Successful Shuttle Mission Marks NASA's Return to ISS Assembly

摘要

Nasa astronauts Piers Sellers and Michael Fossum completed three space-walks during the STS-121 mission, vital steps towards NASA's goal of finishing assembly of the international space station (ISS) and verifying the integrity of the Space Shuttle Discovery's heat shield for a safe return to Cape Canaveral. During the first spacewalk July 8, Sellers and Fossum spent most of their time determining the stability of Discovery's 30-meter robotic appendage to determine its stability for the delicate work that might one day be necessary to fix an orbiter's damaged heat shield.