Astronaut John M. Grunsfeld, mission specialist, wearing an underwater-adapted training version of the Shuttle extravehicular mobility unit (EMU), signals 'all's well' prior to going into 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 1990.