A spacecraft reaction-control-system (RCS) thruster now undergoing development generates a thrust of 870 lbf (3,870 N) by burning ethanol and liquid oxygen (LOX), which are nontoxic. The performance of the thruster has been tested in operation in multiple pulse modes with pulses as short as 160 ms; such pulses are typical of those required for the space-shuttle RCS.

This test is the first successful demonstration of a liquid/liquid-fed thruster in pulse-mode operation. The use of thrusters fed by nontoxic liquids is expected to afford great benefits - not only in space-shuttle operations but also in the operations of reusable first-stage or liquid-fueled fly-back boosters or, indeed, of any reusable launch vehicle currently produced by NASA or the Department of Defense.

Today, the market for thrusters like this one is limited to the second-stage RCS and orbital maneuvering system of the Kistler K-1 vehicle (a commercial reusable launch vehicle), to the RCS of the VentureStar reusable launch vehicle, and to upper-stage RCSs in general; however, with the increase in the number of commercial aerospace companies launching unmanned rockets, the technological advances made in the development of this thruster can be expected to affect the commercial field significantly. For NASA, the use of LOX and ethanol in the shuttle RCS thrusters will not only increase safety but will also reduce costs.

This work was done by Paul Philipsen, Lee May, and Ross Hewitt of GenCorp for Johnson Space Center.