NASA continues to test the RS-25 engines that will send astronauts atop the Artemis rocket, known as the Space Launch System, to the moon. [Watch the rocket engine test at the top of this story]NASA says the tests will provide important data for Aerojet Rocketdyne as the contractor begins building new RS-25 engines for future SLS flights. LIVE: Watch an RS-25 engine that will help power our @NASA_SLS rocket on future missions to the Moon and Mars come alive at @NASAStennis. At this rate, the 212-foot core stage made by Boeing is down to about six “tanks” on its lifespan. In a news release regarding the RS-25 engine testing, NASA said the Green Run team continues to evaluate if a second hot fire test of the core stage is required.