Astronaut Maneuvering Unit (AMU)

The Astronaut Maneuvering Unit (AMU) was essentially a jet pack meant to help astronauts move around while on spacewalks. Gemini 9A astronaut Gene Cernan was tasked with testing an AMU like this one during his spacewalk on June 5, 1966.

Cernan was the second American to complete a spacewalk. Nearly everything about the Gemini 9A mission and his spacewalk was new and unknown to him, to his crewmate Tom Stafford, and to NASA. The main purpose of the spacewalk was to test ways in which astronauts could maneuver in open space, including the AMU. There were 35 steps to go through before it was ready to fly, many near impossible in zero gravity while wearing a clumsy spacesuit and thick gloves. Trying to turn a lever or valve would send his body turning the opposite direction. Pulling on the telescoping arms was like “straightening wet spaghetti.”

When Cernan eventually got the AMU prepped and was strapped in to it, he took a break to assess. His breathing was so heavy that his visor had completely fogged over — he was using his nose to clear a small window. His normal heart rate had tripled. He had ripped apart the back seams on the inner layers of his suit and was now seriously sunburned. Using the line-of-site radio on the AMU left him with severely degraded communications with Stafford. For Cernan’s safety, it was decided that the AMU test flight should be scrapped, and he should return to the module.

After two hours and nine minutes, Cernan returned to the module with the rest of the day to relax before returning home. But first they jettisoned the unused, ten-million-dollar AMU because its explosive fuel package posed too much of a risk during reentry. The AMU was not tested on any other Gemini missions or used during the Apollo program.

Read more about Gene Cernan's spacewalk on the Bullock Museum's Medium channel.