I'm an Aerospace Technician for United Space Alliance. I work in the Aft shop where we're in charge of everything behind the Shuttle cargo bay. All of the propulsion systems; SSME Main engines, Orbital ManeuveringSystem engines and the Reaction Control System thrusters. We also work on the Auxiliary Power Units which supply hydraulic power and the water spray boiler and flash evaporator which cool the hydraulic fluid at different altitudes. We have three avionics bays, a gazillion miles of wiring and all of the electrical andmechanicalinterfaces with the external tank.