Space -shuttle Endeavour

In this image from NASA TV Astronaut Tom Marshburn is seen during a spacewalk on the international space station, Monday, July 27, 2009.

In this image obtained from NASA, astronaut Tom Marshburn begins work on installing video cameras during the Endeavour crew's fifth and final space walk of the shuttle Endeavour's mission to complete the International Space Station.The final spacewalk is expected to run about six and a half hours.

Astronaut Christopher Cassidy (centre) is watched by Tom Marshburn just after coming out of the air lock during the Endeavour crew's fourth space walk. Two astronauts will venture into open space again Monday on a fifth and final spacewalk of the shuttle Endeavour's mission to complete the International Space Station.

astronaut Christopher Cassidy is seen during the Endeavour crew's fourth space walk. Two astronauts will venture into open space again Monday on a fifth and final spacewalk of the shuttle Endeavour's mission to complete the International Space Station.

In this July 25, 2009 photo provided by NASA, the limb of Earth intersects one of two Soyuz spacecraft that are docked with the International Space Station.