NASA plans to roll the SLS rocket back to the launchpad next Thursday, in preparation for a April 1 launch of the Artemis II flight that will send humans beyond low-Earth orbit for the first time since 1972.
Agency officials today concluded a two-day flight readiness review of the 10-day mission that will send NASA astronauts Reid Wiseman, Victor Glover and Christina Koch and Canadian astronaut Jeremy Hansen around the moon.
“We had extremely thorough discussions, very open, transparent. We talked a lot about our risk posture and how we’re mitigating those risks,” Lori Glaze, NASA’s acting associate administrator for the Exploration Systems Development Mission Directorate, told reporters in a post-review press conference. She noted the Artemis II crew participated in the review, which “really reinforced the importance of having open, honest discussions about our path forward and about the risks that we’re asking them to take.”
Artemis II has launch windows April 1-6, according to the agency’s launch availability calendar.
The agency had hoped to launch as early as Feb. 8, but instead had to spend the month resolving the hydrogen leaks and helium flow issues that emerged during prelaunch rehearsals and testing. Most recently, teams on Feb. 20 detected interruptions in the flow of helium to the engine of the SLS rocket’s upper stage, which required NASA to roll back the rocket to the Vertical Assembly Building at Kennedy Space Center for further evaluations. Helium is used to purge engines before ignition and to pressurize tanks previously filled with liquid oxygen or liquid hydrogen propellant.
Engineers had traced the helium issue to a seal in a quick-disconnect connection between the ground systems and the rocket, NASA deputy associate administrator Casey Swails said in remarks earlier today at the Goddard Space Science Symposium in Washington, D.C. That connection “was removed, it was reassembled, and testing confirmed it’s now operating as expected,” she said.
In the press conference, Glaze expressed confidence in the fixes. “At this point, we’ve demonstrated that the seals that we have are the best seals we’ve ever seen,” she said, adding, “the next time we tank [fill] the vehicle will be when we’re attempting to launch.”
The hydrogen leaks emerged during a Feb. 2 wet dress rehearsal meant to practice fueling and other launch day operations. NASA cut the test short because the leaks — located in two supercooled liquid hydrogen propellant lines in the tail service mast umbilical that runs from the base of the rocket’s mobile launch platform to the main tank in its core stage — surpassed a level that NASA’s previous research and testing concluded would not prompt ignition.
After NASA replaced Teflon seals in the hydrogen fittings and conducted the second wet dress rehearsal in mid-February, there was “really no leakage to speak of,” Charlie Blackwell-Thompson, Artemis launch director, told reporters after that test.
Asked for more detail today about the leaks, John Honeycutt, chair of the Artemis II Mission Management Team, said part of the solution could be to “cherry pick” the seals, or conduct more thorough inspections to ensure they have no flaws. Going forward, NASA may also consider waiting until closer to fueling to install the seals, otherwise SLS “just sits there, assembled like that for quite some time before we roll out” to the launch pad, he added.
NASA has decided to forego a third wet dress rehearsal, because “we’re going to be in a good posture when we roll out this next time” due to the various fixes, Honeycutt said.
The Artemis II astronauts are to loop around the moon in their Orion spacecraft, checking out the handling quality and life support systems in preparation for the Artemis IV lunar landing, targeted for 2028. NASA last month also inserted a new test: a 2027 docking demonstration in low-Earth orbit between Orion and one or both of the commercial lunar landers in development.