Monday (June 20) was a big day for NASA’s Artemis 1 mission.
The agency’s massive moon rocket, the Space launch system (SLS), ended a 50+ hour launch simulation known as a “wet rehearsal” on Monday night (June 20). After several failed attempts in April, mission team members were able to fully fuel the SLS for the first time on Monday, wrapping up a series of crucial pre-launch testing.
It was a major milestone for the Artemis 1 lunar mission, but there were some problems along the way.
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Ground teams 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 just as they would if they were preparing for an actual launch.
SLS is the backbone of NASA Artemis Programa continuation of the new Apollo era that the space agency hopes will help establish a permanent human presence in the moon. And with a new moon comes a new moon rocket. The SLS has never flown, and the recent wet trial was supposed to be its last hurdle. But whether Artemis 1 is really ready to fly now remains unclear.
Monday’s activities mainly focused on filling the rocket’s cryogenic fuel tanks. The two-stage SLS uses liquid hydrogen (LH2) and liquid oxygen (LOX) as hypergolic thrusters. Three attempts to fuel the rocket during a previous wet suit attempt in April were halted when operators encountered technical problemsincluding a hydrogen leak atop the Artemis 1 mobile launch pad (MLP).
These issues were addressed inside KSC’s Vehicle Assembly Building (VAB) last month, but controllers on Monday found another hydrogen leak while running the wet dress on the launch pad. This new leak, however, appeared at a “quick disconnect” – a point where the supply cables connecting the SLS to the MLP are designed to be separated during launch.
This new leak affected the process on Monday. The technicians’ efforts to resolve the issue were unsuccessful and their work delayed the count by three hours. But with the SLS fully stocked, NASA officials made the decision to forward a software patch that would allow them to continue the simulated countdown anyway.
The patch allowed the ground launch sequencer to basically bypass automatic checks that would have detected the leak, but the SLS’s onboard flight systems could not pass the same failsafe bypass. As planned, the terminal count continued until the T-33 seconds mark, at which point the ground computers hand over flight control to the SLS systems.
The count was finally stopped at T-29 seconds. NASA had hoped to reduce the clock down to T-9 seconds as originally planned, but is considering the wet trial to be a big success regardless.
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“I would say we’re in the 90th percentile,” Mike Sarafin, NASA’s Artemis mission manager, said during a call with reporters Tuesday (June 21).
“Terminal counting is a very dynamic time,” explained Charlie Blackwell-Thompson, Artemis’ launch director with KSC’s Earth Exploration Systems Program.
There are “a lot of time-critical events that happen in the terminal count, which are verified both in the flight software and on the ground and in the interaction between the two,” he added.
Citing the quick-disconnect leak as the only major hiccup during Monday’s tank, Blackwell-Thompson and other NASA representatives on the call agreed that the wet dress was “extremely soft.”
Now, agency officials need to determine whether that wet dress was good enough. The leak prevented the count from reaching the T-9’s second target to abort the wet dress launch, but that doesn’t mean NASA will have to do the wet test again before deciding to launch the Artemis 1 mission, which will send a Gutted Orion. on a journey of approximately one month around the moon. And by Tuesday’s call, nothing had been decided.
“There are some things we don’t get in the terminal count,” Blackwell-Thompson said. “Let’s see what they are. Let’s see what that means for 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’ve accomplished, see what additional work might be needed and take a look at the [quick disconnect]”, added Sarafin during Tuesday’s call, noting that since the NASA operators’ long day on Monday, there was still not much work to do to analyze any of the test data.
NASA officials on the call were optimistic about the way forward, though not committing to what lies ahead for Artemis 1 in the immediate future. On the call, there was a shared confidence that a clearer path would emerge in a few days, after the team had a chance to examine Artemis 1’s pile and wet dress data.
“We’re going to take all of yesterday’s data and put it in the next time we load this vehicle,” Blackwell-Thompson said. “I’m sure it will be as smooth as the main stage was yesterday.”
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