S99-06191 (21 June 1999) --- Astronaut John M. Grunsfeld, mission specialist, wearing an underwater-adapted training version of the Shuttle extravehicular mobility unit (EMU), prepares to go below the water in the Neutral Buoyancy Laboratory (NBL). Grunsfeld and other astronauts assigned to STS-103 space walk duty are in training for EVA chores they will handle when they make the third servicing visit to the Earth-orbiting Hubble Space Telescope (HST) since its deployment in April of 1990.
