ISS Crew to Toss Space Junk on Spacewalk

Astronauts living aboard the International Space Station (ISS) will take a trip outside tomorrow, but not to catch some rays.

The station's three-man Expedition 15 crew will toss more than 1,600 pounds (731 kilograms) of unneeded equipment toward Earth, perform some repairs and other clean up work during a Monday spacewalk to help make way for future expansion of the orbital laboratory.

"We know the crew's ready," said Daryl Schuck, NASA's lead extravehicular activity (EVA) officer for Expedition 15, during a recent press conference at NASA's Johnson Space Center in Houston, Texas. "We've got confidence in our approach to this and confidence in our crew."

Clayton Anderson, a NASA astronaut and ISS flight engineer, will lead the scrap-tossing spacewalk with the help of cosmonaut Expedition 15 commander Fyodor Yurchikhin. Flight engineer Oleg Kotov will provide support from inside the station by controlling the robotic arm, Canadarm2, to shuttle the astronauts around during their planned 6.5-hour EVA.

Prior to their leaving the airlock, however, the space station will swing around to make sure the new space junk doesn't come back to haunt the orbital laboratory. The spacewalk is set to begin from the station?s U.S. Quest airlock at 6:30 a.m. EDT (1030 GMT), marking the first career EVA for Anderson and the third for Yurchikhin.

Garbage toss

Anderson's biggest task, literally and objectively, will be to jettison a 1,400-pound (635-kilogram) old container of ammonia coolant, also known as an Early Ammonia Servicer (EAS). The astronaut will also toss a 212-pound (96-kilogram) video stanchion support assembly, or VSSA.

"Basically, it holds a camera," Bob Dempsey, NASA?s lead Expedition 15 flight director, said of the VSSA. The massive ammonia tank's purpose, he added, was to serve as backup coolant reservoir in case there were any leaks in the station's initial thermal control system.

"We do not need the ammonia, and the container has reached the end of its structural lifetime," he said of the agency's rationale to rid of the EAS.

While Kotov controls Canadarm2 from inside, Yurchikhin will unbolt the devices attached to the station. One by one, Anderson will then hold tightly to each object as the robotic arm slowly swings him away from the ISS to toss them away at about 1 mph (1.6 kph).

"He'll get it moving, then give it a final push with the arms," Schuck said. Cameras will monitor the toss to make sure it leaves the area at an acceptable direction and velocity.

NASA officials said each object will be tracked for roughly a year, at which point they'll mostly burn up the Earth's atmosphere?except for sizeable chunks of the ammonia tank.

"This is the first time we've ever done a jettison quite like this on the space station," Dempsey said, adding that while the agency doesn't know where the pieces will land, they should plunge into the ocean and not into satellites in orbit.

'Home improvement'

As the crew completes high-priority junk-tossing tasks, they will clean, repair and replace equipment on the ISS.

Yurchikhin will replace a failed circuit breaker, or remote power controller module (RPCM), while Anderson reconfigures a power supply.

In preparation for the major relocation of a piece of ISS hardware in September, Yurchikhin and Anderson will also carefully remove grit from one of the Unity module's common berthing mechanisms (CBM)?a silicon ring used to ensure an airtight seal with other station components.

When the EVA is complete, Anderson and Yurchikhin will rejoin Kotov inside the station. Controllers will then boost the ISS to a higher orbit in preparation for docking with Endeavour in August, as well as to avoid dangerous encounters with the ejected objects.

By the time it's over, Schuck said, "the crew will have jettisoned two items, cleaned a seal and changed out an RCPM. We'll be watching closely on the progress of the EVA from the ground."

NASA will broadcast Monday?s spacewalk outside the International Space Station live on NASA TV beginning at 6:00 a.m. EDT (1000 GMT). Click here for SPACE.com's live spacewalk updates and NASA TV feed.

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