The Extravehicular Mobility Unit (EMU) is an independent anthropomorphic spacesuit that provides environmental protection, mobility, life ...
The Extravehicular Mobility Unit (EMU) is an independent anthropomorphic spacesuit that provides environmental protection, mobility, life support, and communications for astronauts performing extra-vehicular activity (EVA) in Earth orbit. Introduced in 1981, it is a two-piece semi-rigid suit, and is currently one of two EVA spacesuits used by crew members on the International Space Station (ISS), the other being the Russian Orlan space suit... Suit components The EMU, like the Apollo/Skylab A7L spacesuit, was the 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, arm sections, gloves, an Apollo-style "bubble" helmet, the 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 incontinence diaper – Urine Collection Devices (UCDs) are no longer used), and possibly a Thermal Control Undergarment (long johns). The final item donned before putting on the pressure suit is the Liquid Cooling and Ventilation Garment (LCVG)... After donning the LCVG, the astronaut then puts on the LTA, before entering the airlock. The astronaut then dons the HUT, connects the LCVG umbilical to the umbilical in the HUT, and then locks the two parts of the suit together using the Body Seal Closure. Once the suit is turned on and checked out, the astronaut dons a "Snoopy cap", a brown and white fabric communications cap dating back to the Apollo days, which 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 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 4.3 psi (30 kPa). A typical EMU can support an astronaut for 8.5 hours, with 30 minutes of reserves in the case of primary life support failure. To perform an EVA from the shuttle, the cabin pressure was reduced from 14.7 psi to 10.2 psi for 24 hours, after which an astronaut had to pre-breathe for 45 minutes. For EVAs on board the ISS, the astronaut must pre-breathe for about four hours... Manufacturer The EMU hardware and accessories (PLSS, helmet, communications cap, and locking rings for the helmet and gloves), is manufactured by Hamilton Standard (now the Hamilton Sundstrand division of UTC Aerospace Systems) 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 (a former division of Playtex) out of Frederica, Delaware... 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... 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, notably those on STS-41-B (the first Manned Maneuvering Unit flight), STS-41-C (the Solar Max repair mission), and STS-51-A (where two stranded satellites were retrieved and returned to Earth), but the majority of EMU uses occurred on the servicing missions of the Hubble Space Telescope... 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 two years and resized on-orbit to fit various crew members... Currently, the ISS EMU and the Russian ORLAN are used by crews of all nationalities on the International Space Station. The two EMUs are stored within the Quest Joint Airlock. Future use and proposed replacement NASA continues to use the EMU on the ISS but a Z series suit may eventually take its place... Less
