Artemis I launch scrubbed after engine issue

NASA postponed the launch of Artemis I, the mega rocket that aims to go beyond the moon and return to Earth. It's the first launch in NASA's Artemis program, which hopes to return humans to the moon for the first time since 1972.

Here's everything you need to know about the scrubbed launch.

NASA highlighted these issues that factored in the decision to scrub:

What happens next: The launch team will "reconvene tomorrow" to discuss options, Sarafin told reporters Monday.

The next possible launch window is Friday: NASA had already determined more than one launch date for Artemis I before the launch was postponed Monday. The next availability is this Friday, Sept. 2, which is still "in play," according to Sarafin, but engineers still need to troubleshoot the issue to determine if NASA can use that launch window.

The Sept. 2 launch window will open at 12:48 p.m. ET and last two hours.

Friday is still “in play” for a launch of NASA’s Artemis I after Monday’s scheduled launch was scrubbed, Artemis mission manager Mike Serafin said.

Friday is NASA’s next available window to launch. Serafin wouldn’t speculate on what the chances for launch are on Friday. 

The launch was scrubbed largely due to an issue with one of the rocket’s four engines, though officials indicated they don’t think the issue is with the engine itself but instead the process of feeding the engines with liquid hydrogen, which is used to cool the engine for launch. 

Mission managers will meet Tuesday afternoon to evaluate the next steps and to see if Friday’s attempt is possible. They could also delay for much longer amounts of time, including the three-and-a-half-day process of rolling the rocket back to the vehicle assembly building if a more substantial fix is needed.

Weather conditions also factored into the decision to scrub the Artemis I launch today, Mike Sarafin, the Artemis I mission manager, said. 

More background: CNN reported that weather conditions remained 80% favorable for a launch at the beginning of a window that opened at 8:33 a.m. ET. But several issues cropped up after the rocket began fueling after midnight. Offshore storms with the potential for lightning prevented the team from beginning the fueling process, due to start at midnight, for about an hour.

CNN's Ashley Strickland contributed reporting to this post. 

The launch team had trouble getting one of the four RS-25 engines to the proper temperature for liftoff, which led to NASA postponing the launch of Artemis I, NASA said at the beginning of the press briefing on Monday.

The launch was postponed this morning when the launch team discovered an issue with an engine bleed in engine #3. Before the launch, super cold liquid hydrogen is cycled through the engine to get it ready it for launch. Three of the four engines were performing as expected, but engine #3 experienced an issue.

"We did encounter an issue chilling down engine #3. We need the engine to be at the cryogenically cool temperature such that when it starts, it’s not shocked with all the cold fuel that flows through it. So we needed a little extra time to assess that," Sarafin explained.

"When the team started working through that, they also saw an issue with the vent valve at the inner tank," he added.

"So the combination of not being able to get the engine #3 chill down and then the vent valve issue that they saw at the inner tank really caused us to pause today and we felt like a little more time," he noted.

NASA administrator Bill Nelson stressed that "scrubs are just a part of this program," during a news conference speaking on the postponement of launching the Artemis I rocket.

Discussing a space flight that he participated in decades ago with astronaut Hoot Gibson, Nelson said that there were four scrubs from the launch pad. "Looking back had we, after the fifth try, got off to a perfect mission, it would've not been a good day had we launched on any one of those four scrubs."

Mike Sarafin, the Artemis I mission manager, said they have not set a new date for when the launch will be rescheduled, saying the team will "reconvene tomorrow" to discuss options.

He said the team worked through "a number of issues today" both technical and weather related, adding ultimately they "felt like we needed a little more time."

"We will come back and talk about where we stand tomorrow evening," Sarafin said.

Vice President Kamala Harris reaffirmed the United States' commitment to NASA's Artemis program after the mega rocket's launch was postponed due to an engine issue.

Harris was at the Kennedy Space Center in Florida with second gentleman Doug Emhoff to watch the launch.

NASA administrator Bill Nelson said he briefed her after the launch was postponed.

Talking to reporters, she also expressed optimism, saying that “innovation requires this kind of moment.”

CNN's Allie Malloy contributed reporting to this post.

It's no coincidence that the Artemis program is named for the twin sister of Apollo from Greek mythology. Artemis will pick up where the famed Apollo program left off in 1972 — 50 years ago — by sending crewed missions to the moon, but in a new way.

It will be the farthest that any spacecraft built for humans has flown, according to NASA officials.

The Orion spacecraft has hardware and software that will allow future crews to have complete insight into what's happening with their vehicle when they are thousands of miles from home.

Goals of the Artemis program include landing diverse crews of astronauts on the moon and exploring the shadowy lunar south pole for the first time. The ambitious effort also aims to establish a sustained presence on the moon and create reusable systems that can enable human exploration of Mars and perhaps beyond.

All of the objectives for the inaugural Artemis flight will demonstrate capabilities necessary for when Orion carries humans to deep space. The list includes an overall safe flight, the performance of the Space Launch System rocket, testing the heat shield and retrieving the spacecraft once it splashes down in the Pacific Ocean off the coast of San Diego.

Today's historic launch of Artemis I on its mission to the moon was postponed due to an issue with one of the rocket's four engines.

NASA is expected to provide an update later today, but here's what we know so far:

Watch CNN's Kristin Fisher explain all the issues NASA encountered before launch: