MMU another victim of shuttle----such waste is unbelievable

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

by Anne Millbrooke

In 1984 a Manned Maneuvering Unit (MMU) enabled a few astronauts to maneuver in outer space, outside of spacecraft, and free of tether lines. This manned maneuvering unit and its predecessors are, as the name implies, maneuvering devices. Flight is the function of the spacecraft. Life support is the function of the space suit. Maneuvering is an extravehicular activity independent of the protective and supportive space suit, yet integrated with the suit and even the spacecraft. The spacecraft and space suit are prerequisites to extravehicular activity, the craft to transport the astronaut into outer space, and the suit to protect and support life. The maneuvering unit is an optional aid. The maneuvering unit, spacecraft, and space suit are complementary components of the human space flight program. Whereas all such space flights have involved spacecraft and space suits, only a few have utilized manned maneuvering units.

Outer space is a micro- or zero-gravity environment that requires special techniques for moving inside the spacecraft as well as out. Based upon experience aboard the Space Shuttles Columbia and Discovery, astronaut Joseph P. Allen described the experience inside a spacecraft:
 

During the first few days in space, the act of simply moving from here to there looks so easy, yet is so challenging. The veteran of zero gravity moves effortlessly and with total control, pushing off from one location and arriving at his destination across the flight deck, his body in the proper position to insert his feet into Velcro toe loops and to grasp simultaneously the convenient handhold, all without missing a beat in his tight work schedule. In contrast, the rookies sail across the same path, usually too fast, trying to suppress the instinct to glide headfirst and with vague swimming motions. They stop by bumping into the far wall in precisely the wrong position to reach either the toe loops or the handholds.1

Space writer Harry L. Shipman expressed this more directly: "Velcro takes the place of gravity" inside the spacecraft.2 Outside the spacecraft, there is no Velcro and no enclosing walls. Civilian and military engineers thus explored various mechanism to aid astronauts outside the spacecraft. These aids included foot restraints, hand grips, tether lines, and self-propelled maneuvering units, yet few space missions required the technology and capability of manned maneuvering units.

Floating in space was a lesson learned by experience gained gradually during the Mercury, Gemini, Apollo, Skylab, and Space Shuttle missions. In fact, the Mercury,