Dec 10 2001
From The Space Library
Endeavour crew members Linda M. Godwin and Daniel M. Tani completed a 4-hour spacewalk to repair the rotating mechanisms on the solar arrays attached to the outside of the ISS. The solar-powered module provided electrical power for the space station’s communications, life-support, and steering systems, as well as for scientific experiments conducted aboard the ISS. However, flight-control personnel had found that the solar arrays were consuming more electrical power than expected. Project engineers attributed this to temperature-induced contraction and expansion in the bearings within the motors that rotated the solar arrays. Contraction and expansion was occurring because of the temperatures outside of the ISS, which ranged from 200ºF to 200º below 0ºF (93.3ºC to -128.9ºC), during each orbit of Earth. Therefore, Godwin and Tani were installing insulation around the motors in an effort to stop the bearings from undergoing contraction and expansion. (Mark Carreau, “Astronauts Make Breathtaking Repair Trip,” Houston Chronicle, 11 December 2001.)
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