Astronaut Maneuvering Unit
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An astronaut propulsion unit (or astronaut maneuvering unit) is used to move an astronaut relative to the spaceship during a
spacewalk Extravehicular activity (EVA) is any activity done by an astronaut in outer space outside a spacecraft. In the absence of a breathable atmosphere of Earth, Earthlike atmosphere, the astronaut is completely reliant on a space suit for environmen ...
. The first astronaut propulsion unit was the Hand-Held Maneuvering Unit (HHMU) used on
Gemini 4 Gemini 4 (officially Gemini IV) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was the second crewed spaceflight in NASA's Project Gemini, occurring in June 1965. It was the tenth crewed American spaceflight (inc ...
.


Models


Hand-Held Maneuvering Unit

The Hand-Held Maneuvering Unit was the
EVA Eva or EVA may refer to: * Eva (name), a feminine given name Arts, entertainment, and media Fictional characters * Eva (Dynamite Entertainment), a comic book character by Dynamite Entertainment * Eva (''Devil May Cry''), Dante's mother in t ...
"zip" gun used by Ed White on the
Gemini 4 Gemini 4 (officially Gemini IV) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was the second crewed spaceflight in NASA's Project Gemini, occurring in June 1965. It was the tenth crewed American spaceflight (inc ...
mission in 1965. The hand-held gun held several pounds of nitrogen, and allowed limited movement around the
Gemini spacecraft Project Gemini () was NASA's second human spaceflight program. Conducted between projects Mercury and Apollo, Gemini started in 1961 and concluded in 1966. The Gemini spacecraft carried a two-astronaut crew. Ten Gemini crews and 16 individual ...
. It was also used by astronaut
Michael Collins Michael Collins or Mike Collins most commonly refers to: * Michael Collins (Irish leader) (1890–1922), Irish revolutionary leader, soldier, and politician * Michael Collins (astronaut) (1930–2021), American astronaut, member of Apollo 11 and Ge ...
on the
Gemini 10 Gemini 10 (officially Gemini X) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was a 1966 crewed spaceflight in NASA's Gemini program. It was the 8th crewed Gemini flight, the 16th crewed American flight, and t ...
mission in 1966.


USAF Astronaut Maneuvering Unit

The United States Air Force (USAF) Astronaut Maneuvering Unit (AMU) was designed by the
U.S. Air Force The United States Air Force (USAF) is the air service branch of the United States Armed Forces, and is one of the eight uniformed services of the United States. Originally created on 1 August 1907, as a part of the United States Army Sign ...
, which was planning to use the Gemini spacecraft as part of the
Manned Orbiting Laboratory The Manned Orbiting Laboratory (MOL) was part of the United States Air Force (USAF) human spaceflight program in the 1960s. The project was developed from early USAF concepts of crewed space stations as reconnaissance satellites, and was a s ...
(MOL). The AMU was a backpack using
hydrogen peroxide Hydrogen peroxide is a chemical compound with the formula . In its pure form, it is a very pale blue liquid that is slightly more viscous than water. It is used as an oxidizer, bleaching agent, and antiseptic, usually as a dilute solution (3%†...
as the fuel. The total delta-v capability of the AMU was about 250 feet per second (76.2 meters per second), roughly three times that of the MMU. The astronaut would strap on the AMU like a backpack, and maneuver around using two hand controllers like that of the later MMU. Because of the fuel, which came out as a hot gas, the astronaut's suit had to be modified with the addition of woven metal "pants" made of Chromel-R metal cloth. The AMU was carried aboard the
Gemini 9 Gemini 9A (officially Gemini IX-A) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was a 1966 crewed spaceflight in NASA's Gemini program. It was the seventh crewed Gemini flight, the 13th crewed American flight ...
mission, but was not tested because the astronaut,
Eugene Cernan Eugene Andrew Cernan (; March 14, 1934 â€“ January 16, 2017) was an American astronaut, naval aviator, electrical engineer, aeronautical engineer, and fighter pilot. During the Apollo 17 mission, Cernan became the eleventh human being to ...
, had difficulty maneuvering from the Gemini cabin to the AMU storage place, at the back of the spacecraft, and overheated, causing his helmet faceplate to fog up. The AMU was also meant to be launched and flown on-board
Gemini 12 Gemini 12 (officially Gemini XII) With Gemini IV, NASA changed to Roman numerals for Gemini mission designations. was a 1966 crewed spaceflight in NASA's Project Gemini. It was the 10th and final crewed Gemini flight ( Gemini 1 and Gemini 2 wer ...
, and to fly untethered from the Gemini spacecraft, but was scrubbed two months before the mission.
NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...
chief astronaut
Deke Slayton Donald Kent "Deke" Slayton (March 1, 1924 – June 13, 1993) was a United States Air Force pilot, aeronautical engineer, and test pilot who was selected as one of the original NASA Mercury Seven astronauts. He went on to become NASA's first ...
later speculated in his autobiography that the AMU may have been developed for the MOL program because the Air Force "thought they might have the chance to inspect somebody else's satellites."


Automatically Stabilized Maneuvering Unit (ASMU)

In 1973, the
Automatically Stabilized Maneuvering Unit Automatic may refer to: Music Bands * Automatic (band), Australian rock band * Automatic (American band), American rock band * The Automatic, a Welsh alternative rock band Albums * ''Automatic'' (Jack Bruce album), a 1983 electronic rock ...
(ASMU) was test-flown aboard
Skylab Skylab was the first United States space station, launched by NASA, occupied for about 24 weeks between May 1973 and February 1974. It was operated by three separate three-astronaut crews: Skylab 2, Skylab 3, and Skylab 4. Major operations in ...
during the
Skylab 3 Skylab 3 (also SL-3 and SLM-2) was the second crewed mission to the first American space station, Skylab. The mission began on July 28, 1973, with the launch of NASA astronauts Alan Bean, Owen Garriott, and Jack Lousma in the Apollo command ...
and 4 missions. Tested inside of the orbiting laboratory, it used nitrogen gas allowing both unsuited and suited testing of the unit. The Skylab AMU was the closest to the Shuttle MMU, but was not used outside the spacecraft because the EVAs were conducted with the astronauts attached to life support umbilicals, and to prevent damage to the delicate solar arrays on the
Apollo Telescope Mount The Apollo Telescope Mount, or ATM, was a crewed solar observatory that was a part of Skylab, the first American space station. It could observe the Sun in wavelengths ranging from soft X-rays, ultra-violet, and visible light. The ATM was man ...
.


Foot Controlled Maneuvering Unit (FCMU)

The
Foot Controlled Maneuvering Unit The foot ( : feet) is an anatomical structure found in many vertebrates. It is the terminal portion of a limb which bears weight and allows locomotion. In many animals with feet, the foot is a separate organ at the terminal part of the leg made ...
was tested within Skylab. The purpose of it was to free the astronaut's hands. It was propelled by cold, high-pressured
nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
gas located in a tank on the back. It was tested both suited and unsuited.


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.


Soviet SPK

The former
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...
also used a cosmonaut propulsion system on flights to the space station
Mir ''Mir'' (russian: Мир, ; ) was a space station that operated in low Earth orbit from 1986 to 2001, operated by the Soviet Union and later by Russia. ''Mir'' was the first modular space station and was assembled in orbit from 1986 to&n ...
. The SPK (or UMK, UPMK) was larger than the Space Shuttle MMU, contained oxygen instead of nitrogen and was attached to a safety tether. Despite the tether, the SPK allowed the cosmonaut, wearing the self-contained Orlan spacesuit, to "fly around" the orbiting complex, allowing access to areas nearly impossible to access otherwise. Though tested on Mir in 1990, the cosmonauts preferred using the ''Strela'' crane (equivalent to the
Mobile Servicing System The Mobile Servicing System (MSS), is a robotic system on board the International Space Station (ISS). Launched to the ISS in 2001, it plays a key role in station assembly and maintenance; it moves equipment and supplies around the station, supp ...
). The SPK, which was left attached to the outside to the
Kvant-2 Kvant-2 (russian: Квант-2; English: Quantum-II/2) (77KSD, TsM-D, 11F77D) was the third module and second major addition to the Mir space station. Its primary purpose was to deliver new science experiments, better life support systems, and an ...
module, was destroyed when Mir re-entered the atmosphere after decommissioning. The 21KS system is a completely new design for Orlan-DMA spacesuit not using a safety tether, but air jet engines. This system was similar to MMU. It was automatically stabilized, used 6 degrees of freedom, weighed less than 180 kg, had a delta-v of 30 m/s, practical speed of 1 m/s, and an emergency mode that allows for rotational acceleration of 8°/s^2.


SAFER

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 Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
, 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 bola-type lasso device ( astrorope) the drifting astronaut could throw to hook to the space station.


References


Further reading

*


External links


"More Favored than the Birds": The Manned Maneuvering Unit in Space

NASA Manned maneuvering unit: User's guide - 1978 (PDF document)

Assessment of the NASA Manned Maneuvering Unit - 1988 (PDF document)


{{Use American English, date=January 2014 Human spaceflight
propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...
1965 introductions Projects established in 1965