The company is also considering a smaller spaceplane derived more directly from X-37. The world's most powerful hybrid rocket motor was successfully test fired at NASA's Stennis Space Center in Mississippi on August 13. The 250,000 pound thrust motor ran for 15 seconds on the center's E-1 test stand. The motor was designed and constructed by the Hybrid Propulsion Demonstration Program consortium. Consortium members include Lockheed Martin Astronautics, Boeing Rocketdyne, Lockheed Martin Michoud Space Systems, Thiokol Corporation and United Technologies Chemical Systems Division.
Hybrid motors use solid fuel and a liquid oxidizer.
The oxidizer is injected into the head end of the solid fuel section where combustion occurs. Hybrid motor thrust can be terminated and, potentially, throttled to some extent. The motors are inherently safer than other solid rocket motors and may prove to be less expensive to produce. Hybrid motors, in return, are heavier and less efficient than other solid motor types. The extension lasts through 2001.