Oct 28 2007
From The Space Library
Mission Specialist Scott E. Parazynski and Flight Engineer Daniel M. Tani undertook the second EVA of STS-120, disconnecting cables from the P6 Truss, to remove the P6 Truss from the Z1 truss. Tani and Parazynski made progress outfitting the new Harmony module, mating the power and data grapple fixture, and reconfiguring connectors on the S1 truss, in preparation for the later deployment of the radiator on S1. Tani also inspected the SARJ, collecting fine metal shavings on part of a wheel with solar panels attached to it. The discovery of the metal shavings enabled engineers to identify the source of friction that had caused the wheel to begin slowing down in September. Engineers had designed the wheel to spin freely so that the solar panels pointed toward the Sun; the panels generated electricity to operate the ISS’s computers, oxygenproducing machine, and other systems. Tani reported that, in addition to collecting the metal shavings, he had observed that parts of the wheel’s surface appeared discolored, a possible sign of corrosion. To prevent further damage to the wheel, engineers stopped it from spinning, thereby reducing the amount of electricity that the panels generated. The spacewalk lasted 6 hours and 33 minutes.
NASA, “NASAfacts; STS-120”; Traci Watson, “Damaged Component Could Thwart Space Station Plans,” USA Today, 29 October 2007; John Schwartz, “Astronauts Discover Damage to Space Station,” 29 October 2007.
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