America's next heavy-lift rocket needs a strong and reliable engine to launch humans beyond low Earth orbit. That's why engineers with NASA's Space Launch System program, managed at the Marshall Space Flight Center in Huntsville, AL, will use the proven RS-25, the space shuttle's main engine during its 30-year history, to power the massive rocket's core stage. The RS-25, which was designed and developed with NASA by Pratt & Whitney Rocketdyne of Canoga Park, CA, is a crucial part to the core stage design, but a few enhancements are planned.
While the RS-25 engines launched 135 missions, it needs a new "brain" to drive the 3.5-ton engine. The role of an engine controller unit is to allow communication between the vehicle and the engine, sending commands down to the engine and transmitting data back to the vehicle. The controller also provides closed loop management of the engine by regulating thrust and fuel mixture ratio while monitoring the engine's health and status.
Engineers with Pratt & Whitney Rocketdyne are hard at work on the J-2X engine control unit in Building 4436 at the Marshall Center. The J-2X will power the upper stage of the evolved heavy-lift rocket, capable of lifting 130 metric tons beyond low Earth orbit.
Meanwhile, in a separate room barely 20 feet away, the same controller with a few minor alterations is undergoing rigorous testing for the RS-25. This room houses equipment to simulate the engine in flight, using real RS-25 actuators, connectors and harnesses.