SLS rocket proceeding to final stage of 'Green Run' test series

NASA on Wednesday is targeting the final test in its Green Run series, the hot fire, for as early as January 17.

The hot fire is the culmination of the intensive, comprehensive Green Run test series, an eight-part campaign that gradually brings the core stage of the Space Launch System (SLS) — the world’s most powerful ever rocket that will power America’s next-generation human moon missions and subsequent crewed missions to Mars — to life for the first time.

Alabama’s aerospace industry has led the effort to build the SLS, which stands 212 feet high and 27.6 feet in diameter.

Boeing is the core stage lead contractor, and Aerojet Rocketdyne is the RS-25 engines lead contractor. The SLS program is managed out of NASA’s Marshall Space Flight Center in Huntsville, while Boeing’s Huntsville-based Space and Launch division manages the company’s SLS work.

NASA conducted the seventh test of the Green Run test series – the wet dress rehearsal – days before Christmas at NASA’s Stennis Space Center in Mississippi.

This marked the first time cryogenic, or super cold, liquid propellant was fully loaded into, and drained from, the SLS core stage’s two immense tanks. The wet dress rehearsal provided structural and environmental data, verified the stage’s cryogenic storage capabilities, demonstrated software with the stage’s flight computers and avionics, and conducted functional checks of all the stage’s systems. The end of the test was automatically stopped a few minutes early due to timing on a valve closure. Subsequent analysis of the data determined the valve’s predicted closure was off by a fraction of a second, and the hardware, software and stage controller all performed properly to stop the test. The team has corrected the timing and is ready to proceed with the final test of the Green Run series.

“During our wet dress rehearsal Green Run test, the core stage, the stage controller, and the Green Run software all performed flawlessly, and there were no leaks when the tanks were fully loaded and replenished for approximately two hours,” stated Julie Bassler, SLS stages manager at Marshall Space Flight Center. “Data from all the tests to date has given us the confidence to proceed with the hot fire.”

The upcoming hot fire test will fire all four of the stage’s RS-25 engines simultaneously for up to eight minutes to simulate the core stage’s performance during launch.

After the firing at Stennis, the core stage for SLS will be refurbished and shipped on the agency’s Pegasus barge to NASA’s Kennedy Space Center in Florida. The stage will then be assembled with the other parts of the rocket and NASA’s Orion spacecraft in preparation for Artemis I — the first integrated flight of SLS and Orion and the first uncrewed mission of the agency’s Artemis program.

“The next few days are critical in preparing the Artemis I rocket stage, the B-2 Test Stand at NASA’s Stennis Space Center, and the test team for the finale of the Green Run test series,” added Barry Robinson, project manager for SLS core stage Green Run testing at Stennis. “The upcoming Green Run hot fire test is the culmination of a lot of hard work by this team as we approach a key milestone event for NASA’s Artemis missions.”

Testing the SLS rocket’s core stage is a combined effort for NASA and its industry partners, led by Boeing and Aerojet Rocketdyne.