After three previous discontinued trials, NASA has successfully launched its new massive deep space rocket, the Space Launch System, for the first time on Monday – completing a critical phase before the vehicle’s first flight. However, there was a shadow over the achievement. The refueling was part of a complex dress rehearsal that ended 20 seconds earlier than planned by NASA, and it is unclear whether the agency has received all the data and practice needed to continue with the rocket’s debut launch.
The space launch system, or SLS, is a key part of NASA’s Artemis flagship program – a complex job of sending the first woman and the first colored man to the surface of the moon. But first, the SLS must actually fly, and before that happens, NASA wanted to go through all the complex steps that lead to an actual launch – except for the part where the rocket takes off.
As the SLS stands on its launch pad at the Kennedy Space Center in Florida, NASA engineers and flight supervisors filled the vehicle with their ultra-cold fuels on Monday, just as they would on the day of the launch. With all SLS tanks full, the flight crew counted down to a simulated take-off time, with a plan to stop the countdown to approximately T-minus 9 seconds. Instead, the team stopped the countdown at T-minus 29 seconds due to a hydrogen leak. NASA says it has managed to meet most of its test objectives, basically refueling the vehicle – but there are still a handful that they failed to reach with a premature break.
“I would say that most of our goals have been achieved.
“I would say most of our goals have been achieved,” said Charlie Blackwell-Thompson, director of the Artemis launch at NASA, during a post-test press conference. “There may have been small pieces within that main goal that we’ve come to a little bit of.”
NASA has tried this dress rehearsal three times before, and all of those experiments are over before flight controllers can fully refuel the rocket. After the third failed attempt, NASA drove the SLS into the agency’s massive vehicle assembly building to make various repairs and upgrades before dropping the rocket back on the site on June 6.
Three of the rehearsal’s biggest goals include a demonstration that the flight crew could refuel the vehicle, stop the countdown and then drain the SLS – all of which took place on Monday. In addition, NASA managed to enter the terminal countdown, the last phase of the countdown, which begins T-minus 10 minutes before launch.
NASA / Ben Smegelski
One of the big things they failed to test was trying to recycle. Initially, the team planned to go down to T-minus 33 seconds, stop the countdown and then return to T-minus 10 minutes. This aim was to simulate an unexpected delay on the start day and an attempt to retry, which can sometimes happen. Then the team would reach T-minus 9.3 seconds – just before the sequence began to ignite the main engines at the base of the rocket.
Plans changed during the test. The simulated take-off was delayed for hours due to a number of problems that flight supervisors worked on throughout the day, including a hydrogen leak. In the end, the flight controllers chose to skip the stop and turn at T-minus 33 seconds and just continue to T-minus 9.3 seconds, according to CBS. However, they knew that the hydrogen leak was likely to disrupt the flight computers before reaching this final countdown.
“We will decide which is the best way forward.”
During a press conference after the test, NASA officials stressed that most of the goals of the dress rehearsal have been met. “I’d say we’re in the 90th percentile in terms of, you know, where we need to be in general,” said Mike Sarafin, head of NASA’s Artemis mission. But they were unclear about the elements that had not been completed. One of the goals they did not achieve was to demonstrate something known as “flow leakage” – a way to maintain proper fuel temperatures – due to hydrogen leakage. There was also old hardware for solid rocket accelerators that didn’t have a chance to fire as planned.
NASA is now saying it is reviewing the data it has collected and will determine the next steps. “I think we’ll take a few days and get through this, and then we’ll decide which is the best way forward,” said Tom Whitmeier, NASA’s deputy administrator for common research systems. The agency may choose to do another type of refueling test, and NASA’s Jim Free, NASA’s associate administrator for research systems development, said before the experiment that NASA wanted an in-depth pre-flight test. “This is the first time we have flown with this vehicle and I think we need to understand everything we can before we commit to launching,” Free said last week. But Whitmeier noted that there was a “relative risk of continuing to exercise the pad hardware.”
As for how this could affect the timeline for the first SLS flight, NASA will not say. SLS is expected to make its debut during a flight called Artemis I, which will see the rocket launch an empty capsule of the crew, called Orion, around the moon during a week-long voyage. Prior to this dress rehearsal, NASA noted that the earliest possible launch attempt would be during a window that opened in late August. Now, with this test, NASA does not set any hard dates. “I don’t think we know yet,” Whitmeyer said. “We really need to sit down and do everything we just talked about: look at the goals, see what we’ve achieved, and see what extra work may be needed.”
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