October 5: Six of eight steps have been completed. NASA plans to conduct the final step, an 8-minute long hot fire test, in November.

October 13: Boeing is tentatively planning the hot fire test for November 14.


Just north of Interstate I-10 along the Gulf Coast of Mississippi is a gigantic, orange core stage that will soon be used to send NASA’s most powerful rocket ever to the Moon. The 212-foot-tall core stage of Space Launch System, the vehicle for Artemis lunar missions starting next year, is currently hoisted up on the red, white, and meatball’d B-2 Test Stand at Stennis Space Center.

Engineers at the space center in south Mississippi are responsible for ensuring that the giant fuel tank and RS-25 engines are ready for action before being transferred to Kennedy Space Center in Florida. Steps range from testing flight electronics to loading and draining 350 tons of rocket fuel.

The ultimate step in the Green Run test is to fire up the four Aerojet Rocketdyne RS-25 engines fueled by the core stage. The static fire test will occur for up to eight minutes, creating a thunderous roar as the SLS core stage is held down by the B-2 Test Stand. Make no mistake: This engine test fire will be epic.

So how far along is NASA’s Green Run test for the Space Launch System core stage? Follow along here as NASA completes each step of the Green Run test:

SLS core stage

SLS core stage arrives at Stennis Space Center in Mississippi via NASA’s Pegasus barge. Boeing builds the rocket core stage in New Orleans for NASA at its Michoud Assembly Facility before it arrives by water at the B-2 Test Stand.

Prior to installing the actual SLS core stage at the B-2 Test Stand at Stennis Space Center, NASA tested its infrastructure with a test unit called Pathfinder that was used to simulate the size and weight of the real deal.

Following a successful Green Run test, Pegasus will transport the SLS core stage from Stennis Space Center to Kennedy Space Center in Florida. The core stage will travel from the Gulf of Mexico through the Atlantic Ocean before final assembly with Space Launch System at NASA’s Vehicle Assembly Building.

Space Launch System will be used to send the Orion spacecraft to space for the first Artemis mission as soon as 2021. The uncrewed mission around the Moon will launch from Launch Complex 39B just like Apollo 10, the fourth crewed Apollo flight and very first launch from LC-39B in 1969.

What to know

  • The test is called Green Run to denote the “new” flight hardware that hasn’t previously been tested
  • B-2 Test Stand was previously used for testing Saturn V rocket stages for Apollo missions and later RS-25 engines for Space Shuttle
  • The four RS-25 engines will create 1.6 million pounds of thrust during the static fire test β€” but the core stage won’t go anywhere if everything goes as planned
  • The core stage Green Run test will pave the way for the first woman and next man to walk on the Moon (NASA hopes to accomplish this by 2024)
  • Space Launch System will ultimately be used for NASA missions to Mars

Green Run progress

πŸ€ Green Run test steps Status
πŸ’₯ Modal Test: Apply forces simulating launch to the unpowered, suspended core stage Complete
⚑️Avionics: Turn on and check out core stage avionics Complete
⚠️ Fail-Safes: Simulate potential issues to test systems that shut down other systems if there’s a problem Complete
πŸŽ› Propulsion: Test main propulsion system components that connect to the engines Complete
πŸ’« Thrust Vector Controls: Test thrust vector controls and check out all the related hydraulic systems Complete
⏰ Countdown: Simulate launch countdown to validate timeline and sequence of events Complete
⛽️ “Wet” Dress Rehearsal: Load and drain more than 700,000 pounds of cryogenic propellants Up Next
πŸ”₯ Hot Fire: Fire all four RS-25 engines for up to 8 minutes November
Source: NASA Last updated: October 13, 2020, 10 a.m. EDT
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When will the core stage static fire test occur?

NASA doesn’t publish dates for when each step of the Green Run test will be conducted, only when each step is completed.

In February, engineers at Stennis Space Center expected the static fire test to occur in July or August, then work at SSC shut down for several weeks due to the COVID-19 pandemic. Work on the Green Run test resumed in May, so we hope to see the static fire test around November.

NASA currently plans to fly Space Launch System for Artemis I by the end of 2021.

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Excited for the Artemis program and Space Launch System? Want to know more about the core stage Green Run tests and the B-2 Test Stand? Let us know in the comments!

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