SLS Hot Fire Test a Success on Second Try

SLS Hot Fire Test a Success on Second Try

Today’s second test of the Space Launch System (SLS) core stage appears to be a complete success, although engineers must review all the data before making a definitive determination. The first attempt in January ended after just 67 seconds because of conservative test parameters that were set.  Not so today. The four RS-25 engines actually exceeded the 485 second goal, firing for 499.6 seconds.

This was the final test in a series of eight “Green Run” tests of the Boeing-built SLS core stage and its four Aerojet Rocketdyne RS-25 engines.  The core stage was secured to a giant test stand at Stennis Space Center, Mississippi for the test.

SLS core stage in the B-2 test stand at Stennis Space Center, MS just prior to the second hot fire test, March 18, 2021. Screengrab.

The RS-25 engines are left over from the space shuttle program and all flew into space before the shuttle program was terminated in 2011. Only three were needed for the reusable space shuttle orbiter, but SLS needs four.  The January test was the first time four were fired at the same time. Today was the second. All apparently went well.

Second SLS hot fire test underway at Stennis Space Center, MS, March 18, 2021. Screengrab.

During a post-test press conference, NASA SLS Program Manager John Honeycutt said all the data so far shows everything was nominal. He gave the core stage an A+ and praised SLS Stages Manager Julie Bassler, the Boeing/Rocketdyne team, and the team at Stennis Space Center for a job well done.

Praise also came from members of Congress, including Sen. Richard Shelby (R-AL), one of the driving forces behind SLS. The program is managed at NASA’s Marshall Space Flight Center (MSFC) in Huntsville, AL.  Shelby, who chaired the Senate Appropriations Committee when Republicans controlled the Senate and now is Vice Chairman, is a powerful champion for the program.

Rep. Robert Aderholt (R-AL), who represents a district near MSFC and is the top Republican on the House appropriations subcommittee that funds NASA, called it exciting.

Sen. Roger Wicker (R-MS) who represents Stennis Space Center retweeted a congratulatory tweet from Republicans on the Senate Commerce Committee, which oversees NASA. Wicker chaired the committee when the Senate was under Republican control and now is its top Republican.

Several other members of Congress from both parties also offered congratulations, including Rep. Eddie Bernice Johnson (D-TX) and Don Beyer (D-VA), the chairs of the House Science, Space, and Technology Committee and its space subcommittee, who issued a joint press release.

NASA has decided not to reuse the shuttle-era engines anymore, so their next journey to space on the first SLS test flight, Artemis I, will be their last.  Twelve more engines remaining from the shuttle program will power the next three SLS missions. Aerojet Rocketdyne has an almost $2 billion contract with NASA to build 18 new RS-25s for the future.

Artist’s illustration of SLS on its launch pad. The core stage is orange. Credit: NASA

It will take about a month for engineers to get the core stage ready for shipment to Kennedy Space Center, FL. Once there  it will be integrated with the other SLS components, including two 5-segment Solid Rocket Boosters from Northrop Grumman, in preparation for Artemis I, an uncrewed test flight of SLS with an Orion spacecraft around the Moon.

The launch is about 3 years late and the agency has been hoping to get it off the pad this year.  Acting NASA Administrator Steve Jurczyk told earlier this week that the agency will know in a few weeks whether it has a “reasonable shot” to launch in November, the current plan, “or if we need to move to the right a little bit.”

The first test launch with a crew, Artemis II, is planned for 2023.  Under the Trump Administration’s plan, Artemis III would launch in 2024 and take astronauts back to the Moon for the first time since Apollo 17 in 1972.  The Biden Administration supports the Artemis program, but has not yet indicated what schedule it has in mind.

The 2024 date was chosen by the Trump Administration because it would have been the end of a second Trump term if he had been reelected, but was considered unrealistic for technical and budgetary reasons by almost everyone in the space community.

During the post-test press conference, Jurczyk said NASA has gotten “good support from the Biden Administration really across the board” not just for Artemis, but NASA’s broader portfolio including climate change, reducing the environmental impact of aviation, and inspiring students in STEM education. “I am really excited about the support we’ve gotten from the Biden Administration.”

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