Artemis II Re-entry and Splashdown: Orion Integrity Returns

Why did NASA fly the Orion capsule Integrity back through the atmosphere on a steeper, shorter path than the one used on the uncrewed Artemis I flight? The answer sits in the heat shield, and it shaped the final hours of Artemis II, the mission that carried Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen of the Canadian Space Agency around the Moon. They launched from Kennedy Space Center on April 1 and splashed down in the Pacific off the coast of San Diego at 7:07 p.m. Central time (5:07 p.m. Pacific) on April 10, after a journey of 694,481 miles.

What went wrong with the heat shield on Artemis I

When the uncrewed Artemis I capsule splashed down in November 2022, recovery teams found big chunks missing from its heat shield. Everyday Astronaut host Tim Dodd explained the background: the Apollo-era shield was built from a honeycomb of thousands of small cells, each filled by hand with Avcoat ablative material, one at a time, which took hundreds of hours. For Orion, NASA moved to larger machined blocks of the material.

Artemis I also flew a skip entry. The capsule dipped into the atmosphere to shed energy, skipped back out, and dipped in again before splashing down. The offset center of mass lets the capsule be rolled to go deeper into the atmosphere or climb back out, which allows precise targeting of the landing area. According to the explanation given on the stream, the pause between the two dips let molten pockets of unburnt material trapped beneath the shield outgas, forming cracks and pits and deteriorating parts of the shield. NASA commentary noted unexpected loss of some of the charred Avcoat.

The host said that even if crew had been aboard Artemis I, and even if the shield had burned all the way through, which it did not, they would very likely have been safe. NASA and Lockheed Martin decided to fly the same kind of shield again with a changed profile.

The Artemis II entry profile

NASA commentary described the difference: Artemis I exposed its heat shield to about 20 minutes of peak heating, while Artemis II would reach a downrange distance of 1,700-plus nautical miles from entry interface in just 14 minutes, using a steeper angle of attack to protect the shield from excessive heat loads. Artemis III and beyond are expected to have a differently designed shield that allows the skip profile.

The host described the trade-off as a bigger recovery area and higher peak heating but a lower total heat load, and said he had trouble keeping the two terms straight. The shield was also described as having been tested in the lab after the Artemis I findings, where the root cause of the pocking was investigated.

The final hour

The crew suited up again for entry. Leak checks were completed, and seats three and four were being strapped in as Wiseman reported status. As the capsule passed over the southwest coast of Australia, the commentary put it at an altitude of about 7,600 nautical miles.

A hot fire of the reaction control thrusters preceded separation. Two enabled propulsion cautions appeared during that firing: multiple pressure sensors on each string diverged slightly, and the team judged the limits to be set tight and chose to suppress the messages rather than inhibit them. Wiseman concurred with "suppress, not inhibit." GPS data was initially not acquired, and flight controllers noted it would be good to have but was not necessary.

The crew module separated from the European service module, with the pyros armed beforehand. A 19-second firing of the thrusters, a change in velocity of 9.9 feet per second, tilted the aft end upward to set the final angle of attack. Wiseman reported the moon looking a little smaller than the day before.

Blackout and peak speed

Entry interface came at 400,000 feet with the capsule traveling 34,800 feet per second, roughly 25,000 mph. Commentary said peak speed would be reached about 10 seconds after entry interface, with temperatures around the spacecraft rising to about 4,000 to 5,000 degrees Fahrenheit. The host said these were the fastest speeds any humans had traveled in 54 years.

A communications blackout of about six minutes began at 6:53 and 54 seconds p.m. Central time. The host explained that the air heats because it is compressed ahead of the heat shield rather than from friction, becoming plasma that radio signals cannot pass through. Aircraft near the splashdown zone, including a G5 and a WB-57, and Navy helicopters had visual contact on the capsule through the blackout. When voice returned, Houston called "Integrity, Houston, com check post blackout," and Wiseman answered that they had Houston loud and clear. Houston told the crew their trajectory was nominal and recovery teams had visual.

Parachutes and splashdown

The parachute sequence was described in advance: three forward bay cover parachutes pull the cover off, two drogue parachutes slow and stabilize the capsule, and three pilot parachutes pull out the three main parachutes, each 116 feet in diameter. The parachutes were to slow Integrity from nearly 33 times the speed of sound to a gentle 19 mph at splashdown.

In the event, the crew reported two good drogues out the window, then three good main parachutes with good reefing and a good descent rate. A search and recovery beacon was activated, and cabin pressure showed no need for hydrazine checks. Splashdown was confirmed at 7:07 p.m. Central. The landing support officer reported the capsule was in the stable one configuration, upright, and called it a bullseye splashdown. Five helium-inflated airbags, the crew module uprighting system, were deployed to maintain that orientation. Wiseman reported four green crew members, meaning all four were in good condition.

Recovery

With calm seas, the plan was a power-down about 15 minutes after splashdown, followed by Navy teams approaching to erect an inflatable raft called the front porch beside the hatch. The crew would then be hoisted one at a time by two Navy helicopters. The recovery vessel was the USS John P. Murtha. Everyday Astronaut also explained why the Pacific was chosen: a short fall in the Atlantic could end on land, which the capsule is not designed for, while the recovery ships are based in San Diego.