The four astronauts who flew around the moon on NASA’s Artemis II mission are nearly home, but one of the most dangerous and nerve-racking parts of the mission is still ahead.NASA astronauts Reid Wiseman, Christina Koch and Victor Glover and Canadian astronaut Jeremy Hansen are set to return to Earth on Friday evening after 10 days in space.Their Orion capsule is scheduled to begin plunging through the atmosphere at around 7:53 p.m. ET on a fiery journey expected to last less than 15 minutes. If all goes well, the mission will culminate in a splashdown in the Pacific Ocean at 8:07 p.m. ET off San Diego.AdvertisementAdvertisement“It’s 13 minutes of things that have to go right,” Jeff Radigan, NASA’s Artemis II flight director, said Thursday at a news briefing.Re-entry is always one of the riskiest parts of spaceflight, as vehicles can be exposed to temperatures of around 5,000 degrees Fahrenheit as they streak through the atmosphere. But that is particularly true for Artemis II, because the Orion spacecraft’s heat shield — the critical layer of thermal protection at the bottom that protects astronauts from extreme temperatures — has known flaws in its design.This mission is the first time the capsule is carrying a crew.After the Artemis I mission in 2022 — an uncrewed test flight of the Space Launch System rocket and Orion capsule — NASA found unexpected damage to the spacecraft’s heat shield.NASA’s Orion spacecraft was recovered at the end of the Artemis I test flight and taken to Kennedy Space Center in Florida, where its heat shield was removed and inspected. (NASA)(NASA)An agency investigation later found that part of the heat shield’s material had cracked during atmospheric re-entry, “causing some charred material to break off in several locations.” The investigation determined that gases did not vent properly in the heat shield’s outer material, allowing pressure to accumulate, which caused the observed damage.Images show heat shield damage sustained during Artemis I. (NASA)(NASA)Because of those issues, NASA will modify the heat shield design for future Artemis flights. The Orion spacecraft used for those missions will feature a more permeable layer of outer material. But for Artemis II, the capsule had already been built and assembled when NASA learned of the damage sustained during Artemis I.AdvertisementAdvertisementSo, rather than redo the heat shield, NASA came up with a modified path for the capsule’s re-entry to minimize risk to the astronauts. Ordinarily, before it begins its final descent, the O …
