Monday (June 20) was a big day for NASA’s Artemis 1 mission.
The agency’s huge new moon rocket, the Space Launch System (SLS), completed a more than 50-hour launch simulation known as a “wet dress rehearsal” on Monday night (June 20). After several unsuccessful attempts in April, the mission team members succeeded full fuel SLS for the first time on Monday, concludes a series of crucial pre-launch tests.
It was a big milestone too Artemis 1 moon mission, but there were some snags along the way.
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Ground crews at NASA’s Kennedy Space Center (KSC) in Florida spent the weekend reviewing procedures and checklists for Artemis 1’s SLS, Orion capsule and ground systems in the same way they would if they were preparing for an actual launch.
SLS is the backbone of NASA’s The Artemis programa new sequel to Apollo that the space agency hopes will help establish a permanent human presence on the moon. And with a new lunar shot comes a new lunar rocket. SLS has never flown, and the recent wet dress rehearsal should be the last hurdle. But whether Artemis 1 is actually ready to fly now is not yet clear.
Monday’s activities focused primarily on filling the rocket’s cryogenic fuel tanks. Two-stage SLS uses liquid hydrogen (LH2) and liquid oxygen (LOX) as hypergolic propellants. Three attempts to burn the rocket during an earlier attempt at a wet dress in April were suspended when the operators encountered technical problemsincluding a hydrogen leak high in the Artemis 1 stack’s mobile launch platform (MLP).
These issues were addressed inside KSC’s Vehicle Assembly Building (VAB) over the past month, but inspectors on Monday got a new hydrogen leak while driving the wet dress at the launch pad. However, this new leak appeared in a “quick disconnect” – a point where the fuel cables that connect the SLS to the MLP are designed to be disconnected during launch.
This new leak affected the proceedings on Monday. The technicians’ attempt to troubleshoot the problem was unsuccessful, and their work pushed the count back three hours. But with the SLS full tank, NASA officials made the decision to schedule a software update that would allow them to continue the simulated countdown anyway.
The patch allowed the ground-start sequencer to skip the automatic checks that would have detected the leak, but the SLS onboard flight systems failed to undergo the same fail-safe bypass. As planned, the terminal count continued through the T-33 second mark, at which time the ground computers leave flight control to SLS’s systems.
The count was finally stopped at T-29 seconds. NASA had hoped to run the clock all the way down to T-9 seconds, as originally planned, but considers the wet general test to be largely a success anyway.
Photos: NASA’s new Space Launch System mega rocket
“I want to say that we are in the 90th percentile,” Mike Sarafin, Artemis’ mission leader at NASA, said in an interview with reporters on Tuesday (June 21).
“Terminal counting is a very dynamic time,” explained Charlie Blackwell-Thompson, Artemis’ launch director with the Exploration Ground Systems Program at KSC.
There are “many time-critical events that take place in the terminal count, which are checked both in the flight software and on the ground, and in the interaction between the two,” she added.
Blackwell-Thompson and other NASA representatives at the conversation were referred to the fact that the leak was the only major hiccup during Monday’s refueling, and agreed that the wet dress was “extremely slippery.”
Now the agency’s officials have to decide if this wet dress was good enough. The leak prevented the count from reaching the T-9 second target for interrupting the launch of the wet dress, but that does not mean NASA will have to retake the dress rehearsal before deciding to launch the Artemis 1 mission, which will send an unmanned Orion on a about a month-long journey around the moon. And at Tuesday’s talk, nothing was decided.
“There are a few things we did not get in terminal numbers,” said Blackwell-Thompson. “We’ll look at what they are. We’ll look at what it means to us, if there are ways to test them, and then we’ll come back and make a recommendation.”
We really need to sit down and … look at what we have achieved, see what extra work may be required, and take a look at [quick disconnect]”, Sarafin added during Tuesday’s conversation, pointing out that since the NASA operators’ long day on Monday, not much work had yet been done to analyze any of the test data.
NASA officials at the call were optimistic about the way forward, although they were non-committal about what’s next for Artemis 1 in the immediate future. During the conversation, there was a shared confidence that a clearer way forward would emerge in a few days, after the team had a chance to examine the Artemis 1 stack and data from the wet dress.
“We’ll take all the data from yesterday and roll it in the next time we load this vehicle,” said Blackwell-Thompson. “I’m sure it’s going to be as smooth as the core scene went yesterday.”
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