On January 9th, NASA tested the RS-25 engine that will power their new rocket, the Space Launch System (SLS) into deep space. During the test, the RS-25 fired away for eight and a half minutes while NASA engineers recorded data on the engine controller unit and inlet pressure conditions. The engine controller unit allows communication between the vehicle and the engine and provides closed-loop management of the engine by regulating the thrust and fuel mixture ratio.
This was the first hot fire of an RS-25 engine (formerly called Space Shuttle Main Engine) since the space shuttle main engine testing ended in 2009. In the future, four RS-25 engines will power the SLS on missions to asteroids and Mars.
