When Artemis II returns to Earth on Friday, it will hit the atmosphere at about 75 miles above the Pacific Ocean at around 24,000MPH, which is fast enough to fly from Los Angeles to New York in about 6 minutes.
The temperatures will climb to about 5,000 degrees, which is about half as hot as the sun. The four astronauts on board are Commander Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen. They are counting on the heat shield to keep them safe. On the way down, a parachute-assisted splashdown is expected at 8:07 pm ET.
The crew is confident, despite major problems with the heat shield, which was used during the unpiloted Artemis I test flight in 2022. Agency managers decided to order a different heat shield design for downstream Artemis missions. But an identical one for Artemis I was already installed, and putting the new design in would have delayed the trip by 18 months or more.
“They did a tremendous amount of research, a lot of groundbreaking research in some facilities we never used before, and they discovered the root cause, “ Wiseman said. During the Artemis I mission, the unpiloted capsule followed a planned “skip” trajectory. After the initial dip, it went into the upper atmosphere and skipped back out again before making its final descent to splashdown.
Despite the heat shield damage observed after the flight, Artemis I was successful during reentry. It landed on target, and if anyone was on board, they would have had no problems.
Upon inspection after Orion’s recovery, engineers noted unexpected variations in the appearance of the heat shield avcoat. Portions of the char layer wore away differently than NASA engineers predictied/
Entry heating is what makes the Avcoat’s outer char layer preamble enough to allow gas to escape.
Apollo engineers were aware of the Avcoat issue and designed that program’s heat shields accordingly.
In a letter to NASA administrator, Camarda wrote that history shows accidents occure when orgamizations convince themselves they understand the problems they do not.
