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 practically 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 defend. Because the capsule streaked again into Earth’s ambiance on the finish of the mission, the warmth defend ablated, or burned off, in a distinct method than predicted by pc fashions.
Extra of the charred materials than anticipated got here off the warmth defend throughout the Artemis I reentry, and the way in which it got here off was considerably uneven, NASA officers stated. Orion’s warmth defend is product of a fabric referred to as Avcoat, which is designed to burn off because the spacecraft plunges into the ambiance 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 ambiance from low-Earth orbit.
Regardless of warmth defend problem, 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 improvement 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 defend problem. Managers wish to make sure they perceive the trigger earlier than continuing with Artemis II, which is able to ship astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day flight across the far aspect of the Moon.
This would be the first time people fly close to the Moon because the 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 defend problem.
“We’re nonetheless in the midst of our investigation on the efficiency of the warmth defend from Artemis I,” Kshatriya stated Friday in a gathering with a committee of the NASA Advisory Council.
Engineers have carried out sub-scale warmth defend checks in wind tunnels and arc jet services 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 modifications to the warmth defend already put in on the Orion spacecraft for Artemis II, however have not dominated it out. A redesign or modifications to the Orion warmth defend on Artemis II would most likely delay the mission by at the least a 12 months.
As a substitute, engineers are analyzing all the doable trajectories the Orion spacecraft might fly when it reenters the ambiance on the finish of the Artemis II mission. On Artemis I, Orion flew a skip reentry profile, the place it dipped into the ambiance, skipped again into house, after which made a closing descent into the ambiance, kind 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 using 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 accessible referred to as a ballistic entry, during which the spacecraft would fly via the ambiance unguided.
The charred materials started flying off the warmth defend within the first part of the skip reentry. Engineers are taking a look at how the skip reentry profile affected the efficiency of the Orion warmth defend. NASA desires to grasp how the Orion warmth defend would carry out throughout every of the doable reentry trajectories for Artemis II.
“What now we have the evaluation groups off doing is saying, ‘OK, unbiased of what the constraints are going to be, what can we tolerate?” Kshatriya stated.
As soon as officers perceive the reason for the warmth defend charring, engineers will decide what sort of trajectory Artemis II must fly on reentry to reduce threat to the crew. Then, managers will take a look at constructing what NASA calls flight rationale. Primarily, this can be a means of convincing themselves the spacecraft is protected to fly.
“Once we sew all of it collectively, we’ll both have flight rationale or we received’t,” Kshatriya stated.
Assuming NASA approves the flight rationale for Artemis II, there shall be further discussions about how to make sure Orion warmth shields are protected to fly on downstream Artemis missions, which could 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 Middle. The crew and repair modules for Artemis II have been mated collectively earlier this 12 months, and the complete Orion spacecraft is now inside a vacuum chamber for environmental testing.
