the sun rise during one of the spacecraft's 90-minute orbit of the planet.

The spacewalk was the third extravehicular activity (EVA) for the Expedition 9 crew and began when Padalka and Fincke opened the outer hatch of the station’s Pirs Docking Compartment at 2:58 a.m. EDT (0658 GMT) Tuesday morning. By the spacewalk’s end at 7:28 a.m. EDT (1128 GMT), the astronauts had completed all of their EVA tasks.

Preparing for ‘Jules Verne’

Expedition 9’s primary task during the spacewalk was to prepare a docking port on the aft end of the station’s Zvezda Service Module to receive an unpiloted European supply vehicle expected to make its first delivery in the fall of 2005.

The cargo-carrying Autonomous Transfer Vehicle (ATV), named Jules Verne by its builders, is an unmanned spacecraft developed by the European Space Agency (ESA). It carries three times the cargo capacity of Russia’s unmanned Progress ships, and may also be used to move the ISS if needed.

It took the Expedition 9 crew about 30 minutes from exiting the space station to reach their Zvezda worksite, but once the astronauts arrived, they were all business.

Padalka and Fincke removed six obsolete laser reflectors used for docking, replacing four of them with more modern versions. The crew also installed two antennas - to allow the Jules Verne ATV to communicate with the space station - and removed a cable from a faulty television camera that will be retrieved in a later spacewalk.

The astronauts also replaced a series of space exposure experiments, including a folding replaceable cassette container filled with materials and a Kromka experiment that measured contamination caused by the station’s thrusters.

“I did not work much,” said an energetic Padalka during the spacewalk. “I’m not tired.”

Drifting in space

Despite their busy schedule, Padalka and Fincke snagged some 40 minutes of down time while outside the space station when mission controllers reoriented the station using its Russian thrusters.

The reorientation was required primarily to counteract the effect of the Expedition 9 crew, NASA spacewalk commentators said.

When the Expedition 9 crew first ventured out to the aft of Zvezda, U.S. station handlers put the ISS under U.S. momentum gyroscope control to prevent Russian thrusters on the module from firing while crewmembers were near.

But the heavy work activity on Zvezda’s aft by Padalka and Fincke increased the momentum load on the gyroscopes and the station began to drift slightly off course. The drift led ground controllers to institute power conservation procedures that temporarily cut off primary S-band communications with the Expedition 9 crew, though a backup system reestablished contact.

NASA officials said Russian and U.S. station controllers had anticipated the drift, but concluded it posed no danger to the crew or station. It was easily cancelled out at about 5:15 a.m. EDT (0915 GMT), when Russian thrusters were fired while Padalka and Fincke were at a safe distance from Zvezda’s aft.

By 6:00 a.m. EDT (1000 GMT),the spacewalkers resumed their work.

One more to go

Padalka and Fincke still have one last spacewalk to perform before they turn the ISS over to new tenants in October. Some of those activities will also be ATV-related, NASA officials said. Tuesday’s spacewalk was the 55th EVA made to support space station and the 12th staged from the Pirs compartment. The spacewalk marks Padalka’s fifth career spacewalk and the third for Fincke. The three Expedition 9 spacewalks to date total of more than 10 hours of EVA work for the astronauts.


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