SLs core stage at Stennis
The core stage of the first SLS being installed on a test stand at the Stennis Space Center earlier this year. Work on the SLS there is suspended as the center moved to Stage 4 of NASA's pandemic response plan. Credit: NASA/SSC

WASHINGTON — NASA and Boeing are on track to perform a major static-fire test of the core stage of the Space Launch System in October, a key milestone ahead of a first launch in late 2021.

Speaking at the American Astronautical Society’s Glenn Memorial Symposium July 15, John Shannon, Boeing vice president and program manager for SLS, said crews working testing the SLS core stage at the Stennis Space Center have run into “no issues” so far during a series of tests collectively known as the Green Run.

The core stage, built for the Artemis 1 mission, arrived at Stennis in January for the Green Run, which will culminate with a full-duration static-fire test of the stage’s four RS-25 engines. However, the coronavirus pandemic interrupted that work in March for about two months.

Three of eight Green Run tests have been completed, including applying forces to the core stage to simulate launch conditions, powering on the stage’s avionics and testing the systems that would shut down the stage if there’s a problem during testing. Shannon said work is underway on the fourth test, checking components of the rocket’s main propulsion system.

“So far the design has held up really well,” he said. “We’ve had no issues with power-ups or checks.”

After the ongoing propulsion system checks, workers will test the rocket’s thrust vector control and other hydraulic systems, followed by a practice countdown. NASA will then be ready for the final two major tests, a “wet dress rehearsal” where the core stage is loaded with liquid hydrogen and liquid oxygen propellants, and then the eight-minute static-fire test.

“We’re looking forward to the wet dress rehearsal, where we put cryogenics in the vehicle, in September, and then the hot fire in October,” Shannon said.

The Green Run test campaign is on the critical path for the first SLS launch. Most of the other components needed for the Artemis 1 mission are already complete. Northrop Grumman delivered the 10 solid rocket booster segments to the Kennedy Space Center last month. The Interim Cryogenic Propulsion Stage upper stage has been in storage at KSC for some time, and the Orion spacecraft that will be launched on that uncrewed test flight is also essentially complete.

NASA has not set a new target launch date for the Artemis 1 mission. In May, Tom Whitmeyer, NASA assistant deputy associate administrator, told an advisory committee the launch date would likely be in late 2021, the latest in a series of delays, but the agency has not announced a more specific date yet.

“I would say that 2021 is a very reasonable date for Artemis 1,” Shannon said when asked later in the panel session about when the mission would fly. “It seems like ’21 is a very reasonable goal to set and it’s very achievable.” He did not specify when in 2021 Artemis 1 would launch.

That would be followed by the first crewed Orion mission, Artemis 2, which NASA has recently suggested will now launch in 2023. Artemis 3, the first lunar landing mission, would then launch the following year to meet the administration’s deadline of landing humans on the moon by the end of 2024.

Shannon said that production is already underway on elements of the SLS vehicles needed for those next two Artemis missions, and did not expect the SLS to be an obstacle to a 2024 landing. A bigger challenge, he suggested, is development of the lander needed for the Artemis 3 mission.

Earlier in the online conference, NASA Administrator Jim Bridenstine said he was still optimistic that the agency’s Human Landing System program will get the funding it needs. NASA requested $3.3 billion for the program to support lander development, but a spending bill approved by House appropriators July 14 provides less than a fifth of that amount.

“I think the odds are good” of getting that full funding, he argued. He expected the Senate to provide more funding in its appropriations bill, with the higher amount winning out when the House and Senate hammer out their differences in conference. “I think we will have the ability to get the resources that we need to land on the moon in 2024.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...