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EVA to EMU - Page 3

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Because of its compact size and simple design it was not abandoned.

During the Skylab program (1973-1974) the EMU was ready once again for another test in space. Versions of the EMU called the AMU and AME were used within the large area of the Skylab space station. Specially modified for safe use in the large station, it proved capable of allowing an astronaut to move with precision in weightlessness. During the lull between Skylab and the Space Shuttle, a design was created to replace the EMU called the IMLSS. This design placed rocket jets, and their fuel, in a compartment within a space suit. The IMLSS never reached the test phase possibly because it required a tether and because of the close proximity of fuel to the astronaut.

With the Space Shuttle, the EMU was finally given the chance to work in the dangerous environment of open space. However, by the 1980’s the EMU was developed into the Manned Maneuvering Unit (MMU). In effect, the EMU was now the MMU, and NASA called their EVA suits that remained tethered in some way to the Shuttle, EMU’s. In February of 1984, during STS-41B, the MMU was successfully tested in Earth orbit. Astronaut’s McCandless and Stewart both wore MMU’s while they deployed two satellites. Both men became the first Americans to EVA in orbit without a tether. The last time the MMU was used was during STS-51 in November of 1984, when it was used to retrieve two faulty satellites (Ironically the same satellites that were deployed by the STS-41B crew). After the Challenger disaster in 1986, use of the MMU was discontinued because it was seen as an unnecessary risk. The MMU worked flawlessly every time it was used in space.

By the 1980’s advancements in space suit technology now allowed astronauts to work in space for up to eight hours with reasonable comfort and precision. The longevity of the EMU, which is really a personal spacecraft for the astronaut, is what makes space walking truly possible (Otherwise we would have robots do our work? Why don’t we do this already? A well-trained human that can adapt to any scenario is still more efficient than any computer or robot.).

Today, astronauts do not use the MMU, but are still encased in the proven self-sustaining EMU suits. Specially built suits called ISS EMU’s were designed for EVA’s around the International Space Station (ISS) and are far lighter, and offer more mobility than the previous suits used during Apollo and early Shuttle missions. Another added feature is that each suit can be used at least 25 times; a cost effective feature during ISS construction.

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