On Monday, on its fourth attempt, what NASA completed was essentially a countdown test of the rocket that will carry astronauts to the moon.
But agency technicians said it was too early to tell if the test would be enough to give the go-ahead for the rocket, the Space Launch System, to launch the Orion capsule on a test flight around the moon without astronauts on board.
Even if the countdown rehearsal went perfectly, this mission, Artemis 1, probably won’t take off before the end of August. That flight will be the starting point for the United States to return astronauts to the lunar surface more than half a century after the Apollo 17 mission.
On top of the launch pad at the Kennedy Space Center in Florida, the fuel tanks were filled for the first time with 890,000 liters of liquid oxygen and 2,400,000 liters of liquid hydrogen. Issues during three previous attempts in April were resolved.
“I think it was a very successful day, once again hitting most of the goals,” managing editor Charlie Blackwell-Thompson said during a press conference on Tuesday.
But a new problem arose: hydrogen leakage from the fuel conductor. By heating and cooling the conductor, the engineers expected the seal to move far enough to stop the leak. But it didn’t work.
During the actual launch, this problem was the end of the countdown to the 98-meter rocket.
But Monday’s exercise was what NASA calls a wet test — wet due to the actual flow of fuel into the tanks — designed to solve loopholes and procedures without cranking the burning engines and ascending the rocket into space.
With the countdown paused at T-10 minutes, engineers came up with a plan where the valve would be closed to stop the leak and errors would be suppressed to allow the countdown to proceed with testing of other missile components and launch procedures.
Blackwell-Thompson agreed to the plans and the countdown continued until it was over, as expected, with 29 seconds remaining. Liquid oxygen and liquid hydrogen were then drained from the rocket.
On Tuesday, NASA technicians said they had to analyze the data to see what they still needed to do before they felt ready to launch the rocket. The Space Launch System and Orion, the capsule in which the astronauts will stay, are core components of Artemis, the NASA program that should send astronauts to the Moon.
However, NASA technicians were pleased with the progress.
The filling of the reservoirs and the countdown very close to zero are important milestones, said Thomas Whitmer, associate deputy director of NASA’s Joint Exploration Systems Development.
“We’re looking into the puzzle to see what pieces we still can’t put together,” Whitmer said. “But we put a lot of pieces together and have a pretty good idea of where the puzzle is at this point.”
In April, three attempts at a wet trial ended early due to various problems. The missile was moved to a giant garage called the Vehicle Assembly Building, where technicians could more easily diagnose problems and make repairs. The gap also gave an outside supplier time to upgrade its facilities that supply nitrogen gas — used to purge hazardous gases — at the Kennedy Space Center. During two of the attempts, interruptions in the nitrogen supply delayed the countdown.
NASA may decide to run another wet test, or it may decide that it has enough data and return the rocket to the Vehicle Assembly Building one last time for final launch preparations, which include installing a self-destruct mechanism to destroy the rocket if something goes wrong during flight.
For Artemis 1, the rocket will launch and send the Orion capsule on a long journey around the moon. Then the capsule rotates again to return to the Earth’s atmosphere and plunge into the ocean.
Artemis’ second flight, scheduled for 2024, will have astronauts on a similar flight, without landing on the moon. Artemis 3 will be the first moon landing by astronauts since 1972. NASA has suggested a date of 2025 for such a manned flight, but it may face further delays. / Translation by RENATO PRELORENTZOU
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