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The sign accompanying the AMU. It reads

AMU: Astronaut Maneuvering Unit

This AMU was created to allow USAF astronauts to leave their spacecraft for inspection, repair, assembly, and cold-war sabotage!

Invented in 1960 for the USAF by Bell rocket-propulsion engineer Wendell F. Moore, he nicknamed the AMU the "space belt".

The AMU was powered by bursts of nitrogen gas. Actuators on top and below the reaction-control units allowed the astronaut to precisely control movement forward and back, up and down, and side to side.

This AMU was used by Gene Cernan in training for his EVA aboard Gemini 9, March 1966.

Cernan began his EVA, which was to include flight with an AMU rocket pack but the Gemini suit couldn't handle the head load of his exertions. His faceplate fogged up, forcing him to blindly grope back into the Gemini. In two hours he had lost 10 pounds!

He later described his EVA as "... the space walk from hell."

Actually, the Gemini AMU was powered by the decomposition of 90% hydrogen peroxide. The resulting hot gas provided the unit's thrust, and to protect the astronaut from these hot plumes, the Gemini G4C suit was modified to include an outer layer of woven Chromel-R metal cloth over the legs. Nitrogen was used to pressurize the AMU's peroxide tanks, but was not used as a propellant gas (although I'm uncertain as to how this particular training unit operated).

The AMU was not tested during Project Gemini, but a similar unit was flown and tested on the Skylab missions. Modified for use inside the Orbital Work Shop, the renamed "Automatically Stabilized Maneuvering Unit" used nitrogen gas (so as to not contaminate the atmosphere).

An AMU derivative flew on the early Shuttle program as the manned maneuvering unit (MMU). The MMU also used nitrogen gas as its propellant.