Inside the space shuttle, for instance, heavy devices suck in gas to test for a dangerous buildup of hydrogen.
Enter the microscopic machines. They perform the same function as the old, clunkier technology, but with devices only the size of a piece of sand.
Post them around the shuttle and you save precious pounds on the shuttle and get the same, if not better, result. You can place so many of them that you can pinpoint when and where a dangerous buildup originates, rather than simply know that one exists.
While the concept of micro-machines has been around for years, the launch of the shuttle mission STS-93 marked the first time they have been tested in an outer space environment.
Initial results point to success, say officials and scientists involved, suggesting that micro-sized satellites and tiny super-sensors could be developed and used in space missions within the next several years.
The only thing jumbo-sized about them is the name: micro-electromechanical systems. Nicknamed MEMS, they rely on the same silicon-based design as computer chips.
But instead of using silicon wafers that are inches-wide, MEMS are miniaturized through a special manufacturing process to the size of a grain of pollen, practically invisible to the eye.
Their size yields tremendous advantages for the space program.
Sensors could be posted up throughout a spacecraft, indicating exactly when and where there is a potentially deadly leak.
Microgyros and accelerometers could relay precise data on the maneuvering of the spacecraft, replacing larger and heavier instruments that take up precious room on board the craft.
Even the craft itself can be shrunk by stacking different kinds of MEMS together and adding a power source to build a scientifically-valid microsatellite. Once built, it could be launched like a cannonball and maneuvered around space with a micro-sized thrusters.
More magic of MEMS: the devices can be mass-manufactured inexpensively, cutting back on labor and materials costs.
Taken to their logical extreme, MEMS could turn the space program -- now reliant on expensive, elephantine equipment -- upside down. What's big would become small, what's heavy would become light, and what's expensive would now be cheap.
One of the newest MEMS devices to be developed is a microthruster, a simple but powerful tool for propelling small satellites around space.
Think of them like tiny boxes -- so small that over thirty could fit on top of a penny -- each filled with a dot of fuel. Astronomers could attach them to a microsatellite and ignite a set of boxes to send the craft hurtling through space in a specific direction and at a pre-designed speed.
That project is being developed by the firm TRW, the military-funded Aerospace Corporation, and the California Institute of Technology.
More tests of the microthrusters are planned for shuttle mission STS-109, scheduled to go up in mid-2001.
Money for microthrusters and several other MEMS devices currently in development comes from the Department of Defense.
While their technology is breathtaking, MEMS have a more mundane appeal to the military: money.
"The big thing is reducing the weight of satellites," said Capt. Tom Hoge, an officer at the Air Force's Space Test Office. "Reduce the weight and you reduce the cost -- that's the military's big interest."
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