Astronaut propulsion unit

[[File:STS-41-B EVA.jpg|thumb|left|180px|The MMU during a Shuttle flight.]]

[[File:STS-41-B EVA.jpg|thumb|left|180px|The MMU during a Shuttle flight.]]

{{main|Manned Maneuvering Unit}}

{{main|Manned Maneuvering Unit}}

The Manned Maneuvering Unit (MMU) is a propulsion backpack which was used by NASA astronauts on three space shuttle missions in 1984. The MMU allowed the astronauts to perform untethered EVA spacewalks at a distance from the shuttle. The MMU was used in practice to retrieve a pair of faulty communications satellites, Westar VI and Palapa B2. Following the third mission the unit was retired from use.

The Manned Maneuvering Unit (MMU) is a propulsion backpack which was used by NASA astronauts on three [[Space Shuttle|space shuttle]] missions in 1984. The MMU allowed the astronauts to perform untethered EVA spacewalks at a distance from the shuttle. The MMU was used in practice to retrieve a pair of faulty communications satellites, [[Westar]] VI and Palapa B2. Following the third mission the unit was retired from use.

===Soviet SPK===

===Soviet SPK===

===SAFER===

===SAFER===

{{main|Simplified Aid For EVA Rescue}}

{{main|Simplified Aid For EVA Rescue}}

The Simplified Aid For EVA Rescue (SAFER) is a smaller backpack propulsion system intended as a safety device during space walks. It contains 1.4 kg of gaseous [[nitrogen]], which provides much less delta-v capability than the MMU, roughly 10 feet per second (3 meters per second). However SAFER is less complex, less expensive and simpler to use than the MMU, and the limited delta-v is sufficient for the intended rescue-only task. Other Crew Self Rescue (CSR) devices of which prototypes have been developed include an inflatable pole, a telescoping pole, a bi-stem pole and a [[bolas|bola]]-type lasso device ([[astrorope]]) the drifting astronaut could throw to hook to the space station.

The [[Simplified Aid For EVA Rescue]] (SAFER) is a smaller backpack propulsion system intended as a safety device during space walks. It contains 1.4 kg of gaseous [[nitrogen]], which provides much less delta-v capability than the MMU, roughly 10 feet per second (3 meters per second). However SAFER is less complex, less expensive and simpler to use than the MMU, and the limited delta-v is sufficient for the intended rescue-only task. Other Crew Self Rescue (CSR) devices of which prototypes have been developed include an inflatable pole, a telescoping pole, a bi-stem pole and a [[bolas|bola]]-type lasso device ([[astrorope]]) the drifting astronaut could throw to hook to the space station.

==References==

==References==