Written by Derek Kessler on
Friday, 01 February 2008
Astronauts Daniel Tani and Peggy Whitson ventured outside the International Space Station to replace a dead motor used to control the station's solar array's angle towards the sun. They spent seven and a half hours outside the orbital outpost working to restore the station's power systems to their intended output. The crippled motor had prevented them from angling the arrays for optimal sunlight reception.
In the past few months the ISS has been hit by dual power system problems. During the space shuttle Discovery's visit to the station in October they discovered that a large joint used to rotate an entire array was grinding. Until a repair course could be determined, NASA elected to lock the array where it was to prevent further damage.
And then in early December another motor on the array (controlling a different axis of rotation) failed, dropping the possible electical generation to below that needed to power the new modules soon to be delivered to the station. Tani and Whitson replaced that motor today - it was about the size of a trashcan.
The two had to be careful with the repair, as they were working close to the solar arrays which had close to 160 volts running through them. In order to reduce the chances of shock or electrical arcs, they had to work in 33-minute shifts while the ISS was in the Earth's shadow.
Mission planners believed that because of the timing and complexity of the replacement they would have to wait to send up a specialized and trained shuttle-based repair team, though Tani and Whitson proved capable of performing the repair themselves. This was the last scheduled spacewalk for the Expedition 16 crew.
Astronauts Daniel Tani and Peggy Whitson ventured outside the International Space Station to replace a dead motor used to control the station's solar array's angle towards the sun. They spent seven and a half hours outside the orbital outpost working to restore the station's power systems to their intended output. The crippled motor had prevented them from angling the arrays for optimal sunlight reception.
