• NASA officials said the next attempt to launch Artemis I will be September 27, at the earliest.
• The second launch attempt for NASA's Space Launch System rocket was delayed due to a liquid hydrogen leak.

NASA is targeting September 27 as the next launch attempt for its Artemis I moon rocket, with October 2 as a potential backup date, NASA said Monday.

That's if engineers are able to fix the hydrogen leak that halted the last launch attempt on September 3, and if the rocket is allowed to stay on the launch pad without another rollback to Kennedy Space Center's Vehicle Assembly Building.

On Friday, the Artemis I team wrapped up hydrogen leak repairs on Launchpad 39-B in Florida's Kennedy Space Center. NASA plans to conduct fueling tests on September 21 to make sure the source of the fuel leak was removed and the crew is prepared for the next launch attempt.

On September 27, a 70-minute launch window is slated to open at 11:37 a.m. ET. The rocket should splash back on Earth on November 5. The October 2 backup launch date, which has a 109-minute launch window starting at 2:52 p.m. ET, is "under review," according to NASA. If the rocket launches on October 2, it should land back on Earth on November 11.

The space agency also reached out to officials from the US Space Force's Eastern Range — who review and approve all missions that lift off from the Cape Canaveral region — to extend a battery retest requirement on the moon rocket's flight termination system.

Hydrogen fuel woes interrupted the second launch attempt

The new launch dates come after the launch of the Space Launch System and its uncrewed Orion capsule was called off for a second time on Saturday, September 3. At 7:15 a.m. ET, a leak occurred as engineers increased the pressure on the flow of liquid hydrogen into the core stage.

"Teams encountered a liquid hydrogen leak while loading the propellant into the core stage of the Space Launch System rocket," NASA said in a blog post. "Multiple troubleshooting efforts to address the area of the leak by reseating a seal in the quick disconnect where liquid hydrogen is fed into the rocket did not fix the issue."

After attempts to troubleshoot were unsuccessful, Artemis' launch director called off the launch.

It was the second scrub — NASA's term for calling off a launch on a specific day — for the mega moon rocket. During NASA's first launch attempt on August 29, sensors suggested one of the rocket's four core stage RS-25 engines wasn't cooling down to a safe temperature in time for launch.

"We don't have the launch that we wanted today. I can tell you these teams know exactly what they're doing and I'm very proud of them," Bill Nelson, NASA administrator, said on September 3. "Just remember we're not going to launch until it's right."

1 in 3 chance of a scrub on any given day

In August, NASA engineers tested the rocket's flight termination system, which began a 20-day timeline for launching. If the launch is delayed beyond those 20 days, engineers will have to roll back the rocket for additional testing, Jeremy Parsons, deputy manager of NASA's Exploration Ground Systems, said at a Friday press briefing.

NASA engineers also contend with weather, a common cause of launch delays. The forecast prior to Saturday's attempt showed 60% favorable weather conditions at the beginning of the launch window. "On any given day, there's about a one in three chance that we will scrub for any reason," Melody Levin, a meteorologist at NASA, said at a briefing on Friday, September 2. "Out of those chances of scrubbing, there's a 50% chance that it's due to weather," Levin said.

Additionally, when scheduling a launch attempt, NASA must ensure the Orion capsule doesn't go into an eclipse, or the shadow of the moon, for too long, because it depends on solar power.

More than 400,000 visitors were expected to gather near NASA's Kennedy Space Center in Cape Canaveral, Florida, on Saturday to view the inaugural launch, according to the Space Coast's tourism office.

NASA has spent 17 years and an estimated $50 billion developing the SLS rocket and its Orion spaceship, according to The Planetary Society.

During the Artemis I mission, NASA aims to fly the Orion crew capsule all the way around the moon — farther than any spacecraft built for humans has ever flown — before heading back for a splashdown in the Pacific Ocean.

There won't be people on board during the Artemis I launch. But if the spaceship successfully completes its mission, NASA plans to put astronauts in the Orion module for another trip around the moon, during the Artemis II mission. It's all in preparation for Artemis III, in which NASA hopes to land the first woman and the first person of color on the lunar surface in 2025.

This story has been updated with new information. It was originally published on September 3, 2022.