Manned Maneuvering Unit (MMU)

The Manned Maneuvering Unit (MMU) on display at the National Air and Space Museum's Udvar-Hazy Center was used on three space shuttle missions. Curator Valerie Neal explains how the MMU is a backpack propulsion device that enables an astronaut to fly free from the space shuttle and maneuver untethered for the purpose of retrieving objects, such as satellites, and returning them to the shuttle bay for servicing. Bruce McCandless was the first to test the MMU on February 7, 1984 during STS 41-B, and became the first human to fly free from a spacecraft and the first human satellite. Learn more about the MMU at