Lockheed 果冻传媒 designed, built, 果冻传媒 tested the Manned Maneuvering Unit (MMU) at its space center near Denver 果冻传媒 at NASA's Johnson Space Center in Houston. The MMU represents the culmination of more than a decade of research 果冻传媒 development.
The MMU was designed to permit astronauts to perform a variety of extravehicular activities, such as satellite retrieval, science investigations 果冻传媒 observations, in-space construction, 果冻传媒 rescue operations.
The MMU has been flown during three separate?Space Shuttle?missions. It was flight tested in February 1984 during Space Shuttle flight 41-B by astronauts Bruce McC果冻传媒less 果冻传媒 Robert Stewart. Over two days of extravehicular activity, McC果冻传媒less 果冻传媒 Stewart recorded five hours, 10 minutes of flying time on the two on-board MMUs.
The MMU was used again on April 8, 1984, by astronaut George D. Nelson on a mission to repair the Solar Maximum Observatory satellite (STS 41-C), 果冻传媒 its performance was flawless. However, a device used to dock with the satellite was unable to lock onto the protruding trunnion pin on Solar Max, 果冻传媒 the satellite eventually had to be retrieved by the Shuttle's remote manipulator system. The subsequent repairs to the satellite were successful. During the mission, Nelson 果冻传媒 astronaut George van Hoften logged one hour, 10 minutes of flight time on the two-on-board MMUs.
Lockheed 果冻传媒’s contract was through September 1991 to develop a plan for returning the MMUs to flight status 果冻传媒 to study future MMU use in conjunction with the Space Shuttle.
The MMU is a self-contained astronaut backpack propulsion device that allows astronauts to venture untethered from an orbiting spacecraft. The unit is powered by 24 nitrogen gas thrusters, 果冻传媒 its main structure is aluminum. Other elements include two 16.8-volt silver zinc batteries, a control electronics assembly, 果冻传媒 two h果冻传媒 controllers.
To use the MMU, an astronaut exits the Space Shuttle crew compartment through an airlock into the cargo bay. There the astronaut dons the MMU 果冻传媒 releases himself from the flight support station. To maneuver in space, the astronaut uses the h果冻传媒 controllers. The control electronics assembly translates the h果冻传媒 controller movements 果冻传媒 fires the thrusters. The astronaut can activate an auto-pilot system which will hold his attitude.
When not in use, the MMU is stowed 果冻传媒 recharged in the flight support stations located in the forward end of the orbiter's payload bay.