Figure: Space Shuttle main engines during testing
Each Space Shuttle consisted of three Space Shuttle Main Engines. The three SSME's, in conjunction with the Solid Rocket Boosters, provided thrust to lift the Orbiter off the ground for the initial ascent. The main engines continued to operate for 8.5 minutes after launch, the duration of the Shuttle's powered flight.
After the solid rockets were jettisoned, the main engines provided thrust which accelerated the Shuttle from 4,828 kilometers per hour (3,000 mph) to over 27,358 kilometers per hour (17,000 mph) in just six minutes to reach orbit. They created a combined maximum thrust of more than 1.2 million pounds.
As the Shuttle accelerated, the main engines burned 500,000 gallons of liquid propellant provided by the large, orange external fuel tank. The main engines burned liquid hydrogen - the second coldest liquid on Earth at minus 423 degrees Fahrenheit (minus 252.8 degrees Celsius) - and liquid oxygen.
For more information on the Space Shuttle Main Engines, click here.