NASA hopeful SLS Green Run test remains on schedule

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WASHINGTON — Despite a weather-related pause in testing work, NASA still hopes to complete the Green Run test of the Space Launch System core stage in October, keeping its first launch on track for late next year.

NASA said Aug. 24 that it suspended work on the SLS core stage at the Stennis Space Center in Mississippi because of concerns about two tropical storms, Laura and Marco, in the Gulf of Mexico. While Marco has since dissipated, Laura is projected to strengthen into a major hurricane and make landfall Aug. 27 near the Texas-Louisiana border. Gusty winds and heavy rain could still extend east toward Stennis.

At the time NASA halted work, teams were working on tests of the thrust vector controls on the stage and performing leak checks, Kathy Lueders, NASA associate administrator for human exploration and operations, said in an Aug. 25 presentation at the American Institute of Aeronautics and Astronautics (AIAA) Propulsion and Energy conference online. That work was leading up to the last two major tests of the overall Green Run campaign, a wet dress rehearsal where the stage is loaded with liquid hydrogen and liquid oxygen propellants, followed by a full-duration static-fire test of the stage.

“I’m still hopeful we’ll do wet dress in September,” she said. “If we get through wet dress in September, we’re in a good spot to be able to do our hot fire by the end of October.”

If that schedule holds, Lueders said the core stage would then arrive at the Kennedy Space Center in Florida in January for a launch of the Artemis-1 mission currently expected in November 2021. In a separate conference webinar Aug. 24, Lueders said there was “some margin” in that schedule leading up to the Artemis-1 launch.

Lueders said in her presentation that another issue for SLS is the ability of the supplier base to meet NASA’s needs as it seeks to increase production of the heavy-lift rocket, a situation that has only gotten worse during the pandemic. “We’re really having a hard time with parts of our supplier base. It was tough six months ago, but it’s really, really tough now.”

She attributed those supply chain issues to the growing demand for aerospace components given launch vehicle and spacecraft projects by several companies. “It’s a blessing and a curse having lots of vehicles getting ready at the same time,” she said. “It’s been a big pull on our supplier base.”

Another major challenge facing Lueders is the Human Landing System (HLS) program to develop lunar landers for the Artemis missions. From a technical standpoint, the work is going well with Blue Origin, Dynetics and SpaceX, which won HLS awards in April. “Our Human Landing System teams have hit every single one of their milestones” so far, she said.

A bigger challenge may be funding, given that the House provided only 20% of NASA’s requested $3.3 billion for HLS in its version of a fiscal year 2021 spending bill approved last month. Senate appropriators are expected to work on their version of the bill in September.

“The big challenge is going to be to see where we end up with our final appropriations, and then we’ll have to make some decisions,” Lueders said in the Aug. 24 webinar, acknowledging that getting only a fraction of their requested funding “makes it tough.”

For now, she said NASA was going to focus on the ongoing HLS work, and the proposals those companies will submit to continue development when the current HLS awards end early next year. “We’ll need to make some decisions when we have a better idea of how much funding we have,” he said.

Dealing with problems, though, is nothing new for the Artemis program. Lueders noted that the latest pause in core stage testing came after a hiatus this spring because of the coronavirus pandemic. Technical issues caused far more extensive problems earlier in the vehicle’s development. “I tell people, ‘Let me know when the locusts show up.’”