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By Tariq Malik published 26 August 22

NASA's Artemis 1 mission will launch on the first Space Launch System rocket and its Orion spacecraft on Monday, Aug. 29.

CAPE CANAVERAL, Fla — NASA's Artemis 1 mission will open a new era of U.S. space exploration when it launches to the moon this month, but exactly when it lifts off depends on several factors. 

Artemis 1, the first uncrewed test flight of NASA's Artemis program to return astronauts to the moon, is currently scheduled to lift off from Pad 39B of the Kennedy Space Center in Cape Canaveral on Monday (Aug. 29). Liftoff is currently scheduled for 8:33 a.m. EDT (1233 GMT), weather permitting. You can watch the launch live online on Monday starting at 6:30 a.m. EDT (1030 GMT), courtesy of NASA TV.

Related: NASA's Artemis 1 moon mission: Live updates

NASA has stressed repeatedly that Artemis 1 is, at its core, a test flight. It is the first-ever flight of the agency's new megarocket, the towering Space Launch System (SLS), as well as the first deep-space flight for the new Orion spacecraft. There may be technical glitches that come up during the launch countdown that warrant a delay. 

"The test fight itself carries inherent risk," Jim Free, NASA associate administrator for exploration systems development, said in an Aug. 22 news conference. "This is the first flight of a new rocket and a new spacecraft."

NASA has a two-hour window in which to launch Artemis 1 on Aug. 29. That means the launch could occur anytime between 8:33 a.m. and 10:33 a.m. EDT (1233-1433 GMT), although NASA is targeting the start of the window.

Weather could also cause a delay. Currently, there is a 70% chance of good weather at launch time, according to an Aug. 25 forecast (opens in new tab) from the Space Launch Delta 45 weather group at Cape Canaveral Space Force Station. The primary concerns are thick clouds, surface electrical fields from lightning and the possibility the SLS may have to fly through rain on its ascent. The weather group will issue daily weather updates through launch. You can find those on the Space Launch Delta 45 website (opens in new tab) .

You can launch a Space Launch System of your own with this Estes NASA SLS model rocket (opens in new tab) for a 1:200 scale version of NASA's moon megarocket. Read more about it.

If technical issues or bad weather delay the Artemis 1 mission, NASA does have some options. 

There are two backup launch days in Artemis 1's current flight window: Friday, Sept. 2 and Monday, Sept. 5. Both dates have their own extended launch windows. 

If NASA is forced to go for the Sept. 2 launch date, the Artemis 1 SLS rocket will launch at 12:48 p.m. EDT (1748 GMT) and would have a two-hour window to get off the ground. NASA would have to accept a shorter mission, 39 days instead of the 42-day flight an Aug. 29 liftoff allows for, if the agency opts for this launch date. It would splash down in the ocean on Oct. 11 instead of the original Oct. 10.

The Sept. 5 launch date calls for a liftoff at 5:12 p.m. EDT (2212 GMT). The launch window for this date is a bit shorter, 90 minutes as opposed to two hours, but does allow NASA to pursue a longer 42-day flight. Landing would occur on Oct. 17.

If NASA is unable to launch the Artemis 1 mission during the Aug. 29 to Sept. 5 period, the agency would have to fall back on a series of additional launch windows that run throughout the rest of the year and early 2023. 

In May, the space agency unveiled a calendar of launch opportunities through mid-2023 that met a series of criteria needed for the Artemis 1 mission. That list was updated earlier this month as NASA weighed possible launch options. 

Here's a look at when those additional launch opportunities could occur.

You can download NASA's full Artemis 1 launch availability calendar (opens in new tab) (PDF) to see how the dates stack up.

NASA has four primary requirements that drive how it selects launch dates for Artemis 1. Here's what they are, according to a NASA data sheet (opens in new tab) .

— Artemis 1 moon mission: Live updates

— Webcast: Watch the Artemis 1 moon mission launch

— NASA's Orion spacecraft faces huge test for moon flights

All of those requirements make for a complicated calculus when it comes to determining a launch date for Artemis 1. 

If you're planning to watch NASA's Artemis 1 launch online, Space.com will carry the agency's webcast live on Monday (Aug. 29). A fueling webcast will begin at 12 a.m. EDT (0400 GMT), with the launch webcast beginning in earnest at 6:30 a.m. EDT (1030 GMT). 

NASA is also expected to livestream several post-launch events, including a press conference, confirmation of the trans-lunar injection maneuver and the first views of Earth from the Orion spacecraft. You can see a full schedule in our Artemis 1 webcast guide.

Email Tariq Malik at tmalik@space.com or follow him @tariqjmalik. Follow us @Spacedotcom, Facebook and Instagram.

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Tariq is the Editor-in-Chief of Space.com and joined the team in 2001, first as an intern and staff writer, and later as an editor. He covers human spaceflight, exploration and space science, as well as skywatching and entertainment. He became Space.com's Managing Editor in 2009 and Editor-in-Chief in 2019. Before joining Space.com, Tariq was a staff reporter for The Los Angeles Times covering education and city beats in La Habra, Fullerton and Huntington Beach. He is also an Eagle Scout (yes, he has the Space Exploration merit badge) and went to Space Camp four times as a kid and a fifth time as an adult. He has journalism degrees from the University of Southern California and New York University. To see his latest project, you can follow Tariq on Twitter.

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