STS109-E-5225 (4 March 2002) --- Astronaut John M. Grunsfeld, payload commander, signals readiness for the first the first of his assigned STS-109 space walks to perform work on the Hubble Space Telescope (HST). Astronauts Grunsfeld and Richard M. Linnehan moments later egressed the Space Shuttle Columbia's airlock, eventually replacing the giant telescope’s starboard solar array during a space walk that ended at 7:38 a.m. (CST) or 13:38 GMT March 4, 2002.