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{{Unreferenced|date=February 2009}}
[[Image:STS-118 EVA EMU Suit.jpg|thumb|270px|The Enhanced EMU Suit]]

The '''[[Space Shuttle]]/[[International Space Station]] Extravehicular Mobility Unit''' (EMU) is an independent anthropomorphic system that provides environmental protection, mobility, life support, and communications for a Shuttle or ISS crew member to perform [[extra-vehicular activity]] (EVA) in [[earth orbit]]. It is a two-piece semi-rigid suit and it is currently one of two [[space suit]]s used by crew members on the ISS, the other being the Russian [[Orlan space suit]].

==Suit components==
The suits are white to reflect heat and to stand out against to the blackness of space, the red stripes serve to differentiate astronauts.

[[Image:Emu spacesuit control module.jpg|right|thumb|240px| The EMU Display and Control Module (DCM)]]
The EMU, like the [[Apollo/Skylab A7L]] spacesuit, was a result of years of research and development. It consists of a [[Hard Upper Torso]] (HUT) assembly, a [[Primary Life Support System]] (PLSS) which incorporates the life support and electrical systems, arms, gloves, Apollo-style "bubble" helmet/Extravehicular Visor Assembly (EVVA), and a soft Lower Torso Assembly (LTA), incorporating the Body Seal Closure (BSC), waist bearing, brief, legs, and boots. Prior to donning the pressure garment, the crew member puts on a [[Maximum Absorbency Garment]] (MAG) [basically a modified "Depends" incontinence diaper] (Urine Collection Devices or UCDs are no longer used), possibly a Thermal Control Undergarment (long johns), and then the "[[Liquid Cooling and Ventilation Garment]]" (LCVG), that incorporates clear plastic tubing through which chilled liquid water flows for body temperature control, as well as ventilation tubes for waste gas removal.

Once the astronaut dons the LCVG, the astronaut then puts on the LTA, similar in nature to a firefighter putting on the pants and boots of a fire protection suit. The astronaut then floats into the airlock, dons the HUT, connects the LCVG umbilical to the umbilical in the HUT, and then the two parts of the suit are locked together using the Body Seal Closure. Once the suit is turned on and checked out, the astronaut then dons a "[[Snoopy]] cap," a brown and white fabric communications cap dating back to the [[Project Apollo|Apollo]] days that incorporates a pair of earphones and microphones, allowing the EVA astronaut to communicate with both the crew members in the Orbiter and ground controllers in [[Johnson Space Center|Houston]]. After donning the "Snoopy cap," the gloves and helmet are then locked on, pressurizing the suit. The suit's regulator and fans activate when the servicing umbilicals are removed and the suit reaches an internal pressure of {{convert|4.3|psi|kPa|abbr=on}}. A typical EMU can support an astronaut for 8½ hours, with 30 minutes of reserves in the case of primary life support failure.

==Comparison between Apollo A7L/A7L-B, Shuttle EMU, and Shuttle ACES suits==
Although the EMU is in many ways identical in appearance to the Apollo A7L space suits, and functions in the same manner as that of the Shuttle ACES suit, there are major differences in appearance and function.

{| class=wikitable
|-
!
!''[[Apollo/Skylab_A7L|A7L & A7L-B Suit]]''
!''Shuttle EMU Suit''
!''Shuttle [[Advanced Crew Escape Suit|ACES]] Suit'' 
|-
|''Manufacturer''
|[[ILC Dover]] (suit), [[Hamilton Sundstrand]] (backpack)
|Hamilton Sundstrand ([[Hard Upper Torso|HUT]] and hardware, including [[Primary Life Support System|PLSS]]), 
ILC Dover (Arm assemblies, gloves, LCVG, and Lower Torso Assembly (legs and boots), Thermal Micrometeoroid Garments (TMG)), 
Airlock (Helmet, EVVA, bearings, BSC, disconnects, etc.) 
|[[David Clark Company]]
|-
|''Main Functions''
|Protection from cabin fire and sudden depressurization when in Apollo CSM or LM and as an EVA space or moonwalking suit
|Protection from near-vacuum conditions during EVA
|Sudden depressurization during launch and entry while in Orbiter; bailout protection in controlled [[gliding (flight)|gliding flight]] below 50,000 ft.; water immersion for 24 hrs.
|-
|''First Used''
|1968 [[Apollo 7]]
|1983 [[STS-6]]
|1981 [[STS-1]] – a modified U.S. Air Force high-altitude pressure suit was used for the first four flight. 1995 – replacement for partial-pressure "Launch-Entry Suit" used since [[STS-26]] in 1988.
|-
|''Last Flight''
|1975 [[Apollo-Soyuz Test Project]]
|Still in Service
|1984 [[STS-4]] – reintroduced after [[Challenger Disaster]] as partial pressure "Launch-Entry Suit" (LES), replaced fleetwide with current ACES model in 1998.
|-
|''Features''
|One piece five-layer "torso-limb" suit augmented with a 3-layer "cover layer" made from [[Teflon]]-coated [[fiberglass]] thread for IVA (non-spacewalking) suits or a 17-layer "cover layer" for EVA (spacewalking) suits (A7L-B lunar suits had additional layers due to the longer surface EVAs, while A7L-B Skylab suits had fewer layers due to the near-Earth environment). First suits to use "bubble helmets" (eliminating the need for a visor seal), and communication ("[[Snoopy]]") caps and connectors allowing the suits to be hooked up to both the spacecraft and the life-support backpack at the same time.
|Two-piece 17-layer suit incorporating both the life-support and micrometeoroid protection. HUT has life support backpack and controls integrated in system. Uses same bubble helmet and communications cap from Apollo, although helmet is augmented with a EVA visor assembly incorporating lights and TV cameras.
|One piece five-layer "torso-limb" suit with a two-layer [[Nomex|NOMEX]] cover layer colored [[international orange]] for easy spotting in the case of an emergency Orbiter bailout in controlled gliding flight. First post-Apollo suit to incorporate a full-pressure helmet with a faceplate that can open and close, and augmented with a sunshade visor for glare protection from the sun. Inflatable bladders in legs act as "g-pants" for astronauts during reentry phase as a precaution against fainting.
|-
|''Weight'' (fully loaded)
|{{convert|245|lb|kg}} (A7L-B lunar suit)
|{{convert|195|lb|kg}} (current Shuttle/ISS version)
|{{convert|80|lb|kg}} (current model)
|-
|''Advantages and Disadvantages''
|Suits were custom-made for each astronaut, with each prime crew having three suits and each backup crew having two. Suits were worn only once for each mission, especially those in the last three Apollo flights when the fine powdery dust ground into the cover layers of the suits, turning the white suits in a deep gray color. Also, astronauts had to assist each other when donning the suits, especially with the A7L when the zipper ran vertically up and down the back of the suit (the A7L-B suit's zipper ran from the left hip, across and diagonally across the back to the right shoulder, allowing the astronaut to somewhat don the suit himself)
|Only the gloves have to be custom-made, costing over $40,000 [[USD]] for each pair—the suits can be reused up to 25 times with regular maintenance and are assembled from components based on the astronaut's height, weight, and body structure.
|Suits are custom-made for each astronaut, but, with proper maintenance, can be reused like their Air Force counterparts (used on both the [[Lockheed U-2|U-2]] and [[SR-71]] spyplanes). Suit can provide protection indefinitely up to 100,000 feet.
|-
|}

==Manufacturer==
The EMU hardware and accessories (PLSS, helmet, communications cap, and locking rings for the helmet and gloves), is manufactured by the [[Hamilton Sundstrand]] division of [[United Technologies]] out of [[Windsor Locks, Connecticut]], while the suit's soft components (the arms of the HUT and the entire LTU) are produced by [[ILC Dover]] out of [[Frederica, Delaware]]. The two companies, who were rivals during the early days of Apollo for the contract to build the "Block II" (moonwalking) space suit, teamed up in 1974 against the David Clark Company and [[AiResearch]] for the EMU development and construction. During Apollo, the ILC Dover-produced A7L used the [[Primary Life Support System|life support backpack]], helmet, and locking rings supplied by Hamilton United, but originally, ILC Dover was to just supply the arms and legs of the suit, a similar process that is still going on today.

==History==
Upon receiving the contract to build the EMU in 1974, Hamilton United and ILC Dover delivered the first EMU units to NASA in 1982. During the research and development phase (1975-1980), a suit being tested caught fire, injuring a technician and forcing a redesign on the regulator and circulation fan. The first EMU flew on [[STS-4]] in July, 1982, during which the astronauts practiced donning and doffing the suit in the Shuttle's airlock. The first Shuttle EVA was to occur on [[STS-5]], but an electrical failure on the circulation fan forced the EVA to be cancelled. The first EVA of the new EMU finally occurred on [[STS-6]] when [[Story Musgrave]] and [[Donald Peterson]] went out in the payload bay of the [[Space Shuttle Challenger]] and tested techniques to lower the launch cradle of a solid-fuel upper stage used to boost a [[Tracking and Data Relay Satellite]] (TDRS-A) into a geo-stationary orbit.

Other EVAs followed on the Shuttle, especially that on [[STS-41-B]] (the first [[Manned Maneuvering Unit]] flight), [[STS-41-C]] (the [[Solar Maximum Mission|Solar Max]] repair mission), and [[STS-51-A]] (where two stranded satellites were retrieved and returned to Earth), but the majority of the EMU's use occurred on the servicing missions of the [[Hubble Space Telescope]]. For those flights, two sets of EVA astronauts would venture out of the Orbiter, thus requiring NASA to fly four sets of suits (along with repair parts).

With the building of the ISS, Hamilton Sundstrand and ILC Dover refined the existing Shuttle EMU by making the suit modular. This allowed the EMU to be left on the ISS for up to 2 years and resized on-orbit to fit various crew members. They also made provisions for an increased capacity battery, the [[Simplified Aid for EVA Rescue]] (SAFER), improved cameras, radios and a new caution and warning system. Another feature incorporated into the new ISS suits are an additional battery to power heaters built into the glove, allowing astronauts to keep their hands warm during nighttime passages on each 95-minute orbit. Currently, the ISS EMU and the Russian ORLAN are used by crews of all nationalities on the International Space Station.

==Future use==
NASA will continue to use the EMU once the ISS is completed and the Space Shuttle is retired from active service in 2010. With the upcoming [[Project Constellation|Constellation Program]] to the ISS, [[Moon]], and [[Mars]] to commence in 2015, NASA has decided to replace the EMU and the ACES pressure suit with the new [[Constellation Space Suit]] system, which is derived from the ACES suit and the ILC Dover-developed and tested [[Mark III (space suit)|Mark III]] and [[I-Suit]] space suit systems.

The new suit, which is capable, depending upon the configration, of protecting the astronaut during launch, in-flight emergencies, reentry and landing, and both microgravity and lunar EVAs, will feature common hardware and the modular features used in the ACES and EMU suits. On June 11, 2008, NASA awarded a contract for [[Oceaneering International]] for the development and manufacturing of the new suits, with the [[David Clark Company]] and United Space Alliance being two of seven contractors in the new endeavor. Oceaneering beat out the Hamilton Sundstrand/ILC Dover partnership in the manufacturing of the new space suit.

==Images==
<center>
<gallery perrow="5">
Image:Soichi Noguchi spacesuit.jpg
</gallery>
</center>

==See Also==
* [[Simplified Aid for EVA Rescue|SAFER]]
* [[Hard Upper Torso]]
* [[Liquid Cooling and Ventilation Garment]]

== References ==
<references/>
{{cite book |title= US Spacesuits |last= |first= |authorlink= |coauthors= Kenneth S. Thomas & Harold J. McMann |year= 2006 |publisher= Praxis Publishing Ltd. |location= Chichester, UK |isbn= 0-387-27919-9 |url= http://books.google.com/books?id=cdO2-4szcdgC&source=gbs_navlinks_s |}}

==External links==
*[http://www.nasa.gov/audience/foreducators/spacesuits/home/clickable_suit_nf.html Learn About Spacesuits NASA]
* [http://history.nasa.gov/alsj/ILC-SpaceSuits-RevA.pdf ILC Spacesuits & Related Products]
* [http://quest.nasa.gov/space/teachers/suited/index.html Suited for Spacewalking Teacher's Guide]
* [http://www.nasa.gov/pdf/188963main_Extravehicular_Mobility_Unit.pdf NASA EMU PDF]
* [http://www.spaceflight.nasa.gov/gallery/images/shuttle/index.html Shuttle Mission Images]

{{space suit}}

[[Category:Human spaceflight]]
[[Category:American spacesuits]]

[[es:Unidad de Movilidad Extravehicular del Transbordador Espacial]]
[[fr:Extravehicular Mobility Unit (EMU)]]
[[pt:Unidade de Mobilidade Extraveicular]]