NASA delays rollout of Artemis 1 moon mission's SLS megarocket until March. Hear why today.

NASA won't roll its first moon-bound megarocket out to the launch pad any earlier than March, again delaying the launch of its Artemis 1 mission.

Agency officials will discuss the decision during a news conference Wednesday (Feb. 2) at 12 p.m. EST (1700 GMT); NASA will broadcast audio of the event on NASA TV and you can also listen live here at Space.com courtesy of the agency. However, the agency did provide an initial explanation for the delay for the mission to the moon.

"While the teams are not working any major issues, NASA has added additional time to complete closeout activities inside the VAB [Vehicle Assembly Building] prior to rolling the rocket out for the first time," agency officials wrote in a statement.

Related: NASA's Artemis 1 moon mission explained in photos

NASA had previously been planning to launch the flight sometime in March after a key testing procedure in late February. The agency has not provided a new estimate for when Artemis 1 might blast off from its Pad 39B at the Kennedy Space Center (KSC) in Florida but said in a statement that it is looking at dates in April and May.

Artemis 1 will be an uncrewed mission of NASA's new Orion spacecraft around the moon during a weekslong flight to test NASA's preparedness to return astronauts to the moon for the first time since 1972. The Orion capsule will be launched by the first Space Launch System (SLS) megarocket to blast off in a much-awaited milestone for the agency.

Assuming all goes well with Artemis 1 this year, a second mission would send four astronauts around the moon, with the third mission in the series landing a crew at the lunar south pole. Those flights are currently expected to occur in 2024 and 2025.

However, there's a long way to go before NASA can launch those flights. Right now, the agency said, the focus is on final integrated tests on the SLS-Orion duo.

NASA officials will discuss that process during today's news conference, which according to the statement will include Tom Whitmeyer, the deputy associate administrator for exploration systems development; Mike Bolger, Exploration Ground Systems program manager at KSC in Florida; and Mike Sarafin, the mission manager for Artemis 1.

When the Artemis 1 megarocket does finally roll out to Launch Pad 39B at KSC , the next step will be a wet dress rehearsal that simulates every step of launch, including fueling up the rocket.

NASA will only announce a target launch date after that procedure is complete; the rocket must also roll back inside the Vehicle Assembly Building for final checks before blasting off.

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Meghan Bartels
Senior Writer

Meghan is a senior writer at Space.com and has more than five years' experience as a science journalist based in New York City. She joined Space.com in July 2018, with previous writing published in outlets including Newsweek and Audubon. Meghan earned an MA in science journalism from New York University and a BA in classics from Georgetown University, and in her free time she enjoys reading and visiting museums. Follow her on Twitter at @meghanbartels.