ANSWER: Space

Liquid Hydrogen and Liquid Oxygen

The Space Shuttle main engines burn liquid hydrogen and liquid oxygen from the Space Shuttle external tank. They are used for propulsion during its ascent, in addition to the two more powerful solid rocket boosters and partly the Orbital Maneuvering System. Each engine can generate almost 1.8 meganewtons (MN) or 400,000 lbf of thrust at liftoff. The engines are capable of generating a specific impulse (Isp) of 453 seconds in a vacuum, or 363 seconds at sea level (exhaust velocities of 4440 m/s and 3560 m/s respectively). Overall, a space shuttle main engine weighs approximately 3.2 t (7,000 lb). The engines are removed after every flight and taken to the Space Shuttle Main Engine Processing Facility (SSMEPF) for inspection and replacement of any necessary components. The cost of each SSME is approximately $40 million USD.

Matt: CORRECT
Record: 317-270