NASA's "mega moon rocket" is back on the launch pad.
The Space Launch System, or SLS, is the space agency's newest and most powerful rocket to date and will return astronauts to the moon at some point in 2024 or 2025 as part of the Artemis program.
The rocket began rolling out of the massive vehicle assembly building at 11:16 p.m. ET Thursday, almost 45 minutes ahead of schedule.
The first launch attempt is planned for Nov. 14, at 12:07 a.m. ET. There are two other launch windows — where the Earth and moon are in the right position for the mission — on Nov. 16 at 1:04 a.m. ET and on Nov. 19 at 1:45 a.m. ET.
The launch was supposed to take place on Aug. 29 but was scrubbed after a few issues that included a hydrogen leak. A second launch attempt occurred on Sept. 3, but once again, a hydrogen leak forced NASA to call it down. Though the space agency was hoping for a third attempt in September, Hurricane Ian forced them to roll the rocket back to the vehicle assembly building.
WATCH | NASA calls off moon rocket launch for a second time
But now NASA officials are confident they are ready to go.
"If we weren't confident, we wouldn't roll out," Jim Free, associate administrator at the space agency's exploration systems development mission directorate, said on a media call on Thursday.
The aim of this mission, Artemis I, is to test the new rocket and test the capabilities of the Orion capsule that sits atop the rocket, which will one day return astronauts to the moon. No one will be on board, other than mannequins placed there to test equipment, including a newly developed vest designed to protect astronauts from space radiation.
Artemis II is scheduled to launch in 2024. That mission will see four astronauts — including a Canadian — orbit the moon and then return to Earth.
"This is a challenging mission. We've seen challenges just getting all our systems to work together and that's why we do a flight test," Free said of the un-crewed Artemis I mission. "It's about going after the things that can't be modelled. And we're learning by taking more risk on this mission before we put crew on there."
NASA had hoped to launch in daylight rather than in the wee hours of the morning in order to better see how the rocket performs, but insisted that it would not ultimately make a difference in the test.
"The visual references obviously are what you lose, in terms of launching at night, but obviously we have [infrared cameras]," said Cliff Lanham, senior vehicle operations manager with NASA's exploration ground systems program. "But we have a great number of cameras that we'll still get shots from."
In the meantime, NASA says it is keeping an eye on a developing storm in the Atlantic Ocean.