The RS-25 test this afternoon just fired up for 535 seconds, about the amount of time the engines will fire during an actual launch. This is one of four engines that will power the core stage of NASA’s new Space Launch System (SLS), and carry the agency’s #Orion crew capsule as part of the journey to Mars and other deep space destinations. It was AWESOME. Credit: NASA #SLSFiredUp #JourneyToMars #NASA #Stennis #SLS #mississippi #NASASocial