NASA marked yet another milestone in preparations for the first mission of its new Space Launch System (SLS) rocket Feb. 28, conducting an RS-25 engine test at its highest power level for an extended period of time. The 500-second RS-25 test was conducted on the A-1 Test Stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. For the fourth time, NASA powered the engine to 113 percent of its original thrust design, this time for more than 430 seconds, about four times longer than any previous hot fire at that thrust level. The hot fire concluded a series of nine tests that began last August, using RS-25 developmental engine No. 0525. As with previous tests in the series, the Feb. 28 hot fire featured an RS-25 flight engine controller that will be used on an SLS mission. The controller is a key component of engine modifications made to help power SLS, being built as the world’s most-powerful rocket to carry humans deeper into space than ever, to such destinations as the Mo...