NASA’s Aerospace Safety Advisory Panel (ASAP) emphatically urged NASA today not to skip the Green Run test planned for the Space Launch System (SLS). NASA is considering that option in order to meet the Trump Administration’s recent directive to return astronauts to the lunar surface by 2024, four years earlier than NASA was planning. The directive was issued just after Boeing notified NASA that the first SLS flight would slip from 2020 to 2021. NASA is trying to figure out how to get SLS back on track.

Boeing is the prime contractor for SLS, a rocket that in its final form will be able to launch as much as the Apollo-era Saturn V. The initial version is less capable than that, but will be able to send the Orion capsule with a crew of four to lunar orbit. The first SLS launch, Exploration Mission-1 (EM-1), is an uncrewed test. The date has slipped several times. Most recently it was scheduled for no later than June 2020, but Boeing told NASA last month that it will be delayed into 2021.

Instead of accepting the delay, Pence traveled to NASA’s Marshall Space Flight Center in Huntsville, AL, where the program is managed, on March 26 and announced the Moon-by-2024 goal. He warned that NASA is not committed to “any one contractor” and if the “current contractor can’t meet this objective, then we’ll find ones that can.” He was just as blunt with NASA. If NASA cannot meet the objective, then NASA must change, not the objective.

Even before the March 26 speech, NASA had begun looking at alternatives to SLS for the EM-1 test flight — which would mean testing only Orion, not SLS — but concluded there were no viable options that could meet the 2020 date.

NASA then began assessing how to get SLS back on schedule. Skipping tests could do that, but it increases risk.

One test that will consume several months of schedule is the all-up “Green Run” test at Stennis Space Center in Mississippi. The SLS core stage will be put on a test stand and all four of its RS-25 engines will fire for 8 minutes, the same length of time they will have to perform for an actual launch.

NASA is considering replacing that 8-minute test with a significantly shorter test when the rocket is already on the launch pad at Kennedy Space Center.

ASAP made it clear they think that’s a very bad idea.

There is no other test approach that will gather the critical full scale integrated propulsion system operational data required to ensure safe operation. Shorter duration engine firing at the launch pad will not achieve an understanding of the operational margins and could result in severe consequences conducted in a much less controlled environment than Stennis if the margins are exceeded. I cannot emphasize more strongly that we advise NASA to retain this test in the program.” – ASAP Chair Patricia Sanders

She listed other tests and milestones that also are critical, concluding with the admonition that “this is no time to jeopardize the program by introducing unwarranted risk.”

As for the Moon 2024 goal itself, she stressed the importance of setting “achievable schedules” because unrealistic schedules can result in “bad decisions” and damage morale. The key is to not lose sight of the longer term goals and use near-term flights to buy down risk for future human exploration.

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.