Advanced Crew Escape Suit
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The Advanced Crew Escape Suit or ACES suit, is a full pressure suit currently worn by all Space Shuttle crews for the ascent and entry portions of flight. The suit is a direct descendant of the U.S. Air Force high-altitude pressure suits worn by SR-71 Blackbird and U-2 spy plane pilots, X-15 and Gemini pilot-astronauts, and the Launch-Entry Suits worn by NASA astronauts starting on the STS-26 flight, the first flight after the Challenger Disaster. The suit is manufactured by the David Clark Company of Worcester, Massachusetts.
[edit] History
The ACES suit was first worn by U.S. Air Force pilots in the mid-1970s, replacing a similar suit worn by SR-71 and U-2 pilots, and was identical to the suits worn by X-15 pilots and Gemini astronauts. Unlike the ACES suit, which is a full-pressure suit, the high-altitude suits were partial pressure suits, thus requiring a rubber diaphragm around the wearer's face. With the development of the Space Shuttle, and the inclusion of ejection seats on the Space Shuttle Columbia on the first four flights (STS-1 to STS-4), NASA decided to adopt modified versions of the suit; the modifications being the attachments to the parachute harness, and the adoption of inflatable bladders in the legs to prevent the crew from passing out during reentry. One other modification, a mount for prescription glasses, was incorporated for astronaut John W. Young, who wore modified bifocal reading glasses (resembling aviator sunglasses, but with the top portion, usually for distance seeing, being of regular glass, and the bottom, for reading, of the wearer's prescription) during the flight.
The four test flights, between April 1981 and July 1982, went without incident, and the pressure suits performed without any problems. With the termination of the test flight program, all crews from STS-5 to Challenger (STS 51-L) saw the crew wearing one-piece light blue flight suits, escape harnesses, and helmets similar to the pressure suit helmets, but fitted around the head with a clamshell-like closure. After Challenger, NASA, in need of an escape system, also required the reintroduction of the wearing of pressure suits during the launch and landing portions of the flight.
For STS-26, the astronaut crew wore the new launch-entry suits (LES), which resembled the SR-71 suits, but with most of the padding and survival gear removed, the addition to pressure bladders in the legs, and the absence of locking rings on the wrists—gloves were zippered on similar to Alan Shepard's MR-3 suit, and a new helmet, which has no padding, allowing free movement of the head, was incorporated. A survival backpack, containing a parachute, escape pole ring (similar to a parachute static line), 30 minutes of oxygen, and a life raft, was worn prior to entering the orbiter. Because of the new helmet design, astronauts were required to wear a communications cap similar to those worn by Apollo astronauts, and because they were white (later changed to brown), the suit resembled the Vostok pressure suit, called SK-1, worn by Yuri Gagarin, but without the "CCCP" letters on the helmet. The suits were designed to withstand pressures up to 40,000 feet (12 kilometers), and submersion in the ocean for up to 24 hours at 40 degrees Fahrenheit (5 degrees Celsius).
Although the LES suit was a functional suit, it was a partial pressure suit, and NASA astronauts and engineers were looking for a more durable suit, thus in 1995, the ACES suit was introduced. Resembling the LES, the ACES suit differs with the inclusion of detachable gloves locked onto locking rings, and changes to incorporate liquid cooling and ventilation. The ACES suit is currently the only suit worn by NASA for all Shuttle flights, and may be used when the new Crew Exploration Vehicle is introduced after the 2010 retirement of the Shuttle fleet, although NASA may look into alternatives.
[edit] Current specifications
The ACES suit used by Shuttle astronauts is similar in design to the Gemini spacesuit worn by the astronauts between 1965-1966 and by the three Apollo 1 astronauts in 1967. The components of the ACES consists of the following:
- A one-piece pressure garment assembly with integrated pressure bladders and ventilation system. Oxygen is fed through a connector at the wearer's left thigh and is transmitted to the helmet, via a special connector at the base of the neckring. The helmet and gloves are connected to the suit, via locking rings in a metallic gray in color (Gemini suits featured a gray neck ring and red and blue anodized glove rings). The suit has a Nomex cover layer in international orange color, instead of silver or white as in previous David Clark suits. The orange color allows rescue units to easily spot the astronauts in the case of an Orbiter bailout over the ocean.
- A full pressure helmet with a locking clear visor and a black sunshade worn to reduce any glare from reflected sunlight, especially during the approach and landing phases of the mission. A communications cap (originally white, but since changed to dark brown and identical to those worn by the Russian cosmonauts with the Sokol space suits worn aboard Soyuz missions), is worn underneath the helmet, and connected to a special plug inside the helmet, in which is then connected to the intercom system in the Orbiter, similar to the communications "pigtail" on the old Mercury helmets. An anti-suffocation valve at the back of the helmet allows for the passing of carbon dioxide from the helmet. The helmet's clear pressure faceplace is locked into place with mechanical seal with a prominent "lockdown" bar which can be easily reached with gloved hands.
- The gloves are also attached via a locking ring and are likewise in international orange color. When the suit pressurizes, the gloves are also pressurized. The palm of the gloves are textured to allow crews to throw switches, push buttons, turn knobs (especially the "ABORT MODE" knob on the commander's panel), and for the Commander and Pilot, operate the flight control stick during the final approach during landing.
- Heavy black leather "paratrooper" boots with zippers instead of laces—no cloth is used in the case of fire, and to reduce ankle and foot injuries.
- Survival backpack, which is donned before entering the orbiter.
Each suit weighs a total of 80 lb (35 kg), and is sized individually, although most suits can be worn by astronauts of different heights. No ACES suit has failed during normal flight situations, although the Columbia Accident Investigation Board said that the suit, if fully pressurized, would have been useless in the Columbia accident, as the Columbia's crew cabin broke apart at the extreme altitude of over 170,000 feet (32 miles or 52 kilometers) above the Earth—the ACES suit can function, outside of the orbiter, below 50,000 feet (9.5 mi./15 km.), which is the upper limit of controlled bailout procedures. Investigations on parts of several suit components that were recovered showed that some crew members did not have their gloves on, and that one astronaut was not wearing his pressure helmet. The infamous photograph of the space suit helmet found after the accident revealed that the recovered helmet was attached to the suit and the visor was down--indicated by the "lockdown" bar going across the bottom of the helmet, where it connects to the ring. Both the pressure faceplate and the sunshade were missing, indicating that they were destroyed either by the hypersonic wind blast when the pressure module was destroyed or by the intense heat.
[edit] External links
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| American models | Navy Mark V • Gemini Space suit • MOL Space suit • Apollo/Skylab A7L • Extravehicular Mobility Unit • Advanced Crew Escape Suit |  |
| Russian models | SK-1 • Yastreb • Krechet • Sokol • Orlan • Strizh | |
| Developing technologies | Mark III • I-Suit • Bio-Suit • Space activity suit | |
| Components | Hard Upper Torso • Liquid Cooling and Ventilation Garment • Primary Life Support System • Thermal Micrometeoroid Garment | |
| Related topics | Extra-vehicular activity • Manned Maneuvering Unit • Pressure suit | |
