The Artemis 1 spacecraft heads into the fall on Sunday to wrap up the historic mission

Wrapping up a 25-day trip around the moon, NASA’s Artemis 1 spacecraft docked on Earth on Saturday, en route to a 25,000-mph re-entry on Sunday that will subject the unmanned capsule to a hellish 5,000 degrees before the Baja California splash. .

In an unexpected but richly symbolic coincidence, the end of the Artemis 1 mission, scheduled for 12:39 p.m., will come 50 years after Apollo’s final moon landing in 1972.

Testing the Orion capsule’s 16.5-foot-wide Apollo-derived Avcoat heat shield is the top priority of the Artemis 1 mission, “and it’s our top priority for a reason,” said the manager of the mission Mike Sarafin.

“There is no arc jet or aerothermal facility here on Earth capable of replicating hypersonic reentry with a heat shield of this size,” he said. “And it’s a completely new heat shield design, and it’s safety-critical equipment. It’s designed to protect the spacecraft and (future astronauts) … so the heat shield has to work.”

launched November 16 on the maiden flight of NASA’s new Space Launch System rocket, the unmanned Orion capsule was propelled out of Earth orbit and toward the Moon for an exhaustive series of tests, testing its propulsion systems , navigation, power and computing in the deep space environment.

While flight controllers encountered still-unexplained failures with its power system, initial “fun” with its star trackers, and degraded performance of a phased-array antenna, the Orion spacecraft and its service module built by the European Space Agency. it worked well overallachieving pretty much all of its main goals up to this point.

“We have collected an immense amount of data characterizing the system performance of the power system, propulsion, CNG (guidance, navigation and control) and to date, the flight control equipment has connected to more than 140 gigabytes of engineering data and images.” said Jim Geffre, Orion’s vehicle integration manager.

The team is already analyzing this data “to help not only understand the performance of Artemis 1, but also play forward for all subsequent missions,” he said.

If all goes well, NASA plans to follow up the Artemis 1 mission by sending four astronauts around the Moon on the program’s second flight, Artemis 2, in 2024. The first Moon landing would occur in 2025-26 when the NASA says that the first woman and the next man will set foot on the lunar surface.

The unmanned Artemis 1 capsule flew half an orbit around the Moon that took it farther from Earth (268,563 miles) than any previous human-classified spacecraft. Two critical firings of its main engine set up a low-altitude lunar flyby last Monday, which in turn put the craft on course for splashdown on Sunday.

NASA originally planned to land the craft west of San Diego, but a predicted cold front bringing stronger winds and rougher seas prompted mission managers to move the landing site about 350 miles south . A splash is now expected south of Guadalupe Island about 200 miles west of Baja California.

Approaching from nearly due south, the Orion spacecraft, traveling at 32 times the speed of sound, is expected to re-enter the perceptible atmosphere at an altitude of 400,000 feet, or about 76 miles, at 12:00 p.m. 8 p.m.

NASA planners devised a unique “jump entry” profile that will cause Orion to skip through the upper atmosphere like a flat stone skipping through still water. Orion will drop from 400,000 feet to about 200,000 feet in just two minutes, then climb back up to about 295,000 feet before resuming its computer-guided fall back to Earth.

Within a minute and a half of entry, atmospheric friction will generate temperatures through the heat shield that will reach nearly 5,000 degrees Fahrenheit, enveloping the spacecraft in an electrically charged plasma that will block communications with the controllers of flight for about five minutes.

After another two-and-a-half minute communications blackout during its second descent into the lower atmosphere, the spacecraft will continue to decelerate as it approaches the target landing site, slowing to about 650 mph, about the speed of sound, about 15. minutes after the entry began.

Finally, at an altitude of about 22,000 feet and a speed of about 280 mph, small parachute pods will deploy to stabilize the spacecraft. The spacecraft’s main parachutes will deploy at an altitude of about 5,000 feet, slowing Orion to a calm of about 18 mph for the splashdown.

Estimated mission duration: 25 days 10 hours 52 minutes, covering 1.4 million miles since the Nov. 16 blastoff.

NASA and Navy recovery teams aboard the USS Portland, an amphibious dock ship, will be in sight of the splash, ready to secure the craft and tow it to the “well deck ” flooded from the Navy ship.

Once the deck doors are closed, the water will be pumped out, leaving Orion in a custom stand, protecting its heat shield, for the return trip to Naval Base San Diego.

But first, the recovery team will stay put for up to two hours while engineers collect data on how the heat from reentry soaked into the spacecraft and what effects, if any, it might have on temperature from the crew cabin.

“We’re on track to have a fully successful mission with some bonus goals we’ve hit along the way,” Sarafin said. “And on entry day, we will accomplish our priority goal, which is to demonstrate the vehicle in lunar reentry conditions.”