NASA studies unexpected performance of Orion’s heat shield ahead of crew mission – Ars Technica

Enlarge / NASA’s Orion spacecraft descends toward the Pacific Ocean after a successful mission in December.


About three months have passed since NASA’s Orion spacecraft splashed down in the Pacific Ocean after a flight to the Moon and back. At the time, the space agency said the Artemis I mission had successfully met its goals, paving the way for humans to follow suit.

This week, after carefully reviewing data from the Artemis I mission since the splashdown, space agency officials reiterated that while there were a few minor problems with the flight, overall it boosted confidence. As a result, NASA’s chief of human deep space exploration, Jim Free, said the agency is targeting “late November” 2024 for the Artemis II mission.

During this flight, four astronauts – probably including a Canadian – will spend a little more than a week in deep space. After checking the performance of Orion in low Earth orbit, the spacecraft will fly into what is known as a “free return orbit” around the Moon, which will bring them as close as 7,500 km to the Moon’s surface before turning back.

Amid much fanfare, NASA expects to name the crew of the Artemis II mission later this spring. They will be the first humans to fly beyond low-Earth orbit in more than 50 years, since the end of the Apollo Moon program in December 1972. If NASA succeeds in the Artemis II mission, it will lay the foundation for a manned moon lands in the second half of the 2020s.

Orion performance

Perhaps the most notable topic discussed during the press conference was the performance of Orion’s heat shield, which protects the spacecraft as it reenters Earth’s atmosphere at high speed. This represented one of the key tests during Artemis I, as vehicles returning from the Moon do so at a speed of about 40,000 km/h, which is about 30 percent faster than a vehicle typically returning from low orbit in The earth.

“During inspections, there were more variations across the heat shield than we expected,” said Howard Hu, the Orion program manager for NASA. “Some of the charred material dissipated differently than what our computer models and our soil tests predicted. More of this charred material was released during reentry than we expected.”

A heat shield like that on Orion, and most other space-return vehicles, is designed to burn off or remove as it heats up during its flight through the atmosphere. This ablative material in the base of the spacecraft protects the vehicle itself and any crew inside from the extremely hot conditions outside.

In this case, there was still plenty of margin in the ablative material on Orion, meaning that the unexpected behavior seen in the heat shield poses no risk to the spacecraft. But NASA wants to refine its modeling of this behavior so it has a good handle on what to expect during future missions.

“When we have unexpected behavior, we will drive to find a root cause,” Hu said. “I would say we will be very cautious and make sure we do our due diligence. Vigilance is very important to us as we fly crew going forward.”

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