Space Transportation System, Space Shuttle Main Engine, Lyndon B. Johnson Space Center, 2101 NASA Parkway, Houston, Harris County, TX

Significance: The Space Shuttle used three Space Shuttle Main Engines (SSMEs) mounted to the orbiter. The SSME was designed and developed under a contract with the NASA Marshall Space Flight Center, Huntsville, Alabama. The contract was awarded in 1971 to the Rocketdyne Division of North American Rockwell Corp., Canoga Park, California. In late 2005, Pratt & Whitney purchased Rocketdyne from the Boeing Company. Rocketdyne was combined with the rocket engine contingent of Pratt & Whitney, West Palm Beach, Florida to form a division named Pratt & Whitney Rocketdyne.
The SSME was a large reusable liquid rocket engine which used liquid hydrogen as fuel and liquid oxygen as oxidizer. Both propellants were stored in the External Tank. The SSME operated using the staged-combustion cycle, meaning propellants were initially burned in preburners in order to power the high-pressure turbopumps and were then burned again at a higher mixture ratio in the main combustion chamber. This cycle yielded a specific impulse substantially higher than previous rocket engines thus minimizing volume and weight for the integrated vehicle. Along with high efficiency and low weight came system complexity, high turbopump speeds, high chamber pressures, and a high thrust-to-weight ratio of sixty-six at full power level. ...
Survey number: HAER TX-116-I