NASA says it is ready for a fourth attempt to launch the massive SLS rocket

NASA says it is ready for a fourth attempt to launch the massive SLS rocket

NASA's SLS rocket will be seen at sunrise on June 7, 2022, after its second trip to the launch site.
Enlarge / NASA’s SLS rocket will be seen at sunrise on June 7, 2022, after its second trip to the launch site.

Trevor Mahlmann

NASA has been trying to conduct a critical fuel test of its Space Launch System rocket for almost three months, and now the agency says it is ready to try again.

This will be NASA’s fourth attempt to charge the first and second stages of the SLS rocket with liquid hydrogen and liquid oxygen and to go deep into a launch-down countdown before the test ends at T-10 seconds. The space agency plans to call its team of engineers and technicians to its stations on Saturday night and start refueling on Monday morning, June 20th.

“Our team is ready to go,” said Charlie Blackwell-Thompson, NASA’s launching officer for the Artemis I mission, which represents a test flight for the SLS vehicle and Orion spacecraft. “We are really looking forward to coming back to this test and starting on Saturday night and are really looking forward to the refueling operation.”

After more than a decade of development work – and tens of billions of dollars in costs – NASA and a fleet of contractors rolled out a pre-assembled SLS rocket to the launch pad for the first time on March 17, 2022. In April, on three separate occasions, the space agency tried to complete refueling tested. On April 16, after a third failed attempt, NASA said it would need to roll back the rocket from the launch pad at the Kennedy Space Center in Florida to the vehicle assembly building for repairs.

The most significant problem was a leak of liquid hydrogen at the tail service mast umbilical, which is one of the structures on the large mobile launch tower that provides power and fuel to the rocket during refueling and countdown. During a conversation with reporters on Wednesday, Blackwell-Thompson said that this and other work had been completed. “The team has really done a fantastic job of addressing the issues we saw in wet dress three,” she said.

Earlier this month, NASA rolled the rocket back to launch pad, 39B, before the second test. Since then, NASA and its contractors have been working to prepare the vehicle for the refueling test.

Although NASA has completed many of its test targets during the three previous trials, the most dynamic parts of the wet dress repeat test will come in the final hours with a fully fuel-powered vehicle. NASA is not there yet – during the most advanced fuel test in April, NASA managed to charge 49 percent of the fuel tank for liquid oxygen in the nuclear phase and 5 percent of the tank with liquid hydrogen.

A completed test will require that the fuel is fully charged at both the core stage and the upper stage and then goes into an hour-long countdown. On Monday, NASA intends to start charging fuel at 07.00 ET (1100 UTC) and continue with terminal countdown. At T-33 seconds, the plan is to recover and go into a second countdown, this time taking the vehicle all the way down to T-10 seconds. This should happen sometime on Monday afternoon.

NASA officials have said they will not set a launch date for the Artemis I mission until the wet dress test is complete and there is at least a preliminary review of the data. During Wednesday’s talk, NASA’s Chief Development Officer Jim Free said August 23 to September 6 is the earliest window under which the Artemis I mission could start.

Such a launch date, however, presupposes that the test for wet dresses is completed on time and that few (if any) problems are found that require follow-up work. Although this is possible, it seems unlikely given that more problems are likely to arise during fuel charging and countdown operations.

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