The Artemis II astronauts have a make-or-break moment in the dead of night

NASA's Artemis II astronauts will get a swift reminder on their first flight day that moon missions don't adhere to sleep demands. 

The historic human spaceflight, NASA's first beyond low-Earth orbit in over 50 years, launched from Cape Canaveral, Florida, on Wednesday evening at 6:35 p.m. ET. But even after that bone-rattling liftoff, the crew — Commander Reid Wiseman, pilot Victor Glover, Christina Koch, and Jeremy Hansen — won't have downtime. 

First, the rocket's upper stage places the Orion spacecraft into a high-Earth orbit that takes about 24 hours to complete. As it circles the planet, the crew will test life support, communications, and navigation systems while they're still relatively close to home. 

Then comes an awkwardly timed maneuver: the so-called "perigee raise" burn. Mission managers say this unassuming moment sits in the same high‑risk category as liftoff itself. The problem is when that engine burn must happen — right in the middle of the astronauts' sleep. 

"Unfortunately, physics cannot be defied," said Jeff Radigan, lead flight director for the mission. "We have to put the burns where they're necessary for the trajectory."

For the astronauts, that means a very long first day in orbit that requires burning the midnight liquid hydrogen, so to speak. Their day began at about 11:30 a.m. ET on Wednesday, some seven-or-more hours before the launch. 

Once in space, Wiseman and Glover will perform a demonstration of the spacecraft's manual steering. They'll use Orion's spent upper stage — the Interim Cryogenic Propulsion Stage — for docking practice. Cameras and windows will help the pair see how the ship handles approaching and backing away. 

Chief Training Officer Jacki Mahaffey oversees the Artemis II crew as they train for key maneuvers in an Orion spacecraft mockup in Houston, Texas. Credit: NASA / Mark Sowa

Though manual control isn't necessary for this mission, the test is a crucial demonstration of whether the spacecraft can dock with landers during future moon missions. After about 1.5 hours of this piloting exercise, Orion will perform an engine burn to speed away from the upper stage. The discarded propulsion system will then have a controlled splashdown in the Pacific Ocean. 

About 8.5 hours into the flight, the astronauts will finally be allowed to get some shuteye. But it won't last long: Just four hours later, they'll get a wakeup call from Houston about that critical perigee-raise engine burn. 

The maneuver is one of the mission's make‑or‑break moments. It takes Orion's initial, temporary orbit and reshapes it into a stable path ahead of their moon-bound engine firing scheduled for the next day. 

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NASA had little control over the timing. The laws of orbital motion did. Orion has to fire its engine at specific moments — not whenever it’s convenient — to get where it needs to go.

Rather than "bedtime," Glover calls their interrupted first night what it truly is. 

"We’re going to take a nap," he said. 

When the job is complete, the crew can crawl back into their sleeping bags stuck to the walls — for a luxurious 4.5 hours.