Endeavour mission STS-126 specialists Steve Bowen and Heide Stefanyshyn-Piper will this afternoon venture outside the International Space Station for the first of four planned spacewalks on this shuttle jaunt to the orbiting outpost.

Endeavour and resident ISS Expedition 18 crew members yesterday used a robotic arm to attach the Leonardo Multi-Purpose Logistics Module to the ISS - part of the station's expansion to accommodate a permanent crew of six.

Bowen and Piper should exit the ISS at 13:45 EST (18:45 GMT) for a six-and-a-half hour stint which will see them "replace a depleted nitrogen tank and a device used to help the flow of coolant from the truss, the backbone of the station" and "remove thermal covers from the Japanese Kibo module to inspect the berthing mechanism where the module's exposed facility will be installed during the STS-127 mission in 2009".

They'll also "start inspecting, cleaning and lubricating the starboard SARJ [solar alpha rotary joint] and begin replacing 11 of 12 trundle bearings".

Inside the station, meanwhile, STS-126 mission specialist Don Pettit and Expedition 18 flight engineer Sandra Magnus will "operate the station's robotic arm, and mission specialist Shane Kimbrough will be the intravehicular officer, or spacewalk coordinator".

Bowen and Piper spent last night on a "campout" in the station's Quest Airlock in order to "purge the nitrogen from their bodies before their planned exit from the station"

NASA has an STS-126 mission summary here (pdf) and the main mission section here. ®

Bootnote

Check out this nice snap released today of ISS crew member Greg Chamitoff working in the Destiny laboratory. Looks like a zero-grav version of the Reg Hardware office...

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