The Artemis 1 spacecraft approaches Earth for Sunday’s splashdown

Capping off a 25-day journey around the moon, NASA’s Artemis 1 spacecraft approached Earth on Saturday, on track for a 25,000-mph reentry on Sunday that will subject the unmanned capsule to a hellish 5,000-degree heat. before landing off Baja California.

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 overriding goal for a reason,” said mission manager Mike Safarin.

“There is no arc jet or aerothermal facility here on Earth that can replicate hypersonic reentry with a heat shield of this size,” he said. “And it’s a brand 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.”

On Nov. 28, halfway through the Artemis 1 mission, a camera on one of the Orion spacecraft’s four solar wings captured this iconic view of Earth and the blue-and-white moon (bottom right). / Credit: NASA

Launched November 16th During the maiden flight of NASA’s massive new Space Launch System rocket, the unmanned Orion capsule was propelled out of Earth orbit and onto the moon for an exhaustive series of tests, testing its propulsion, navigation, power and deep space environment computer.

While flight controllers ran into as-yet unexplained anomalies with its power system, initial “amusements” with its star trackers, and degraded performance from a phased array antenna, the Orion spacecraft and its service module built by the European Space Agency worked well overallachieving virtually all of their major goals up to this point.

“We have collected a huge amount of data characterizing system performance from the fuel system, propulsion, CNG (Guidance, Navigation and Control) and so far the flight control team has downlinked over 140 gigabytes of engineering data and of images,” said Jim Geffre, vehicle integration manager at Orion.

The Orion spacecraft followed a trajectory that included a close lunar flyby and subsequent engine burn to reach the planned area

The Orion spacecraft followed a trajectory that included a close lunar flyby and subsequent engine burn to reach the planned area

The team is already analyzing that data “to help not only understand performance on Artemis 1, but also for all subsequent missions,” he said.

Hopefully, NASA plans to follow up on 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 will follow in 2025-26 when NASA says the first woman and the next man they will set foot on the lunar surface.

The unmanned Artemis 1 capsule went through half an orbit around the moon that took it farther from Earth — 268,563 miles — than any previous human spacecraft. On Monday, two critical firings of its main engine initiated a low-altitude lunar flyby that, in turn, put the craft on course for Sunday’s crash.

NASA originally planned to fly the vessel west of San Diego, but an expected cold front bringing higher winds and rougher seas prompted mission leaders to move the landing site south approximately 350 miles. Splashdown is now expected south of Guadalupe Island, approximately 200 miles west of Baja California.

Approaching nearly from the south, the Orion spacecraft, traveling at 32 times the speed of sound, is expected to slam back into the perceptible atmosphere at an altitude of 400,000 feet, or about 76 miles, at 12:20 p.m. EST.

The Orion spacecraft will fly in an unusual way

The Orion spacecraft will fly in an unusual way

NASA planners have devised a unique “jump-in” profile that will make Orion leap across the upper atmosphere like a flat stone skipping over calm water. Orion will dive from 400,000 feet to about 200,000 feet in just two minutes, then ascend to about 295,000 feet before resuming its computer-guided fall to Earth.

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

After another two and a half minutes of communications blackout during its second drop into the lower atmosphere, the spacecraft will continue to decelerate as it approaches the targeted landing site, slowing to about 650 mph, roughly the speed of sound, approximately 15 minutes after the start of the recording.

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

An Orion mockup is carried into the flooded well deck of a Navy amphibious dockside vessel during training to prepare for Sunday's splashdown and recovery of the current Artemis 1 spacecraft following its 1.4 million test flight miles around the moon.  / Credit: NASA

An Orion mockup is carried into the flooded well deck of a Navy amphibious dockside vessel during training to prepare for Sunday’s splashdown and recovery of the current Artemis 1 spacecraft following its 1.4 million test flight miles around the moon. / Credit: NASA

Estimated mission duration: 25 days 10 hours 52 minutes, covering 1.4 million miles since liftoff on November 16.

NASA and Navy recovery crews aboard the USS Portland, an amphibious dock ship, will be standing by ahead of ditching, ready to secure the craft and tow it into the Navy ship’s flooded “well deck” .

Once the bridge gates close, the water will be pumped out, leaving Orion on a custom stand, protecting its heat shield, for the return journey to Naval Base San Diego.

But first, the recovery team will stand by for up to two hours while engineers gather data on how the heat from reentry has penetrated the spacecraft and what effect, if any, it might have on crew cabin temperature.

“We are on track to have a fully successful mission with some bonus objectives we have achieved along the way,” Sarafin said. “And on entry day, we will accomplish our priority goal, which is to demonstrate the vehicle under lunar reentry conditions.”

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