The third try was not the charm for NASA's Artemis 1 moon mission.
Today (April 14), the space agency called off the latest attempt to fuel up Artemis 1's huge Space Launch System (SLS) rocket, a crucial part of the mission's "wet dress rehearsal" at Kennedy Space Center in Florida (KSC). Artemis 1 team members detected a leak of liquid hydrogen (LH2) — one of SLS' two propellants, along with liquid oxygen (LOX) — during tanking operations. That brought a halt to today's fueling activity, as well as other key wet dress procedures.
"The team will keep the [SLS] core stage LH2 tank at about 5% and the core stage LOX loading will remain stopped. The team will not conduct the terminal countdown activities today as planned and will assess next steps after today's operations," Jeremy Parsons, deputy manager of NASA's Exploration Ground Systems team at KSC, said via Twitter this afternoon.
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As its name suggests, Artemis 1 will be the first mission of NASA's Artemis program of lunar exploration. Artemis 1 will send an uncrewed Orion capsule on a roughly month-long journey around the moon, with the aim of showing that SLS and Orion are ready for crewed missions.
The wet dress rehearsal is one of the most important pre-launch steps for Artemis 1. The multi-day test allows mission team members to practice many of the key procedures leading up to liftoff, including — as noted above — SLS fueling and the launch countdown.
NASA began the Artemis 1 wet dress on April 1 and intended to wrap it up on April 3. But several technical issues cropped up, twice foiling efforts to load propellant into the SLS' tanks. The mission team initially delayed and ultimately aborted the test, to accommodate the launch of the private Ax-1 astronaut mission, which lifted off from a neighboring pad at KSC on April 8.
The plan was to resume the wet dress on April 11. But team members soon discovered a faulty valve in the Artemis 1 stack's mobile launch tower, a problem that pushed the beginning of the procedure back to April 12 and caused a modification to the test design: The team decided to fuel up only the SLS core stage, not its upper stage as well.
The wet dress was supposed to conclude today (April 14), but that's not happening, given that the mission team won't perform the scheduled simulated countdowns. We'll have to stay tuned to learn about the agency's next steps.
Uncertainty also surrounds the Artemis 1 launch date; NASA will not set one until the wet dress is done and the resulting data analyzed, agency officials have said.
Artemis 1 is a prelude to Artemis 2, which is expected to launch astronauts around the moon in 2024. Artemis 3 will land astronauts near the lunar south pole in 2025 or 2026, if all goes according to plan.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or on Facebook.