NASA to retain SLS Green Run test

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WASHINGTON — Four months after suggesting a critical test for the Space Launch System could be skipped to address development delays, NASA Administrator Jim Bridenstine said July 25 that the test will be retained.

In an agency statement, Bridenstine announced that NASA will proceed with the “Green Run” test of the SLS, where its core stage performs an eight-minute static-fire test at the Stennis Space Center in Mississippi. NASA did not disclose when the test will take place, although it’s widely expected to be some time next year.

“The Green Run acceptance test gives NASA the confidence needed to know the new core stage will perform again and again as it is intended,” Lisa Bates, SLS deputy stages manager at NASA, said in that statement.

However, at a March 27 hearing of a House appropriations subcommittee, Bridenstine suggested the test may not be necessary. “Could we test each engine individually at very high off-nominal kinds of conditions to get certainty, or at least eliminate as much risk, or almost as much risk, as we would if we ran the Green Run?” he said.

At that hearing, a day after Vice President Mike Pence announced that the administration was setting a new goal of landing humans on the moon by 2024, four years earlier than previously planned, Bridenstine said NASA was studying ways to accelerate development of the SLS. Skipping the Green Run test, he said, could move up the date for the first SLS launch by six months.

Both members of Congress and outside advisors pushed back against that proposal, though. “There is no other test approach that will gather the critical full-scale integrated propulsion system operational data required to ensure safe operations,” Patricia Sanders, chair of the Aerospace Safety Advisory Panel, said of the Green Run test at an April 25 meeting of the committee. “I cannot emphasize more strongly that we advise NASA to retain this test.”

In subsequent months, NASA officials had said they had not reached a decision about the Green Run, but hinted that they were looking to retain it, at least in some form. In recent interviews and testimony, Bridenstine had said he would wait until new leadership was in place at the Human Exploration and Operations Mission Directorate, after the surprise reassignments of Bill Gerstenmaier and Bill Hill July 10, before deciding whether to conduct the test.

“I want to make sure we get those top people in place and then let them look at the program,” Bridenstine said in a July 12 interview on C-SPAN. “Ultimately we’ll let them make the determination of what tests needs to be done.”

NASA has yet to find permanent replacements for Gerstenmaier, who has been the associate administrator for human exploration and operations, or Hill, the former deputy associate administrator for exploration systems development. The agency didn’t explain why it made its Green Run decision now.

The decision, though, was welcomed by many. “Administrator Bridenstine’s decision to go forward with the Green Run is a vote of confidence in Stennis Space Center and its dedicated workforce,” said Sen. Roger Wicker (R-Miss.), chairman of the Senate Commerce Committee. He asked Bridenstine about the test during a July 17 hearing by his committee, and Bridenstine again responded that he would wait until a new team was in place before making that decision.

“We’re very excited about the decision to continue with the core stage Green Run test,” said Richard Gilbrech, director of Stennis. The center had already modified the B-2 test stand at the center, used previously for tests of the Saturn V and space shuttle main engines, to support the core stage.

“With all modifications complete, Stennis is ready to test the core stage and support the agency as we go forward to the moon as a stepping stone to Mars with the Artemis program,” he added.