NASA's Artemis 1 moon mission will lift off one month from today (July 29), if all goes according to plan.
That target date is not set in stone, however; the Artemis 1 team must meet a variety of checkouts and other milestones to make it happen. Indeed, Aug. 29 is just one of three "placeholder" dates in an upcoming Artemis 1 launch window, along with Sept. 2 and Sept. 5, NASA officials have said. (A formal target will likely be nailed down a week or two before that window opens.)
As its name suggests, Artemis 1 will be the first mission in NASA's Artemis program of lunar exploration, which aims to establish a permanent human presence on and around the moon by the late 2020s. It will be the first flight for the powerful but long-delayed SLS and the second for Orion, which aced a quick test flight to Earth orbit back in 2014.
NASA has been gearing up for Artemis 1 for months now. For example, the agency rolled the SLS-Orion stack out to Launch Complex 39B at Kennedy Space Center (KSC) in Florida in mid-March, two weeks ahead of a "wet dress rehearsal," a crucial series of tests that included a simulated launch countdown and fueling of the SLS.
Technical issues scuttled that attempt, however, and the Artemis 1 stack was rolled off the pad and back to KSC's Vehicle Assembly Building (VAB) in late April to make some repairs.
Those fixes took about a month. The SLS and Orion were rolled back out to the pad in early June for another crack at the wet dress, which began on June 18. Technicians noticed a hydrogen leak during fueling operations on June 20 but were able to work past it, and mission team members ultimately declared the rehearsal a success.
The Artemis 1 stack rolled back to the VAB for further inspection and maintenance on July 2 and remains there still, being prepped for its impending liftoff.
Artemis 1 is a shakeout cruise designed primarily to show that SLS and Orion are ready to carry astronauts, but the mission has secondary goals as well. For example, 10 cubesats will hitch a ride on the huge moon rocket. These tiny spacecraft will perform a variety of off-Earth work, from hunting for water on the moon to solar sailing to an asteroid to testing how deep-space radiation affects yeast cells.
Artemis 1 will be a long mission, but the exact duration depends on the liftoff date, thanks to orbital dynamics. For instance, launches on Aug. 29 or Sept. 5 would result in a 42-day mission, but a Sept. 2 liftoff would kick off a 39-day flight. In every case, Orion will come back to Earth for a parachute-aided ocean splashdown.
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or on Facebook.
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Michael Wall is a Senior Space Writer with Space.com and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.