Artemis II crew faces risky reentry before splashdown on Earth

The four astronauts of Artemis II, who have circled the moon and traveled farther in space than any human in history, will finish their epic 10-day voyage on April 10 with a risky high-speed reentry into Earth’s atmosphere, including reaching temperatures of up to 3,000 degrees Fahrenheit.

The crew’s Orion capsule, which they’ve named Integrity, will splash down off the San Diego coast shortly after 5 p.m. PT.

The USS John P. Murtha (LPD-26), an amphibious transport dock ship, will recover astronauts Reid Wiseman, Victor Glover and Christina Koch of NASA, and Jeremy Hansen of the Canadian Space Agency, at sea.

But to reach the Pacific, the capsule must first execute a high-altitude maneuver called a “skip-entry” trajectory to reduce speed as it hits the atmosphere at roughly 25,000 mph.

How will Orion return to Earth?

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The Artemis II mission began with a liftoff from Cape Canaveral on April 1. Its lunar flyby was on April 6 and the Orion capsule began using the moon's gravity as a slingshot on its trajectory back toward Earth.

To start reentry, the capsule will begin maneuvering 75 miles above the Earth for its final descent back to the surface. Basic steps for a safe return:

• A final return trajectory correction burn fine-tunes Orion’s course to make sure it’s on the right path for splashdown.
• The crew stows equipment and puts seats into place.
• The crew puts on their spacesuits.
• About 20 minutes before reentry, the crew module − the capsule − separates from the service module. This exposes the capsule’s heat shield, which protects the spacecraft and crew from the intense heat.

Why does heat build up during reentry?

Reentry begins at what’s called Entry Interface, an altitude of about 400,000 feet. The atmosphere acts as a brake as it gets denser. The spacecraft, moving at speeds up to 25,000 mph, builds up heat by creating shock waves. Those waves compress and superheat gas in the atmosphere to temperatures of 3,000 degrees Fahrenheit or more.

Within seconds, superheated charged particles known as plasma build up around the spacecraft, causing a short communications blackout. The recovery teams wait at a holding point until GPS readings are restored and the capsule’s position is determined.

How does the Artemis heat shield work?

The reentry will naturally focus attention on the capsule’s heat shield, the largest ever built for astronauts, NASA says.

It serves as a heat-protection feature, but it also provides a large drag surface to allow the capsule to brake more efficiently.

The heat shield is made of Avcoat, an ablative material that burns away bit by bit, which carries heat away from the capsule. It was used on Apollo capsules, but it’s applied differently to Artemis by using tiles or blocks that are painstakingly fitted together.

• 26,500 feet: The protective cover of the capsule’s forward bay is jettisoned to allow a series of three sets of parachutes to deploy.
• 25,000 feet: Two drogue parachutes (23 feet wide) deploy, slowing descent to about 307 mph.
• 9,500 feet: Three pilot parachutes (11 feet wide) deploy to help pull out the main parachutes.
• 9,000 feet: Three main parachutes (116 feet wide) deploy, slowing descent to about 17 mph.
• The capsule splashes down in the Pacific.

After splashdown, five orange airbags will inflate around the top of the spacecraft and flip the capsule upright. The crew will exit the craft within two hours onto a U.S. Navy recovery vessel.

Navy divers will retrieve the spacecraft by attaching devices between it and the recovery ship. Teams will bring the capsule aboard the ship and secure it for its trip to shore.

Where will Orion splash down?

The Orion capsule is scheduled to make a water landing at approximately 8:07 p.m. ET in the Pacific Ocean off the coast of San Diego.

CONTRIBUTING Eric Lagatta, USA TODAY

SOURCE USA TODAY Network reporting and research; NASA; Reuters; Lockheed Martin