STS051-06-023 (16 Sept 1993) --- Astronauts James H. Newman (in bay) and Carl E. Walz, mission specialists, practice space walking techniques and evaluate tools to be used on the first Hubble Space Telescope (HST) servicing mission scheduled for later this year. Walz rehearses using the Power Ratchet Tool (PRT), one of several special pieces of gear to be put to duty during the scheduled five periods of extravehicular activity (EVA) on the STS-61 mission.