In its fourth attempt Monday, NASA has mostly completed a practice countdown for the rocket that will take astronauts to the moon.
But agency officials said it was too early to tell whether the test would be enough to give the rocket, the Space Launch System, the green light to launch the Orion capsule on a test flight around the moon with no astronauts on board.
Even if the practice countdown had gone perfectly, it’s unlikely that mission, Artemis 1, would get off the ground 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.
Sitting on a launch pad at the Kennedy Space Center in Florida, the rocket’s propellant tanks were completely filled for the first time with 196,000 gallons of liquid oxygen and 537,000 gallons of liquid hydrogen in the rocket’s propellant tanks. Problems that had occurred during three previous attempts in April have been resolved.
“I think it was a very successful day and once again it hit most of the targets,” Charlie Blackwell-Thompson, launch director, said during a Tuesday news conference.
However, a new problem arose: a hydrogen leak at a fuel line connector. By heating and then cooling the connector again, the engineers hoped that the seal would displace enough to stop the leak. This is not functional.
During an actual launch, that problem would have been the end of the countdown for the 322-foot-tall rocket.
But Monday’s exercise was what NASA calls a wet, wet dress rehearsal due to the actual flow of fuel into the propellant tanks, which is designed to work out glitches and procedures without the excitement of the engines firing up and the rocket going down. rises into space.
With the countdown clock paused at T-10 minutes, engineers came up with a plan in which a valve would be closed to stop the leak and errors suppressed to allow the countdown to continue to test other rocket components and maintenance procedures. launch.
Mrs. Blackwell-Thompson approved the plans and the countdown continued until, as expected, the countdown ended with 29 seconds remaining. Liquid oxygen and liquid hydrogen were then drained from the rocket.
On Tuesday, NASA officials said they needed to analyze the data to see what they would still need to do before they felt ready to launch the rocket. The Space Launch System and Orion, the capsule on top where astronauts will sit, are essential components for Artemis, NASA’s program to send astronauts back to the moon.
Still, NASA officials were ecstatic with the progress.
Thomas Whitmeyer, NASA deputy associate administrator for Common Exploration Systems Development, said filling the fuel tanks and counting so close to zero were important milestones.
“We’re looking at the pieces of the puzzle to decide which pieces we didn’t get,” Mr. Whitmeyer said. “But we also put a lot of puzzle pieces together, and we have a pretty good idea of what the puzzle looks like at this point.”
In April, three attempts at a wet dress rehearsal ended early due to a variety of problems.
The rocket was returned to a giant garage called the Vehicle Assembly Building, where technicians could diagnose problems and make repairs more easily. The pause also gave time for an off-site supplier to upgrade its facility that provided nitrogen gas, used to purge dangerous gases, to the Kennedy Space Center. During two of the trial attempts, interruptions in the nitrogen supply delayed the countdown.
NASA might decide to do another wet dress rehearsal, or it might decide it has enough data and roll the rocket back to the Vehicle Assembly Building one last time for final launch preparations, which include installing the self-destruct mechanism to destroy the rocket in case something goes wrong during the flight.
For Artemis 1, the rocket would launch and send the Orion capsule on a long journey around the moon. It would then turn around on its way to re-enter Earth’s atmosphere and land in the ocean.
The second Artemis flight, scheduled for 2024, would have astronauts on board for a similar trip, without landing on the moon. Artemis 3 will be the first landing by astronauts since 1972. NASA has proposed a date of 2025 for that manned trip, but could face further delays.