The first launch attempt for NASA’s Artemis 1 mission on Monday, Aug. 29, ended in a scrub. That day, NASA managers briefed the press, citing several glitches, including a tetchy hydrogen leak, a lightning strike that delayed fuel loading, and a valve problem. The main showstopper, however, was one of the rocket’s four core-stage engines apparently not cooling to the temperature required for blast off.
Although that temperature reading might have been due to a sensor error, even if all the other issues had been resolved last week, there were still weather complications that would have likely stalled any attempt to take flight. Artemis 1’s planned launch was delayed until the weekend — but things didn’t improve.
While loading the rocket’s supercooled liquid hydrogen fuel on Saturday, Sept. 3, NASA’s next-gen Space Launch System (SLS) encountered a new and “large” leak that presented a fire hazard, agency officials said in a press conference. Engineers were forced to modify their procedures to try to get the leak to self-seal. (Hydrogen is the smallest atom, so it wants to escape closed systems with alacrity, especially in liquid form.) Ultimately, when the leak persisted, the launch control team scrubbed their second attempt to shoot for the Moon.
The exact cause of the leak is unclear, but it has been traced back to the “quick disconnect” interface that connects the SLS core stage to the propellant line of the rocket’s mobile launch tower. The Artemis 1 launch team recently decided to replace the seal on the misbehaving interface, according to a NASA update on Tuesday, Sept. 6. But whether or not the rocket will ultimately have to go back to the garage remains uncertain.
“Performing the work at the pad requires technicians to set up an enclosure around the work area to protect the hardware from the weather and other environmental conditions, but enables engineers to test the repair under cryogenic, or supercold, conditions,” officials wrote in Tuesday’s update.
“Performing the work at the pad also allows teams to gather as much data as possible to understand the cause of the issue,” they added. “Teams may return the rocket to the Vehicle Assembly Building (VAB) to perform additional work that does not require use of the cryogenic facilities available only at the pad.”
Whether Artemis 1 remains on the launch pad or must be returned to the VAB, NASA Administrator Bill Nelson reminded the world last week that “the cost of scrubs is a lot less than failure.” And that claim is certainly beyond dispute.
The current projected launch date for Artemis is now Sept. 27, with Oct. 2 as a potential backup. Assuming SLS does have to be sent back to the shop, the next likely launch window for Artemis 1 will run from Oct. 17 to Oct. 31.
Editor’s note: This story has been updated to reflect NASA’s new intended launch date for SLS.