NASA’s Aerospace Safety Advisory Panel (ASAP) reiterated today that it views the Green Run test for the Space Launch System (SLS) as “critical” from a safety and mission assurance standpoint. NASA continues to debate whether the test can be skipped to speed up the program and get the first launch off the pad in 2020. The head of NASA’s human spaceflight program said last week that NASA’s internal recommendation is to do the test, but a decision has not been made.

NASA is developing the Saturn V-class SLS to take astronauts beyond low Earth orbit for the first time since the Apollo program. A spacecraft, Orion, is also under development to accommodate the crew. The Trump Administration wants to put astronauts back on the surface of the Moon by 2024 using SLS/Orion.

Boeing is the prime contractor for SLS. Lockheed Martin is the prime contractor for Orion.

The SLS Green Run test will take place at NASA’s Stennis Space Center in Mississippi, the only place that has a test stand large enough to hold the core stage outfitted with all four of its RS-25 engines. The plan is to fire all four engines for 8 minutes, the full duration they would fire during an actual launch.

It will take several months to get the core stage ready for the test once it arrives at Stennis, so the test is time consuming and expensive, but the resulting data will reduce the technical risk of a problem cropping up during an actual launch.

Indications that NASA was considering skipping the test and relying instead of data from a much shorter (seconds instead of minutes) engine firing on the launch pad at Kennedy Space Center began circulating in March after Boeing informed NASA that the first flight would be delayed again. Originally promised for November 2018, it already had slipped to a December 2019-June 2020 timeframe and now was slipping into 2021.

Initially designated Exploration Mission-1 (EM-1), the launch is now called Artemis-1. NASA recently named the program to return astronauts to the lunar surface by 2024 as Artemis, the twin sister of Apollo in Greek mythology.

No one will be aboard Artemis-1. It is a test flight. The first launch with a crew is the next one, Artemis-2.

ASAP was created by Congress following the 1967 Apollo 204 fire that took the lives of astronauts Virgil “Gus” Grissom, Ed White and Roger Chaffee. It is a NASA advisory panel, but because of its origins, reports both to the NASA Administrator and Congress. It advises NASA on anything affecting safety at the agency. Each quarter it holds a public session where panel members report on what they learned in fact finding meetings with NASA and others.

In April, ASAP emphatically urged NASA not to skip the Green Run test. Panel chair Patricia Sanders said “I cannot emphasize more strongly that we advise NASA to retain this test in the program.”

That message was reiterated today. David West called the Green Run a “critical milestone for safety and mission assurance” that should be retained. He also highlighted the need for the Artemis-1 flight itself to address all the test objectives originally planned.

“[The] panel would like to reiterate again its firm belief that the Green Run, which is a full scale, fully instrumented test of the propulsion system, is a critical safety and mission assurance milestone for the program and should be retained. In addition, as the panel has previously commented, it is really important that the program continue to ensure that the Artemis-1 mission incorporates those elements of test that are required to retire risk prior to the first crewed mission on Artemis-2. — ASAP Member David West

He added that one of the changes between Artemis-1 and Artemis-2 that the panel will be investigating soon is the design and qualification of the Orion capsule’s side hatch.

Last week, Bill Gerstenmaier, the head of NASA’s human spaceflight program, told the NASA Advisory Council (NAC) that NASA’s internal recommendation is do to the Green Run test, but a final decision has not been made. Considerable analysis has been done that shows it “potentially” could be skipped, but based on his experience, these tests are done not because of what needs to be verified, but because of the “unknown unknowns that come about.” Doing the test probably would mean the Artemis-1 launch would not happen until early 2021, however. Gerstenmaier told NAC he expects a decision by the end of this month.

Sanders and George Nield made the point today that having a firm date like 2024 for a Moon landing can be a positive because it focuses attention, but it is important to avoid “launch fever” and not make decisions that undermine mission assurance and safety.

Another message from ASAP is that the goal of getting back to the Moon by 2024 should not distract from ensuring the safety of NASA’s other programs, like commercial crew. Boeing is on track to conduct its pad abort test and uncrewed and crewed test flights this year. SpaceX continues to investigate the April “anomaly” that destroyed a Crew Dragon capsule. The root cause remains unknown, but Susan Helms praised SpaceX for taking advantage of the investigation to make improvements to the Dragon’s design even though it is not clear they are related to the anomaly. The fact that SpaceX is “adaptable and agile on design changes … is a positive aspect of their culture.”