Manned Maneuvering Unit: Encyclopedia II - Manned Maneuvering Unit - History

Manned Maneuvering Unit - History

The MMU was used on three Shuttle missions in 1984. It was first tested on February 7 during mission STS-41-B by astronauts Bruce McCandless and Robert L. Stewart. Two months later during mission STS-41-C, astronauts James van Hoften and George Nelson used the MMU to capture the Solar Maximum mission satellite and to bring it into the orbiter's payload bay for repairs and servicing. Their work increased the lifespan of the satellite.

The final MMU mission was STS-51-A, which flew in November of 1984. The propulsion unit was used to retrieve two communication satellites, Westar VI and Palapa B2, that did not reach their proper orbits because of faulty propulsion modules. Astronauts Joseph P. Allen and Dale Gardner captured the two satellites and brought them into the Orbiter payload bay for stowage and return to Earth.

After the Space Shuttle Challenger disaster, the MMU was judged too risky. NASA also discontinued using Shuttle for commercial satellite contracts, and the military also discontinued use of Shuttle, eliminating the main potential uses. Although envisioned as a natural aid for constructing the International Space Station, with its retirement NASA developed different tethered spacewalk approaches. The MMU gas ejecta would be too damaging for the only other ongoing task, upkeep of the Hubble Space Telescope.

Adapted from the Wikipedia article "History", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki