Hydrogen is particularly energetic, tiny, and difficult to contain, Nasa officials told a briefing.
Along with leakages teams had to troubleshoot a valve issue related to hatch pressurisation, in addition to dropouts of audio communications, Nasa said.
The latest leaks mirror issues that delayed for months the Artemis 1 launch, which was an uncrewed test mission that ultimately circled the moon in 2022.
John Honeycutt, head of the Artemis 2 mission management team, said scientists had been “aggressive” in their testing to understand the Artemis 1 leaks.
But “on the ground, we’re pretty limited as to how much realism we can put into the test. We try to test like we fly, but this interface is a very complex interface. This one caught us off guard,” he continued.
“To me, the big takeaway was we got a chance for the rocket to talk to us, and it did just that,” Honeycutt said.
Moon rush
Mission managers said they are analysing the data collected and making necessary repairs ahead of plans to run another dress rehearsal.
For now, officials said those fixes can be performed at the Florida launchpad.
The eventual Artemis 2 moonshot will send a team of four astronauts on a flyby of Earth’s satellite.
That approximately 10-day mission will lay the groundwork for Nasa’s next planned Artemis phase, when a crewed mission is intended to actually land on the moon.
US President Donald Trump has made it evident that he wants to send astronauts back to the moon as soon as possible, in order to “assert American leadership in space”.
The Artemis 2 astronauts had been in quarantine in Houston but were released following the delay.
“Immense pride seeing the rocket reach 100% fuel load last night, especially knowing how challenging the scenario was for our launch team doing the dangerous and unforgiving work,” said team commander Reid Wiseman on X.
“The crew just shared a peaceful breakfast with our families and we jump back into training tomorrow to start our preps for a March launch to the Moon.”
SpaceX grounds flights
Nasa also said today that its next crew rotation to the International Space Station could be delayed after SpaceX announced it was grounding flights of its Falcon 9 rocket to investigate an unspecified issue.
SpaceX, the private space company owned by Elon Musk, has paused flights of its Falcon 9 rocket following an issue its second stage experienced during a routine launch yesterday of Starlink satellites into orbit.
The grounding could potentially delay the next Nasa crew rotation to the International Space Station, which is slated for February 11, given that those astronauts are launched with a Falcon 9 rocket.
The rocket’s stage “experienced an off-nominal condition during preparation for the deorbit burn”, SpaceX said in a statement, without providing specifics.
“Teams are reviewing data to determine root cause and corrective actions before returning to flight.”
The satellites were successfully deployed.
The Federal Aviation Administration is also investigating the mishap, Amit Kshatriya, a senior Nasa official, told a media briefing, saying preparation for the Crew-12 mission to ISS was contingent on the outcome.
The ISS mission is to launch from Cape Canaveral.
The crew includes Americans Jessica Meir and Jack Hathaway, French astronaut Sophie Adenot and Andrey Fedyaev of Russia.
-Agence France-Presse