STS109-E-5382 (6 March 2002) --- Astronaut John M. Grunsfeld, payload commander, waves at a crewmate inside Space Shuttle Columbia's crew cabin during a brief break in work on the Hubble Space Telescope (HST) in the cargo bay of the shuttle during the STS-109 mission's third space walk. The primary purpose of the extravehicular activity (EVA) of astronauts Grunsfeld and Richard M. Linnehan was to replace the Power Control Unit on the giant telescope. The image was recorded with a digital still camera by one of Grunsfeld's crew mates inside Columbia's cabin.