NASA test fires hybrid rocket motor

akey writes "According to this CNN article, NASA engineers test fired a new hybrid rocket motor. It's not as combustible on its own as conventional solid-fuel motors, and much less expensive than liquid engines, and allegedly produces fewer noxious emissions than solid-fuel motors. An added bonus is that for the motor to burn, an oxidizing agent must be continuously injected -- unlike other solid-fuel motors, it can be turned off after ignition if necessary. It won't be ready for use on a scale for the Space Shuttle for a few years yet, but it's showing promise. "