If successful, Artemis I will be followed by a crewed mission, with no landing on the Moon. It will be Artemis III that will get the honor of placing American boots on Earth's satellite once more.
To follow our live text coverage of the launch, keep this page open. For the visual experience, NASA's live broadcast, check the video below.
12:44 UTC Rocket is in stable configuration, mostly tanked.
12:43 UTC Artemis I launch scrubbed for today, next opportunity on September 2, 12.48 pm ET, but pending test results on engine no. 3.
12:32 UTC Artemis I launch window now officially open. If they don't leave the pad in the next two hours, the SLS rocket and the Orion spaceship are not going anywhere today. (photo: NASA)
12:25 UTC Moon rocket launch countdown has been on hold for about an hour.
12:20 UTC Artemis I SLS launch now seriously behind schedule.
11:36 UTC Engineers say the potential crack spotted earlier is nothing structural, core stage seems to be solid.
11:22 UTC NASA stops countdown at T-minus 40 minutes, timer on hold.
11:06 UTC Teams working on next steps to solve engine issue.
10:57 UTC Engine no. 3 still not bleeding properly after troubleshooting.
10:42 UTC Sun is rising over the SLS on launch pad 39B. (photo: NASA)
10:34 UTC NASA begins live streaming the Artemis I SLS launch process. Watch everything live in the video above.
10:33 UTC A crack seems to have appeared in one of the flanges (connection joints that are attached to the two tanks) on the core stage of the SLS. Teams are investigating.
10:31 UTC One of SLS' RS-25 engines (engine no. 3) is experiencing an issue, not being properly "conditioned through the bleed process." Teams are working on the problem now.
10:09 UTC Planned liquid hydrogen engine bleed test begins.
10:07 UTC The Infinity Science Center in Pearlington, Mississippi, host to NASA's Stennis Visitor Center, is throwing a free Artemis I watch party starting 7.00 am local time.
09:43 UTC SLS core stage in detail. (photo: NASA)
09:33 UTC Artemis I launch countdown now reads under four hours.
09:30 UTC Core stage liquid oxygen and liquid hydrogen tanks fully loaded, replenish starts. This will ensure tanks are at full capacity. Fueling of the ICPS continues.
09:26 UTC Live broadcast of the Artemis I SLS launch starts at 6:30 am EDT.
09:24 UTC Artemis I mission overview.
09:07 UTC Core stage tanks filled at 92% liquid oxygen, 94% liquid hydrogen.
08:55 UTC NASA moves to fueling the SLS interim cryogenic propulsion stage (ICPS), the upper stage of the rocket. Core stage oxygen tank is at 80%, hydrogen at 61%. Launch in announced window still on track.
08:44 UTC Liquid oxygen tank is at 75%, hydrogen at 48%, both in fast fill mode.
08:29 UTC Artemis I SLS, Orion on the pad, August 29, 2022.
08:25 UTC NASA declares hydrogen leak acceptable.
08:18 UTC Hydrogen fast fill resumes after manual chill down, troubleshooting and monitoring of the leak continues.
07:50 UTC Hydrogen leak comes back to haunt NASA: spike in the amount of hydrogen that is allowed to leak into the purge can recorded, reverse flow started. Problem is being "troubleshot," cause may not be the same as the one seen during the wet dress rehearsal test.
07:38 UTC "Teams are assessing LH2 propellant loading on the NASA SLS rocket for the Artemis I mission," NASA says. Half an hour ago, the core stage was 24% filled with liquid oxygen, liquid hydrogen at 4 percent.
07:29 UTC Artemis I on the launch pad as seen from a distance, August 28, 2022.
07:16 UTC Artemis I tanking operations are underway.