NASA
NASA officers declared the Artemis I mission profitable in late 2021, and it is arduous to argue with that evaluation. The Area Launch System rocket and Orion spacecraft carried out almost flawlessly on an unpiloted flight that took it across the Moon and again to Earth, setting the stage for the Artemis II, this system’s first crew mission.
However one of many issues engineers noticed on Artemis I that did not fairly match expectations was a difficulty with the Orion spacecraft’s warmth protect. Because the capsule streaked again into Earth’s environment on the finish of the mission, the warmth protect ablated, or burned off, in a distinct method than predicted by laptop fashions.
Extra of the charred materials than anticipated got here off the warmth protect through the Artemis I reentry, and the best way it got here off was considerably uneven, NASA officers stated. Orion’s warmth protect is made from a fabric referred to as Avcoat, which is designed to burn off because the spacecraft plunges into the environment at 25,000 mph (40,000 km per hour). Getting back from the Moon, Orion encountered temperatures as much as 5,000° Fahrenheit (2,760° Celsius), hotter than a spacecraft sees when it reenters the environment from low-Earth orbit.
Regardless of warmth protect challenge, the Orion spacecraft safely splashed down within the Pacific Ocean. Engineers found the uneven charring throughout post-flight inspections.
No solutions but
Amit Kshatriya, who oversees growth for the Artemis missions in NASA’s exploration division, stated Friday that the company remains to be searching for the basis reason for the warmth protect challenge. Managers wish to make sure they perceive the trigger earlier than continuing with Artemis II, which can ship astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day flight across the far facet of the Moon.
This would be the first time people fly close to the Moon for the reason that final Apollo mission in 1972. In January, NASA introduced a delay within the launch of Artemis II from late 2024 till September 2025, largely because of the unresolved investigation into the warmth protect challenge.
“We’re nonetheless in the course of our investigation on the efficiency of the warmth protect from Artemis I,” Kshatriya stated Friday in a gathering with a committee of the NASA Advisory Council.
Engineers have carried out sub-scale warmth protect exams in wind tunnels and arc jet amenities to higher perceive what led to the uneven charring on Artemis I. “We’re getting near the ultimate reply when it comes to that trigger,” Kshatriya stated.
NASA officers beforehand stated it’s unlikely they might want to make adjustments to the warmth protect already put in on the Orion spacecraft for Artemis II, however have not dominated it out. A redesign or modifications to the Orion warmth protect on Artemis II would in all probability delay the mission by at the least a yr.
As a substitute, engineers are analyzing all the doable trajectories the Orion spacecraft might fly when it reenters the environment on the finish of the Artemis II mission. On Artemis I, Orion flew a skip reentry profile, the place it dipped into the environment, skipped again into area, after which made a closing descent into the environment, type of like a rock skipping throughout a pond. This profile permits Orion to make extra exact splashdowns close to restoration groups within the Pacific Ocean and reduces g-forces on the spacecraft and the crew driving inside. It additionally splits up the warmth load on the spacecraft into two phases.
The Apollo missions flew a direct reentry profile. There may be additionally a reentry mode out there referred to as a ballistic entry, through which the spacecraft would fly by the environment unguided.
The charred materials started flying off the warmth protect within the first section of the skip reentry. Engineers are how the skip reentry profile affected the efficiency of the Orion warmth protect. NASA desires to know how the Orion warmth protect would carry out throughout every of the doable reentry trajectories for Artemis II.
“What we’ve the evaluation groups off doing is saying, ‘OK, impartial of what the constraints are going to be, what can we tolerate?” Kshatriya stated.
As soon as officers perceive the reason for the warmth protect charring, engineers will decide what sort of trajectory Artemis II must fly on reentry to reduce threat to the crew. Then, managers will have a look at constructing what NASA calls flight rationale. Basically, this can be a technique of convincing themselves the spacecraft is secure to fly.
“After we sew all of it collectively, we’ll both have flight rationale or we gained’t,” Kshatriya stated.
Assuming NASA approves the flight rationale for Artemis II, there shall be extra discussions about how to make sure Orion warmth shields are secure to fly on downstream Artemis missions, which can have higher-speed reentry profiles as astronauts return from landings on the Moon.
Within the meantime, preparations on the Orion spacecraft for Artemis II proceed at NASA’s Kennedy Area Heart. The crew and repair modules for Artemis II had been mated collectively earlier this yr, and all the Orion spacecraft is now inside a vacuum chamber for environmental testing.
