Friday, July 24, 2009

Long Spacewalk ahead for Endeavour Crew

Two astronauts aboard the space shuttle Endeavour will leave the airlock of the international space station this morning for a long and very busy spacewalk to install six new batteries and two video cameras on the orbital outpost.

Endeavour astronauts Chris Cassidy and Tom Marshburn (above, this morning), both making their second spacewalk, are set to switch their space suits to internal power at about 9:50 am EDT, to begin a 7 1/2-hours orbital walk in space.

The bulk of today's fourth spacewalk is aimed at the continued replacement of the final four batteries which help move the solar arrays attached to the Port 6 truss segment. The spacewalkers will also install two new Japanese video camera's on the Kibo module.

The cameras will assist in the docking of the unmanned Japanese cargo craft - the H-2 Transfer vehicle
. The first H-2 cargo craft is scheduled to launch from Japan bound for the station on September 10.

Due to Wednesday's shortened spacewalk due to Cassidy's carbon dioxide levels in his suit, Mission Control in southern Houston, will remind the pair to not get to excited about the spacewalk starting out so that their CO2 output is not to overwhelming for their suits CO2 scrubbers.

Wednesday's shortened work day allowed for the installation of only two of the four planned battery change outs. A total of six batteries, weighing 375 pounds each, will be changed out by the end of today's spacewalk.

On Thursday, the space station control room told Cassidy and Marshburn, "that it's important that they don't go out really excited and really fast like you normally would on your first spacewalk," space station Flight Director Holly Ridings stated last night. "They understand they need to take it slow at the beginning and let the LIOH (lithium hydroxide) can do its thing and then it will work efficiently for the duration."

Each spacesuit is like a mini spacecraft, and it supports oxygen, water and the measures to clean the small 10.2 PSI atmosphere in the space suit for the astronaut.

The crews of both the space station and Endeavour were awoken at 5:03 am EDT, this morning to the music of Wish You Were Here, by Pink Floyd, for lead spacewalker David Wolf. Wolf is sitting out this spacewalk having performed in the first three of the five planned from this STS-127 mission.

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