Space Shuttle Main Engine
Aerojet Rocketdyne's Space Shuttle Main Engine (SSME) is the world’s most reliable and highly tested large rocket engine ever built, and operates at greater temperature extremes than any mechanical system in common use today. The SSME has achieved 100 percent flight success with a demonstrated reliability exceeding 0.9996 in over 1,000,000 seconds of hot-fire experience.
The SSME is a reusable, staged-combustion cycle engine. Using a mixture of liquid oxygen and liquid hydrogen, the SSME can attain a maximum thrust level (in vacuum) of 512,300 pounds which is equivalent to greater than 12,000,000 horsepower. The regeneratively cooled engine also features high performance fuel and oxidizer turbopumps that develop 69,000 horsepower and 25,000 horsepower, respectively, within compact envelops.
Ultra-high-pressure operation of the pumps and combustion chamber allows expansion of all hot gases through a high-area-ratio exhaust nozzle to achieve efficiencies never previously attained in a production rocket engine. These advantages allow a heavier payload to be carried without increasing the launch vehicle size.
The Space Shuttle Main Engine was upgraded to extend system robustness and reliability with the incorporation of the Large Throat Main Combustion Chamber (LTMCC). In conjunction with the LTMCC, new high pressure turbopumps and a redesigned powerhead were introduced as the SSME Block II configuration which launched in July 2001. The final upgrade to the Block II, introduced as the Advanced Health Management System (AHMS) and flown active in June 2007, would culminate into a factor of four improvement to engine safety when compared to earlier configurations.