The first mission of NASA's Artemis moon program is in the books.
An uncrewed Orion capsule splashed down in the Pacific Ocean off the coast of Baja California this afternoon (Dec. 11), bringing a successful end to NASA's historic Artemis 1 moon mission after a 1.4 million-mile (2.3 million kilometers) flight. The splashdown occurred 50 years to the day of NASA's Apollo 17 moon landing, the last astronaut mission to touch down on the lunar surface.
"Splashdown! From Tranquility Base to Taurus-Littrow to the tranquil waters of the Pacific, the latest chapter of NASA's journey to the moon comes to a close: Orion back on Earth," NASA spokesperson Rob Navias said during the agency's livestream of the event on Sunday. (Tranquility Base and Taurus-Littrow were the landing sites of Apollo 11 and Apollo 17, the first and final Apollo moon landing missions, respectively.)
Artemis 1 was a shakeout cruise for Orion, NASA's Space Launch System (SLS) megarocket and their associated ground systems. Further analyses await, but early indications are that all of this gear passed the test with flying colors — meaning NASA can likely start gearing up for the first crewed Artemis flight, a round-the-moon effort in 2024.
A delayed but picture-perfect launch
NASA originally tried to launch Artemis 1 in late August, but several technical glitches, including a leak of liquid hydrogen propellant, pushed things back a month.
And then Mother Nature intervened. In late September, the Artemis 1 team rolled the SLS and Orion off Pad 39B at NASA's Kennedy Space Center (KSC) in Florida to shelter from Hurricane Ian. The Artemis 1 stack stayed inside KSC's huge Vehicle Assembly Building for more than a month, getting some upgrade and repair work done during that stretch.
Team members rolled the rocket and capsule back out to the pad on Nov. 4, seemingly after the end of hurricane season. However, another big storm slammed into the Space Coast on Nov. 10 — Nicole, which hit Florida as a Category 1 hurricane but quickly weakened to a tropical storm.
SLS and Orion weathered Nicole on the launch pad, and did so in good shape; inspections soon revealed that both vehicles were ready for liftoff. That launch — the first ever for the SLS and the second for Orion, which flew to Earth orbit briefly in December 2014 — occurred on Nov. 16, and it was a sight to behold.
The SLS sent Orion aloft exactly as planned. The huge rocket generated 8.8 million pounds of thrust at liftoff, making it the most powerful launcher ever to fly successfully.
"The first launch of the Space Launch System rocket was simply eye-watering," Artemis 1 mission manager Mike Sarafin said in a statement on Nov. 30.
In photos: Artemis 1 launch: Amazing views of NASA's moon rocket debut
Orion hits its marks
Orion experienced a few hiccups during flight. Shortly after liftoff, for example, the capsule's navigating star trackers returned anomalous readings, a problem that the team soon traced to "dazzling" by Orion's thrusters. Overall, however, the capsule performed well during its debut journey beyond Earth orbit, checking off milestone after milestone as planned.
On Nov. 25, the capsule arrived in distant retrograde orbit (DRO) around the moon, a highly elliptical path that took Orion 40,000 miles (64,000 km) from the lunar surface at its most distant point.
On Nov. 26, the spacecraft got farther from Earth than any other spacecraft designed to carry humans, breaking the old record of 248,655 miles (400,171 km) set in 1970 by the Apollo 13 command module. Two days later, Orion reached its maximum distance from its home planet, extending the record to 268,563 miles (432,210 km).
Orion left the lunar DRO on Dec. 1, then headed for home with a 3.5-minute-long engine burn during a close flyby of the moon on Dec. 5. That long journey, and the 25.5-day-long Artemis 1 mission, finally came to an end on Sunday.
The timing was appropriate, coming 50 years to the day after Apollo 17 astronauts Gene Cernan and Harrison Schmitt touched down on the moon. Cernan and Schmitt left the lunar surface on Dec. 14, 1972, and no humans have been back since.
Orion barreled into Earth's atmosphere over the Pacific Ocean, far off the western coast of South America, at 12:20 p.m. EST (1720 GMT) on Sunday. When that happened, the spacecraft was going about 25,000 mph (40,000 kph), or 32 times the speed of sound.
This tremendous speed generated huge amounts of friction, putting Orion's 16.5-foot-wide (5 meters) heat shield to the test. The heat shield, the biggest of its kind ever flown, endured temperatures around 5,000 degrees Fahrenheit (2,800 degrees Celsius), or roughly half as hot as the surface of the sun.
Shortly after entering Earth's atmosphere, Orion left again, bouncing off the upper layers of air like a rock skipping off the surface of a pond. This "skip maneuver," which no human-rated spacecraft had ever performed before, allows the capsule to cover greater distances and land more precisely during reentry, NASA officials have said.
Orion's three main parachutes deployed at at 12:37 p.m. EST (1737 GMT), slowing the capsule's descent. The spacecraft splashed down right on schedule at 12:40 p.m. EST (1740 GMT), about 100 miles (160 km) off the west coast of the Baja Peninsula.
A U.S. Navy ship, the USS Portland, was waiting in the area. The Portland will haul Orion aboard and ferry it to port in San Diego, a journey that will take about a day, NASA officials have said. From there, Orion will travel to KSC for in-depth inspections and analysis.
"This is an extraordinary day," NASA Administrator Bill Nelson told Navias shortly after splashdown. "It’s historic, because we are now going back into space — into deep space — with a new generation."
Preparing for crewed flight
Provided none of the postflight analyses reveal any serious issues, NASA will be free to begin gearing up for the Artemis program's first-ever crewed flight — Artemis 2, which is scheduled to launch astronauts around the moon in 2024.
It only gets more ambitious from there. The agency plans to land astronauts near the moon's south pole on Artemis 3 in 2025 or 2026, a mission that will employ SpaceX's huge new Starship vehicle as a lunar lander. Future Artemis missions will work to set up a research outpost in the south polar region, which is thought to be rich in water ice.
NASA also plans to build a small moon-orbiting space station called Gateway to support Artemis activities. The first elements of Gateway are expected to lift off atop a SpaceX Falcon Heavy rocket in late 2024.
Artemis is a big project — an effort to establish a long-term sustainable human presence on and around the moon, as opposed to the "flags and footprints" approach of Apollo. The successful completion of Artemis 1 allows NASA to start focusing on those bold next steps.
Editor's note: This story was updated at 1:05 p.m. EST to correctly attribute the splashdown quote to NASA spokesperson Rob Navias (rather than Derrol Nail) and to add a quote from agency chief Bill Nelson.
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 Facebook.