NASA on track for SLS launch between August 23 and September 6 for Artemis I lunar mission [U]

Update: As of July 20, NASA says it is holding three placeholder dates for possible launch targets: August 29 between 8:33 a.m. and 10:33 a.m. ET, September 2 between 12:48 p.m. and 2:48 p.m. ET, and September 5 between 5:12 p.m. and 6:42 p.m. ET. Mission duration would be 42 days, 39 days, and 42 days, respectively.

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NASA conducted its fourth wet dress rehearsal attempt for its Space Launch System rocket this week, completing a critical trial run at fueling the rocket mostly without issue. Officials were uncertain one day after the test if the Moon rocket would require another round of fueling. The agency has since communicated that it intends to launch SLS as early as last August without a fifth go at working out the kinks during fueling.

Return to the Moon

Artemis I is the first mission of NASA’s modern Moon program as well as the first launch of the Space Launch System rocket. The uncrewed mission will send NASA’s Orion spacecraft to lunar orbit before returning back to Earth.

Pending a successful mission, NASA will proceed with Artemis II in 2024 that will be the first lunar orbit mission to include astronauts since the Apollo program of the 60s and 70s. A third mission called Artemis III involves boots on the Moon and will be the first mission to send a woman and person of color to the lunar surface.

Next steps

But first, NASA needs to validate SLS and Orion on an uncrewed mission. NASA has scheduled an Artemis mission briefing for Friday, June 24, where it is expected to publicly announce next steps for SLS.

Ahead of the briefing, Stephen Clark at Spaceflight Now has reported that NASA intends to move forward without another wet dress rehearsal attempt:

With the countdown dress rehearsals complete, ground crews at Kennedy are preparing to roll the 322-foot-tall (98-meter) Space Launch System moon rocket to the Vehicle Assembly Building. The return to the VAB will end the Wet Dress Rehearsal, or WDR, campaign was NASA moves closer to launch of the long-delayed Artemis 1 test flight around the moon, sources said late Wednesday.

The report has since been updated with confirmation from a NASA spokesperson.

Launch window

When should we expect the first Space Launch System rocket launch to occur? NASA says it could be ready to go as early as late August. Pushing Orion into lunar orbit requires certain conditions to be met, however, so NASA says the launch window opens and closes periodically:

To determine potential launch dates, engineers identified key constraints required to accomplish the mission and keep the spacecraft safe. The resulting launch periods are the days or weeks where the spacecraft and rocket can meet mission objectives. These launch periods account for the complex orbital mechanics involved in launching on a precise trajectory toward the Moon while the Earth is rotating on its axis and the Moon is orbiting Earth each month in its lunar cycle. This results in a pattern of approximately two weeks of launch opportunities, followed by two weeks without launch opportunities.

According to NASA, these are the available launch dates for SLS through the end of this year:

August 23 – September 6 

• 12 launch opportunities 
• No launch availability on August 30, 31, and Sept. 1 

September 19 – October 4 (preliminary) 

• 15 launch opportunities 
• No launch availability on Sept. 29 

October 17 – October 31 (preliminary) 

• 11 launch opportunities 

• No launch availability on October 24, 25, 26, and 28 

November 12 – November 27 (preliminary) 

• 12 launch opportunities 
• No launch availability on November 20, 21, and 26 

December 9 – December 23 (preliminary) 

• 11 launch opportunities 
• No launch availability on December 10, 14, 18, and 23

Update 6/24: NASA plans to return Space Launch System to the Vehicle Assembly Building as soon as July 1. Six to eight weeks of work will follow, which doesn’t rule out a late August or early September launch if everything goes as planned. As mentioned above, the next launch window opens September 19 through October 4. The agency says the late August launch window is still on the table for now.