WASHINGTON — An uncrewed test of NASA’s Space Launch System and Orion spacecraft moved a step closer to launch with the completion of a flight readiness review Aug. 22.
NASA officials said late Aug. 22 that the review confirmed plans for a launch of the Artemis 1 mission from Kennedy Space Center’s Launch Complex 39B as soon as 8:33 a.m. Eastern Aug. 29, at the beginning of a two-hour window. A second two-hour window is available Sept. 2, and a 90-minute window Sept. 5.
“We had no exceptions today. We actually had no actions coming out of the review and we had no dissenting opinions,” Jim Free, NASA associate administrator for exploration systems development, said at a briefing after the review.
There is still some “open work” to do on the SLS and Orion spacecraft before launch, said Mike Sarafin, Artemis mission manager at NASA. Some of that is planned work to prepare the vehicles for launch, “largely things that we have a path to close before we go fly.”
One issue that won’t be checked until the final stages of the countdown is a step called the “hydrogen kickstart” to thermally condition the engines. That could not be tested during the series of wet dress rehearsals of the vehicle in April and June because a leak in a hydrogen bleed line detected in the final rehearsal in June.
Sarafin and Charlie Blackwell-Thompson, Artemis launch director, said there is a plan to test that step during a “quiescent” phase in the countdown a few hours before launch once the core stage’s liquid hydrogen tank is filled. “We believe that we have taken all the actions to correct that problem,” Blackwell-Thompson said, but won’t know for certain until the test at the pad.
“If we do not successfully demonstrate that,” Sarafin said, “we are not going to launch that day.”
A launch on Aug. 29 would start what is scheduled to be a 42-day mission for the Orion spacecraft. The SLS’s upper stage will place the spacecraft on a trajectory to the moon, called translunar injection (TLI), less than two hours after liftoff. Orion will fly by the moon five days later, maneuvering into a distant retrograde orbit around the moon. After spending two weeks in that orbit, the spacecraft will maneuver back to the moon, performing another powered flyby to bring it back to Earth, splashing down off coast of San Diego, California Oct. 10.
The six-week mission is a stress test of sorts of the spacecraft. Howard Hu, NASA Orion program manager, noted that Orion is designed to support a four-person crew for three weeks. “This mission allows us to push a lot of capability,” he said. “The long-class mission we’re talking about, 42 days, will allow us to stress a lot of systems.”
“Going 42 days puts a lot more stress on those systems, plus the environment it’s in — longer exposure to radiation, longer exposure to micrometeoroid hits — means we’re going to learn a lot from this test flight,” said Bob Cabana, NASA associate administrator. “We’re stressing it beyond what it is designed for and we’ll see what we learn.”
Cabana and others at the briefing emphasized that Artemis 1 was a test flight. “It’s not without risk,” he said. That includes scenarios, he said, where Orion is not able to complete the planned mission and returns early.
NASA, though, will push to at least send Orion towards the moon to enable the mission’s top objective, testing the spacecraft’s heat shield at lunar reentry velocities of about 40,000 kilometers per hour. That includes pressing ahead with TLI even if there are issues with the spacecraft, like a solar panel that doesn’t properly deploy immediately after launch.
“We have a lean-forward strategy to get our high-priority objective, which is to demonstrate the heat shield at lunar reentry conditions,” said Sarafin. “We’re going to press to the point of translunar injection unless we’re sure we’re going to lose the vehicle.”
“We would be go on this flight for conditions that we would normally be no-go for on a crewed flight in the interest of crew safety, because we want to buy down risk,” he added.
