SPACEMART
Tiny Propulsion System Targets Future Microsatellites

The MEMS design, based on silicon chip fabrication technology, offers several advantages over conventional thrusters: It has no moving parts, utilizes a variety of propellants, is scalable, eliminates the need for tanks, fuel lines and valves, and fully integrates the structure of the satellite with the propulsion to power it.
photo copyright Aerospace Corp
Redondo Beach - May 16, 2001
A micro-thruster array measuring one-quarter the size of a penny, designed by a TRW-led team for use on micro-, nano- and pico-satellites, has successfully demonstrated its functionality in a live fire test aboard a Scorpius sub-orbital sounding rocket.

Individual micro-electromechanical system (MEMS) thrusters, each a poppy seed-sized cell fueled with lead styphante propellant, fired more than 20 times at 1-second intervals during the test staged at the White Sands Missile Range. Each thruster delivered 10-4 Newton seconds of impulse.

"The test proves the technology behind this micro-thruster is well along in its development," said David H. Lewis, Jr., TRW's MEMS Digital Micro-Propulsion project manager.

"We're very pleased with its performance at White Sands. We believe micro-thrusters have the potential to provide on-orbit propulsion for station keeping, orbital correction and attitude control for future, very small satellites weighing from less than a pound to as much as 50 pounds."

The MEMS design, based on silicon chip fabrication technology, offers several advantages over conventional thrusters: It has no moving parts, utilizes a variety of propellants, is scalable, eliminates the need for tanks, fuel lines and valves, and fully integrates the structure of the satellite with the propulsion to power it.

The micro-thruster is being developed by TRW and teammates Caltech and the Aerospace Corp. under a contract from the Defense Advanced Research Projects Agency.

The MEMS micro-thruster arrays are fabricated as a three-layer silicon and glass sandwich, with the middle layer consisting of multiple small propellant cells sealed with a rupturable diaphragm on one side and an ignitor on the other.

Each cell is a separate thruster, and when ignited, delivers one impulse bit. Delivering propulsion in discrete increments by igniting thrusters in controlled sequences has lent the technology the name "digital propulsion."

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DRAGON SPACE
China Studying Novel Steam Engine For Micro Probes
Tsinghua - March 21 2001
Gentle puffs of steam could one day propel tiny spacecraft round the cosmos, say space scientists in Beijing. Steam power would provide a green alternative to toxic fuels in miniature rocket motors.
SPACE.WIRE