Written by Joey Roulette and Steve Gorman

(Reuters) – NASA’s uncrewed Orion capsule hurtled through space Sunday on the final leg of its journey around the moon and back, concluding the inaugural mission of the Artemis lunar program 50 years to the day after the last Apollo moon landing.

The gumdrop-shaped Orion capsule, carrying a simulated crew of three mannequins attached to sensors, was scheduled to parachute into the Pacific Ocean at 9:39 a.m. PST (1739 GMT) near Guadalupe Island, off the Baja Peninsula. Mexican California.

Orion was nearing the end of its 25-day mission less than a week after it passed about 79 miles (127 km) above the moon on a lunar lunar excursion and about two weeks after it reached the farthest point in space, nearly 270,000 miles (434,000 miles). (500 km) from Earth.

After jettisoning the service module housing its main rocket system, the capsule was expected to re-enter Earth’s atmosphere at 24,500 mph (39,400 kph) — more than 30 times the speed of sound — for a fiery 20-minute dive into the ocean. .

Orion lifted off Nov. 16 from Kennedy Space Center in Cape Canaveral, Florida, atop NASA’s next-generation Space Launch System (SLS), now the world’s most powerful rocket and the largest NASA has built since Apollo’s Saturn V. era.

The first SLS-Orion flight kicked off the Apollo program, Artemis, which aims to return astronauts to the lunar surface this decade and establish a sustainable base there as a jumping-off point for future human exploration of Mars.

Serendipitously, the return of Artemis I to Earth unfolded on the 50th anniversary of the Apollo 17 moon landings by Gene Cernan and Harrison Schmitt on December 11, 1972. They were the last of the 12 NASA astronauts to walk on the Moon during totality. of the six Apollo missions beginning in 1969.

Hit a penny with a soccer ball

Reentry marks the most critical phase of Orion’s flight, testing whether the newly designed heat shield will withstand atmospheric friction expected to raise temperatures outside the capsule to nearly 5,000 degrees Fahrenheit (2,760 degrees Celsius).

“It’s our number one target,” Mike Sarafin, NASA’s Artemis 1 mission manager, said at a news briefing last week. “There is no arc jet or atmospheric thermal facility here on Earth capable of replicating hypersonic reentry with a heat shield of this size.”

It will also test the advanced guidance and propulsion systems used to guide the capsule from the moon to the appropriate re-entry point and through to landing, while keeping the spacecraft at exactly the right angle to avoid burn-up.

“It’s basically like throwing a soccer ball 300 yards and hitting a penny,” said Eric Kaufman, Orion Propulsion senior manager at Lockheed Martin Corp. (NYSE:), which built Orion under a contract with NASA, told Reuters.

The navigation and internal control system commands 12 onboard thrusters, located in recessed positions along the base of the capsule, to fire bursts of fuel as needed to keep the capsule properly oriented and on course, he said.

hotter and faster

The heat, speed, and forces exerted on Orion upon its return from the Moon would exceed those endured by spacecraft leading to more routine descents from the International Space Station (ISS) or other flights from low Earth orbit.

In another new development, Orion is programmed to employ a new “skip entry” descent in which the capsule briefly dips into the top of the atmosphere, flies out and reenters – a braking maneuver that also provides more control to steer the vehicle closer to its intended target.

NASA officials have stressed the experimental nature of the Artemis I mission, which marks the first launch of Boeing (NYSE: Co-built SLS) and the first combined with Orion, which previously flew a short two-orbit test launch on a smaller Delta IV. Rocket in 2014.

Although the capsule experienced some unexpected communications outages and an electrical problem during its trip around the Moon, NASA has given high marks to both SLS and Orion’s performance so far, boasting that it has exceeded the US space agency’s expectations.

If Artemis I is deemed successful, a manned Artemis II flight around the Moon and back could come as early as 2024, followed in a few more years by the first lunar landing of the Artemis program, one of them being a woman, with Artemis III.

Compared to Apollo, born of the Cold War-era U.S.-Soviet space race, Artemis is a more science-based, large-scale mover, enlisting commercial partners like Elon Musk’s SpaceX and space agencies in Europe, Canada and Japan.

It also marked a major turning point for NASA, redirecting the human spaceflight program beyond low-Earth orbit after decades of focus on the space shuttles and the International Space Station.