NASA Spacewalkers Thwarted In Repair Efforts

HOUSTON – U.S. and Japanese astronauts Sunita Williams and Akihiko Hoshide struggled unsuccessfully to replace a failing Main Bus Switching Unit (MBSU) outside the International Space Station during an Aug. 30 spacewalk, the first NASA-chartered excursion in nearly 14 months. Though secured by just two bolts, the spacewalkers found it difficult to unscrew the fasteners holding the old device in place on the station’s long solar power truss. Once they did, they discovered small amounts of galling inside the bolt receptacles that prevented efforts to install and re-secure a new MBSU ...