While the Shuttle is in space flight is the fuel that is used is burned or just jettison for thrust?
ANSWER from Mike Wilhoit on December 3, 1997: The fuel used to maneuver the Shuttle while on orbit is indeed burned and is different stuff than what is used in the main engines during the eight and a half minutes of launch. The maneuvering fuel and oxidizer are hypergolic, which means that they will ignite merely by contacting each other, without an extra ignition source. The main engines use liquid hydrogen and liquid oxygen and require an electronically produced spark to catch fire. There are igniters, which are like fancy spark plugs, in several locations on each engine because the propellants are “pre-burned” to help drive the liquid pumps, then remixed and burned again in the main combustion chamber. What you see coming out of these engines during launch is a slightly fuel-rich steam, mostly water. Return to top.
