NASA officials are more confident that the Saturday launch attempt of its Artemis I mission to the moon will be successful after poring over data that led to Monday’s scrub, while weather may cooperate as well.
In fact, Monday’s scrub at Florida's Kennedy Space Center might have been unnecessary after NASA discovered the main reason for it was inaccurate sensor readings. Although there were several issues during the countdown that caused stress on the launch teams, the false reading was that one of the four RS-25 engines at the base of the Space Launch System rocket core stage had not cooled enough for a safe launch.
“We had some sensors that didn’t tell us what we thought,” said NASA SLS chief engineer John Blevins during a mission update Thursday. “We did the right thing by standing down with that uncertainty on Monday but we have confirmed that we did have good flow through those engines. We know we can chill those engines. We’re ready to proceed.”
Blevins said those sensors, which are unreachable on the launch pad, will be ignored for Saturday’s attempt. The two-hour launch window for liftoff opens at 2:17 p.m. with a backup launch attempt available on Monday during a 90-minute window that opens at 5:12 p.m.
Weather for Saturday’s attempt, though, is looking better than earlier forecasts, with the Space Launch Delta 45 weather squadron giving it a 60% chance for good conditions at the opening of the window, but improving later in the afternoon.
“I do expect to make some no-go calls at some point,” said SLD 45 weather officer Melody Lovin on Friday. “However, as that East Coast sea breeze drifts farther inland, we do expect clearing on the backside of that, and that is the reason why we are turning the forecast to more of an 80% favorability at the end of the launch window.”
If it delays, the Monday forecast odds are set to 70%.
“I do not expect weather to be a showstopper by any means for either launch window,” she said.
Crowds on the Space Coast to watch the launch could approach 400,000, according to the Brevard County Emergency Operations Center with traffic delays expected on either side of the attempt. That would more than double the estimated crowd that left town disappointed on Monday.
The Monday scrub in some ways was due to issues faced during tanking that then pressed NASA teams for time. That included detection of a potential hydrogen leak along with weather that forced holds in the countdown. Later in the count, the test of what is known as the bleed system of super-cooled liquid hydrogen into the engines proved too complicated to work around in the time remaining before liftoff.
While mission managers have addressed the possible hydrogen leak and determined the engines did in fact cool during the bleed test despite the sensor readings, more time in the countdown clock has been added to better troubleshoot issues that may arise.
“So this is a test flight, right? And so while I feel very good about our procedures, when you look the team in the eye, they’re ready,” said Jeremy Parsons, deputy manager for NASA’s Exploration Ground Systems.
The goal if the rocket launches Saturday is to send the SLS rocket topped with the uncrewed Orion capsule on a 38-day mission to orbit the moon several times before it heads back for a splashdown on Earth in the Pacific Ocean on Oct. 11.
The core stage combined with its two solid rocket boosters will produce 8.8 million pounds of thrust on liftoff making SLS the most powerful rocket to launch from the Earth besting the Saturn V rockets of the Apollo program.
The mission looks to push the extremes for Orion sending it on a much longer mission than if it were traveling with humans, and making sure its heat shield holds up as it becomes the fastest human-rated spacecraft to re-enter Earth’s atmosphere at 24,500 mph producing temperatures near 5,000 degrees Fahrenheit.
While no humans are along for the ride, three mannequins are strapped into Orion to test out a new space survival suit as well as a radiation protection jacket.
If all goes well, the mission will pave the way for Artemis II in 2024 that would take four astronauts on an orbital mission of the moon. That would be followed by Artemis III, which aims to return humans including the first woman to the lunar surface for the first time since Apollo 17 in 1972.
Mission managers, though, warn that despite confidence that they have a handle on the issues that popped up Monday, this weekend’s attempt is not without risk. Artemis mission manager Mike Sarafin said there are 489 launch commit criteria to run through before liftoff.
“Things like weather and a whole host of other criteria are are part of our launch commit, so we will wait and see what the conditions are and we will go when when the vehicle is ready and we understand the risk posture,” he said.
But the countdown clock was reset to 45 hours until liftoff and counting on Thursday and teams performed power and leak tests into Friday with tanking scheduled to begin around 5:30 a.m. Saturday.
“There’s no guarantee that we’re going to get off on Saturday,” Sarafin said. “But we’re going to try, and the technical teams have put in a tremendous amount of work in a very short amount of time to get us here.”
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To the moon
What: Artemis I rocket launch on 37-day mission to the moon
When: Saturday, during 2:17-4:17 p.m. window; backup window Monday, during 5:12-6:42 p.m window
Where: Launch Pad 39-B at Kennedy Space Center
Weather: 60-80% chance for good conditions Saturday
Where to watch: Live coverage begins on NASA TV at nasa.gov/live and its social media channels at 5:45 a.m.
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