In this historical photo from the U.S. space agency, a Linear Aerospike engine to be used for propulsion for the X-33 Reusable Launch vehicle (RLV) is shown being tested on April 27, 1997. A testing of three thrust cells of Linear Aerospike engines was conducted to investigate injectors, chambers, and Aerospike ramps at Marshall Space Flight Center (MSFC).
The X-33 was intended to demonstrate advanced technologies that would dramatically increase launch vehicle reliability and lower the cost of putting a pound of payload into space.
Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).