The fourth and most recent attempt at a full launch rehearsal of NASA’s Space Launch System went reasonably well, and despite some lingering issues and uncertainties, the agency is sending the rocket back to the hangar for final preparations in advance of its first flight. That inaugural launch will represent Artemis 1, the first mission in NASA’s Artemis lunar program.
In a press release today, NASA — to my surprise — said it is done testing SLS after reviewing data from the recent launch rehearsal. That another full-blown rehearsal would be required seemed likely to me on account of an unresolved hydrogen leak linked to a faulty quick-connect fitting, which subsequently prevented ground teams from practicing the fully scheduled launch countdown on Monday. The goal was to reach T-10 seconds, but the launch controllers decided to quit the rehearsal at T-29 seconds for safety reasons.
“NASA plans to return SLS and Orion to the pad for launch in late August,” says the release. “NASA will set a specific target launch date after replacing hardware associated with the leak.”
Despite the hydrogen leak and the incomplete countdown, Monday’s wet dress did appear to go well. The ground teams finally managed to fully load SLS with propellants. Upwards of 755,000 gallons of cryogenic liquid oxygen and liquid hydrogen were supplied to the rocket’s two stages, which the teams had failed to do during the first three attempts. What’s more, all of the issues experienced during the first three wet dress rehearsals appear to have been resolved. The Orion spacecraft, currently sitting atop the rocket, also performed well during the test.
Said Tom Whitmeyer, NASA’s exploration systems manager, during a media teleconference on Tuesday: “We think we had a really successful rehearsal,” adding that there is “relative risk” is running a fifth wet dress, with the 322-foot-tall (98-meter) rocket standing fully exposed on the launch pad.