English: S90-30522 - STS-31 Mission Specialist (MS) Bruce McCandless II (left), wearing an extravehicular mobility unit (EMU), maneuvers his way around a mockup of the remote manipulator system (RMS) end effector during an underwater simulation in JSC's Weightless Environment Training Facility (WETF) Bldg 29 pool. The end effector is attached to a grapple fixture on the Hubble Space Telescope (HST) mockup. As McCandless performs contingency extravehicular activity (EVA) procedures, fellow crewmember MS Kathryn D. Sullivan, in EMU, works on the opposite side of the HST mockup, and SCUBA-equipped divers monitor the activity. Though no EVA is planned for STS-31, the two crewmembers train for contingencies that would necessitate leaving the shirt sleeve environment of Discovery's, Orbiter Vehicle (OV) 103's, crew cabin and performing chores with the HST payload or related hardware in the payload bay (PLB).