UPDATE for 9 p.m. ET: NASA's Orion spacecraft has successfully returned to Earth to return its Artemis 2 astronauts to Earth. See video and photos of the Artemis 2 splashdown in our wrap story. See our LIVE Artemis 2 splashdown updates for more.
The Artemis 2 astronauts are almost home.
The quartet's Orion capsule will return to Earth tonight (April 10), bringing an end to the first crewed moon mission since Apollo 17 back in 1972. You can watch the splashdown live here on Space.com and follow all the action with our Artemis 2 live blog.
If all goes according to plan, the spacecraft will splash down at 8:07 p.m. EDT (0007 GMT on April 11) in the Pacific Ocean, not far off the coast of San Diego — the same general area where the uncrewed Artemis 1 moon mission came down in December 2022. And there are very good reasons why NASA keeps returning to this spot.
For starters, it's wet. And that's important, because Orion — like the Apollo capsules before it — is designed to splash down in the ocean, not land on terra firma.
And the waters off San Diego — as opposed to Los Angeles, say, or San Francisco — make a lot of sense, because the city hosts a pretty important naval installation.
"Naval Base San Diego is homeport to the Pacific Fleet Surface Navy, with 60 U.S. Navy ships and two auxiliary vessels," the base's official website states. "Naval Base San Diego is also home to more than 200 tenant commands, each having specific and specialized fleet support purposes."
That support is crucial to NASA, which coordinates its crew-recovery operations with the Navy. Indeed, the vessel that will pick up the four Artemis 2 astronauts (NASA's Reid Wiseman, Victor Glover and Christina Koch, and the Canadian Space Agency's Jeremy Hansen) is the USS John Murtha, an amphibious transport dock ship that's homeported at Naval Base San Diego.
The seas off San Diego are also generally benign and well-understood, another important factor for a crewed mission's splashdown zone.
So, the area "is a practical choice: predictable Pacific recovery conditions, nearby naval support and a well-practiced handoff from capsule to ship," Aaron Rosengren, an expert in orbital mechanics at the University of California San Diego, told UC San Diego Today on Wednesday (April 8).
Artemis 2's "free-return trajectory," which sent it on a single, dramatic loop around the moon, "set the broad fact that Orion would come back to Earth in the Pacific," Rosengren said. The Artemis 2 team homed in on the San Diego area by making a few additional, precise engine burns, he added.
The last of those burns will occur today at 2:53 p.m. EDT (1853 GMT), if all goes according to plan. At 7:33 p.m. EDT (2333 GMT), Orion's crew module will separate from its service module, which has been providing power and propulsion throughout the 10-day mission.
Twenty minutes later, the crew module will hit Earth's atmosphere over the Pacific, about 2,000 miles (3,200 kilometers) southwest of San Diego. Orion will be traveling nearly 24,000 mph (38,620 kph) at that point, so it'll cover that ground pretty quickly; splashdown is expected at 8:07 p.m. EDT (0007 GMT).
The USS John Murtha will be in the area, waiting to welcome the four astronauts back to Earth — and to help them get to dry land safe and sound.
