Trevor Malman
NASA tried three times in April to complete a critical power test of the large Space Launch System rocket. And three times, due to about half a dozen technical problems, the space service failed.
And so NASA made the difficult decision to throw the big rocket back into the Vehicle Assembly Building for repairs, adding a few months of delays to a program that had already been delayed for years. Following the completion of this work in early June, NASA dropped the SLS rocket and Orion spacecraft back on the launch pad for a fourth attempt.
The painful decision proved to be the right one. Over 14 hours on Monday, NASA largely completed this power test, loading hundreds of thousands of gallons of liquid oxygen and hydrogen into the first and second stages of the SLS rocket.
“It was a tiring day for the team, but I think it was a very successful day for the team,” said Charlie Blackwell-Thompson, Artemis’ starting manager.
She and other NASA officials spoke to a news conference Tuesday to discuss the results of the fourth “liquid clothing test” test, which aims to resolve the countdown to launching the rocket before launch day. To this extent, the test seemed to work to a great extent. NASA arrived within T-29 seconds of launch during the test, close to its target T-9.3 seconds, before completing the test shortly before the four main rocket engines ignited.
During the teleconference, NASA officials declined to answer specific questions about whether a fifth test would be needed – to reduce the countdown to T-9.3 seconds – or when the rocket might be ready for launch. his first launch. Citing a desire to review more data, officials said they expected to provide this information in a few more days. From their comments, however, it appeared that officials may be leaning towards a fifth test.
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A handful of technical problems occurred during Monday’s test, the most significant of which was a hydrogen leak at a rapid disconnection at the bottom of the mobile launch tower that supports the SLS rocket while refueling. This 4-inch hydrogen line is one of many released by the rocket shortly before launch and connected to the tower’s tail web.
NASA could not solve the problem with a seal leak during the last part of Monday’s test, so it chose to cover the leak from the ground launch sequencer, the ground computer that controls most of the countdown. This poses no risk to the rocket during the test, but should be corrected before the actual launch.
With this piece of coverage, NASA’s launch team was able to reach from T-10 minutes to T-29 seconds and demonstrate the ability not only to fill the SLS rocket but also to maintain its fuel tanks. When the ground launch program was delivered to the rocket embedded computer for the last part of the countdown, the flight computer automatically terminated the count.
NASA executives liked what they saw. “This is the first time we are in a completely cryogenic environment at both the basic and advanced stages,” said Blackwell-Thompson. “Counting terminals is a very dynamic time. I fully expected that we might have one or two things that we might need to talk about in terminal counting, but it was extremely smooth. There was nothing to talk about.”
This power test is the latest major hurdle between the SLS rocket and a launch attempt later this year. There is still work to be done and the service has to decide if another wet dressing test is needed. But Mike Sarafin, director of the Artemis I mission, said he believed NASA had completed about 90 percent of the test targets to date.
In addition to repairing the leaking hydrogen seal, NASA still needs to roll the rocket back into the Vehicle Assembly Building to install and arm the termination system. This project is likely to rule out a launch attempt before the end of September at the earliest.
