Live in orbit: "Robos" wrap up spacewalk preps

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Crane operators aboard linked Discovery and the International Space Station just finished a 5 1/2-hour effort to convert the shuttle's heat-shield inspection boom into a makeshift scaffold for Saturday's spacewalking solar wing repair job.

Working inside the U.S. Destiny science laboratory, Dan Tani and Stephanie Wilson moved the station's 57.5-foot robot arm from a work site near the far left end of the outpost's central truss to another closer to the cargo bay of Discovery.














Perched atop a Canadian-built rail cart known as the Mobile Transporter, or MT, the station's crane crept 97 feet along tracks on the station's central truss, traveling at a speed of about five feet per minute.














Tani and Wilson then used "The Big Arm" to snatch the inspection boom from the starboard sill of Discovery's cargo bay.














The station crane operators hoisted the boom up and then maneuvered it into position above the shuttle's cargo bay.














Enter the shuttle arm operators. Working on the flight deck of Discovery, pilot George Zamka and commander Pam Melroy limbered up the shuttle's 50-foot arm and began cautiously moving it toward the boom.














Then they deftly grappled it.














Both the shuttle and station arms simultaneously held the boom until Tani and Wilson let it loose, carefully backing the "Big Arm" away from it.














Then they reversed course, moving the rail cart and the station arm back out to the work site near the far left end of the station's central truss.














The Canadian-built inspection boom will serve as a work platform for spacewalker Scott Parazynski when he attempts to make solar wing repairs on Saturday.

The lengthy operation today was aimed at preparing the boom for the spacewalk and maintaining a power stream to its laser sensors and camera, which still must be used to inspect the shuttle's heat shield before atmospheric reentry next week.

Tani and Wilson will grapple the boom with the station's arm an hour before the 6:28 a.m. EDT Saturday start of the spacewalk, disconnecting it from its shuttle orbiter power source. Engineers want to limit the amount of time it is without power so its sensors don't freeze and fail, rendering them useless for a now-standard shuttle heat-shield check prior to atmospheric reentry.

The spacewalk is expected to last six hours and 40 minutes.

The boom will be without power for about eight hours. Engineers are confident the sensors will survive without power in an environment where temperatures swing between 250 degrees Fahrenheit and Minus 250 degrees Fahrenheit. But there is no guarantee.