Artemis II’s Next Challenge: The Heat and High Stakes of a Fiery Re-Entry
The Orion spacecraft’s heat shield will be tested in an intense re-entry to the Earth’s atmosphere
The Artemis II mission crew is returning to Earth Friday evening, facing a critical re-entry after successfully traveling around the moon.
During the uncrewed Artemis I mission in 2022, the Orion spacecraft’s heat shield chipped off in more than 100 locations.
NASA opted for a steeper re-entry angle for Artemis II to mitigate the risk, though some former employees urged another uncrewed test flight.
The crew of NASA’s Artemis mission made it around the moon. One of their biggest challenges still lies ahead: navigating the intense heat of re-entry to Earth’s atmosphere.
During descent, the Orion capsule where the astronauts have been living and working will slam into the planet’s atmosphere, exposing it to a firestorm reaching 5,000 degrees. The vehicle must make it through in order for the crew to do the same.
Re-entry is slated to intensify about 7:30 p.m. ET on Friday evening. If all goes well, Artemis II’s Orion module will splash down about 40 minutes later in the Pacific Ocean, near San Diego. A recovery team with Navy divers is set to swiftly retrieve them.
The mission’s last chapter carries some of the highest stakes. During the previous, uncrewed Artemis mission, the Orion craft’s heat shield didn’t perform as expected, with protective material on the device chipping off. The problem delayed the Artemis II launch as engineers tried to understand and mitigate the risks.
As astronauts Reid Wiseman, Victor Glover, Christina Koch and Jeremy Hansen return to Earth, their vehicle will briefly be speeding along at close to 35,000 feet per second. Each will be kept cool in a pressurized flight suit.
Mission controllers expect the Artemis crew will be silent during their return, with Wiseman and Glover monitoring vehicle performance.
An awareness of the stakes for anyone who travels into orbit has been baked into NASA’s efforts since its earliest days. In 1961, President John F. Kennedy said he wanted to both land a man on the moon before the end of that decade—and bring “him safely to the Earth.”
The missions where crews didn’t make it home—the 1986 Challenger space-shuttle disaster and the Columbia shuttle failure 17 years later—killed 14 crew members between them, and still loom large at the agency.
“I’ve actually been thinking about entry since April 3, 2023, when we got assigned to this mission,” Glover said during a Wednesday night press briefing. “We have to get back.”
Chipped shield
During the first Artemis mission in 2022, the Orion vehicle flew 1.4 million miles over nearly a month without a crew, testing its capabilities for future missions. But it was the minutes that Orion spent hurtling into the Earth’s atmosphere that alarmed NASA.
Chunks of Orion’s heat shield chipped off in more than 100 locations, raising fears that a repeat could endanger any astronauts inside.
Orion’s heat shield is installed on the underside of the vehicle’s crew module, spanning almost 17 feet in diameter. It is made up of blocks of Avcoat—a material made of silica fibers that is supposed to melt off during the return maneuver, transferring heat away from the vehicle.
After research and internal deliberations, NASA opted to bring Orion back to Earth at a steeper angle for the Artemis II mission. The trajectory will bring the vehicle into the atmosphere and briefly regain altitude before its final descent. The workaround is intended to limit a period when gases accumulated inside the shield during the first mission, leading to the charring.
The plan was endorsed by NASA Administrator Jared Isaacman and gained widespread support inside the agency.
“We’ve done the work we need to. I have full confidence in the team,” Amit Kshatriya, NASA’s associate administrator, said Thursday afternoon.
Some former employees believe the agency should have flown another mission without astronauts to test the heat shield’s performance on the new re-entry path, rather than try it for the first time in flight with people on board.
“There’s no reason to have a crew on this,” said Dan Rasky, who worked on re-entry systems before retiring from NASA last year.
He said he brought up a potential alternative to Orion’s current shield before leaving the agency, pointing to the kind of shield SpaceX uses for its Dragon vehicles.
Assessing risk
After Artemis I, NASA convened teams to analyze what happened with the heat shield. They conducted numerous tests on the ground to determine why the material chipped off. A review board agreed with the agency’s findings.
At a January meeting at NASA’s headquarters, agency leaders and engineers hashed out the situation, with one official saying the heat shield wasn’t in an ideal state.
They took questions from some former agency employees skeptical of their plans and their understanding of why the heat shield charred during Artemis I, while laying out the rationale proceeding with the next mission.
Wiseman, a retired Naval aviator serving as commander of the Artemis II mission, said in an interview last September that he initially was skeptical about NASA’s plan to use a new return path to account for the heat-shield problems.
He later came around, recalling a briefing that laid out how the modified re-entry would contain the risks.
“I went into that thinking they were going to change the heat shield,” Wiseman said. “But by the end of that briefing, I was like, we were actually going to apply this trajectory. We actually can mount this thing.”
On Friday, Wiseman and his crewmates will.