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The National Aeronautics and Space Administration (NASA) has accomplished a “return to extravehicular activity (EVA)” on the Space Transportation System 37 (STS-37) mission that flew in April 1991. This first U.S. EVA in almost 6 years included both an unscheduled EVA on mission day 3 and a scheduled EVA on mission day 4. The unscheduled EVA occurred when the high-gain antenna on the Compton Gamma Ray Observatory (GRO) would not deploy when commanded from the ground. Mission specialists Jerry Ross and Jay Apt quickly donned their space suits, went into the Shuttle cargo bay for EVA, and freed the jammed antenna, saving the $617 million scientific spacecraft. During the scheduled EVA, crewmembers Ross and Apt successfully completed the Space Station Freedom (SSF) EVA Development Flight Experiment (EDFE). EDFE evaluated three classes of equipment planned for SSF: Crew and Equipment Translation Aids (CETA), Crew Loads Instrumented Pallet (CLIP), and EVA Translation Evaluation (ETE).

Effective extravehicular-activity (EVA) operations depend upon having the proper tools from simple wrenches to smart powered socket drives to powered adjustable foot restraints. The Space Shuttle carries a standard toolkit in the cargo bay for emergencies. Many special tools have been developed for the recent satellite repair missions; i.e., Solar Max, Westar/Palapa, and Leasat. Many more are being developed to maintain the Hubble Space Telescope on orbit for 15 years. The EVA tools developed and used in space to date are summarized and some of the new tools now in development are described herein. Finally, the requirements are given for several additional tools which may be needed in the future.

The manned maneuvering unit (MMU) is a self-contained backpack with all the necessary systems to enable the extravehicular activity (EVA) astronaut to fly free in space and reach work areas remote from the supporting spacecraft. An experimental MMU tested onboard the NASA Skylab Program orbital workshop established key piloting characteristics and capability base for future MMU systems. An operational MMU now exists for the Space Shuttle Program. This versatile mobility system has been flown on nine sorties and accumulated 10 hr and 22 min of flying time during three Space Shuttle missions. These Space Shuttle flights have demonstrated a capability for free space traverses up to 98 m (320 ft), cargo transfer, and tracking, docking, stabilizing, and orienting large satellites. These and additional MMU capabilities will benefit the Space Station and its onboard payloads.