orion

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NASA says Orion’s heat shield is good to go for Artemis II—but does it matter?

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“We have since determined that while the capsule was dipping in and out of the atmosphere, as part of that planned skip entry, heat accumulated inside the heat shield outer layer, leading to gases forming and becoming trapped inside the heat shield,” said Pam Melroy, NASA’s deputy administrator. “This caused internal pressure to build up and led to cracking and uneven shedding of that outer layer.”

An independent team of experts concurred with NASA’s determination of the root cause, Melroy said.

NASA Administrator Bill Nelson, Deputy Administrator Pam Melroy, Associate Administrator Jim Free, and Artemis II Commander Reid Wiseman speak with reporters Thursday in Washington, DC. Credit: NASA/Bill Ingalls

Counterintuitively, this means NASA engineers are comfortable with the safety of the heat shield if the Orion spacecraft reenters the atmosphere at a slightly steeper angle than it did on Artemis I and spends more time subjected to higher temperatures.

When the Orion spacecraft climbed back out of the atmosphere during the Artemis I skip reentry, a period known as the skip dwell, NASA said heating rates decreased and thermal energy accumulated inside the heat shield’s Avcoat material. This generated gases inside the heat shield through a process known as pyrolysis. 

“Pyrolysis is just burning without oxygen,” said Amit Kshatriya, deputy associate administrator of NASA’s Moon to Mars program. “We learned that as part of that reaction, the permeability of the Avcoat material is essential.”

During the skip dwell, “the production of those gases was higher than the permeability could tolerate, so as a result, pressure differential was created. That pressure led to cracks in plane with the outer mold line of the vehicle,” Kshatriya said.

NASA didn’t know this could happen because engineers tested the heat shield on the ground at higher temperatures than the Orion spacecraft encountered in flight to prove the thermal barrier could withstand the most extreme possible heating during reentry.

“What we missed was this critical region in the middle, and we missed that region because we didn’t have the test facilities to produce the low-level energies that occur during skip and dwell,” Kshatriya said Thursday.

During the investigation, NASA replicated the charring and cracking after engineers devised a test procedure to expose Avcoat heat shield material to the actual conditions of the Artemis I reentry.

So, for Artemis II, NASA plans to modify the reentry trajectory to reduce the skip reentry’s dwell time. Let’s include some numbers to help illustrate the difference.

The distance traveled by Artemis I during the reentry phase of the mission was more than 3,000 nautical miles (3,452 miles; 5,556 kilometers), according to Kshatriya. This downrange distance will be limited to no more than 1,775 nautical miles (2,042 miles; 3,287 kilometers) on Artemis II, effectively reducing the dwell time the Orion spacecraft spends in the lower heating regime that led to the cracking on Artemis I.

NASA’s inspector general report in May included new images of Orion’s heat shield that the agency did not initially release after the Artemis I mission. Credit: NASA Inspector General

With this change, Kshatriya said NASA engineers don’t expect to see the heat shield erosion they saw on Artemis I. “The gas generation that occurs during that skip dwell is sufficiently low that the environment for crack generation is not going to overwhelm the structural integrity of the char layer.”

For future Orion spaceships, NASA and its Orion prime contractor, Lockheed Martin, will incorporate changes to address the heat shield’s permeability problem.

Waiting for what?

NASA officials discussed the heat shield issue, and broader plans for the Artemis program, in a press conference in Washington on Thursday. But the event’s timing added a coat of incredulity to much of what they said. President-elect Donald Trump, with SpaceX founder Elon Musk in his ear, has vowed to cut wasteful government spending.

NASA says Orion’s heat shield is good to go for Artemis II—but does it matter? Read More »

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After critics decry Orion heat shield decision, NASA reviewer says agency is correct

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“If this isn’t raising red flags out there, I don’t know what will.”

NASA’s Orion spacecraft, consisting of a US-built crew module and European service module, is lifted during prelaunch processing at Kennedy Space Center in 2021. Credit: NASA/Amanda Stevenson

Within hours of NASA announcing its decision to fly the Artemis II mission aboard an Orion spacecraft with an unmodified heat shield, critics assailed the space agency, saying it had made the wrong decision.

“Expediency won over safety and good materials science and engineering. Sad day for NASA,” Ed Pope, an expert in advanced materials and heat shields, wrote on LinkedIn.

There is a lot riding on NASA’s decision, as the Artemis II mission involves four astronauts and the space agency’s first crewed mission into deep space in more than 50 years.

A former NASA astronaut, Charles Camarda, also expressed his frustrations on LinkedIn, saying the space agency and its leadership team should be “ashamed.” In an interview on Friday, Camarda, an aerospace engineer who spent two decades working on thermal protection for the space shuttle and hypersonic vehicles, said NASA is relying on flawed probabilistic risk assessments and Monte Carlo simulations to determine the safety of Orion’s existing heat shield.

“I worked at NASA for 45 years,” Camarda said. “I love NASA. I do not love the way NASA has become. I do not like that we have lost our research culture.”

NASA makes a decision

Pope, Camarada, and others—an official expected to help set space policy for the Trump administration told Ars on background, “It’s difficult to trust any of their findings”—note that NASA has spent two years assessing the char damage incurred by the Orion spacecraft during its first lunar flight in late 2022, with almost no transparency. Initially, agency officials downplayed the severity of the issue, and the full scope of the problem was not revealed until a report this May by NASA’s inspector general, which included photos of a heavily pock-marked heat shield.

This year, from April to August, NASA convened an independent review team (IRT) to assess its internal findings about the root cause of the charring on the Orion heat shield and determine whether its plan to proceed without modifications to the heat shield was the correct one. However, though this review team wrapped up its work in August and began briefing NASA officials in September, the space agency kept mostly silent about the problem until a news conference on Thursday.

The inspector general’s report on May 1 included new images of Orion’s heat shield.

Credit: NASA Inspector General

The inspector general’s report on May 1 included new images of Orion’s heat shield. Credit: NASA Inspector General

“Based on the data, we have decided—NASA unanimously and our decision-makers—to move forward with the current Artemis II Orion capsule and heat shield, with a modified entry trajectory,” Bill Nelson, NASA’s administrator, said Thursday. The heat shield investigation and other issues with the Orion spacecraft will now delay the Artemis II launch until April 2026, a slip of seven months from the previous launch date in September 2025.

Notably the chair of the IRT, a former NASA flight director named Paul Hill, was not present at Thursday’s news conference. Nor did the space agency release the IRT’s report on its recommendations to NASA.

In an interview, Camarda said he knew two people on the IRT who dissented from its conclusions that NASA’s plan to fly the Orion heat shield, without modifications to address the charring problem, was acceptable. He also criticized the agency for not publicly releasing the independent report. “NASA did not post the results of the IRT,” he said. “Why wouldn’t they post the results of what the IRT said? If this isn’t raising red flags out there, I don’t know what will.”

The view from the IRT

Ars took these concerns to NASA on Friday, and the agency responded by offering an interview with Paul Hill, the review team’s chair. He strongly denied there were any dissenting views.

“Every one of our conclusions, every one of our recommendations, was unanimously agreed to by our team,” Hill said. “We went through a lot of effort, arguing sentence by sentence, to make sure the entire team agreed. To get there we definitely had some robust and energetic discussions.”

Hill did acknowledge that, at the outset of the review team’s discussions, two people were opposed to NASA’s plan to fly the heat shield as is. “There was, early on, definitely a difference of opinion with a couple of people who felt strongly that Orion’s heat shield was not good enough to fly as built,” he said.

However, Hill said the IRT was won over by the depth of NASA’s testing and the openness of agency engineers who worked with them. He singled out Luis Saucedo, a NASA engineer at NASA’s Johnson Space Center who led the agency’s internal char loss investigation.

“The work that was done by NASA, it was nothing short of eye-watering, it was incredible,” Hill said.

At the base of Orion, which has a titanium shell, there are 186 blocks of a material called Avcoat individually attached to provide a protective layer that allows the spacecraft to survive the heating of atmospheric reentry. Returning from the Moon, Orion encounters temperatures of up to 5,000° Fahrenheit (2,760° Celsius). A char layer that builds up on the outer skin of the Avcoat material is supposed to ablate, or erode, in a predictable manner during reentry. Instead, during Artemis I, fragments fell off the heat shield and left cavities in the Avcoat material.

Work by Saucedo and others, including substantial testing in ground facilities, wind tunnels, and high-temperature arc jet chambers, allowed engineers to find the root cause of gases getting trapped in the heat shield and leading to cracking. Hill said his team was convinced that NASA successfully recreated the conditions observed during reentry and were able to replicate during testing the Avcoat cracking that occurred during Artemis I.

When he worked at the agency, Hill played a leading role during the investigation into the cause of the loss of space shuttle Columbia, in 2003. He said he could understand if NASA officials “circled the wagons” in response to the IRT’s work, but he said the agency could not have been more forthcoming. Every time the review team wanted more data or information, it was made available. Eventually, this made the entire IRT comfortable with NASA’s findings.

Publicly, NASA could have been more transparent

The stickiest point during the review team’s discussions involved the permeability of the heat shield. Counter-intuitively, the heat shield was not permeable enough during Artemis I. This led to gas buildup, higher pressures, and the cracking ultimately observed. The IRT was concerned because, as designed, the heat shield for Artemis II is actually more impermeable than the Artemis I vehicle.

Why is this? It has to do with the ultrasound testing that verifies the strength of the bond between the Avcoat blocks and the titanium skin of Orion. With a more permeable heat shield, it was difficult to complete this testing with the Artemis I vehicle. So the shield for Artemis II was made more impermeable to accommodate ultrasound testing. “That was a technical mistake, and when they made that decision they did not understand the ramifications,” Hill said.

However, Hill said NASA’s data convinced the IRT that modifying the entry profile for Artemis II, to minimize the duration of passage through the atmosphere, would offset the impermeability of the heat shield.

Hill said he did not have the authority to release the IRT report, but he did agree that the space agency has not been forthcoming with public information about their analyses before this week.

“This is a complex story to tell, and if you want everybody to come along with you, you’ve got to keep them informed,” he said of NASA. “I think they unintentionally did themselves a disservice by holding their cards too close.”

Photo of Eric Berger

Eric Berger is the senior space editor at Ars Technica, covering everything from astronomy to private space to NASA policy, and author of two books: Liftoff, about the rise of SpaceX; and Reentry, on the development of the Falcon 9 rocket and Dragon. A certified meteorologist, Eric lives in Houston.

After critics decry Orion heat shield decision, NASA reviewer says agency is correct Read More »

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NASA is stacking the Artemis II rocket, implying a simple heat shield fix

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A good sign

The readiness of the Orion crew capsule, where the four Artemis II astronauts will live during their voyage around the Moon, is driving NASA’s schedule for the mission. Officially, Artemis II is projected to launch in September of next year, but there’s little chance of meeting that schedule.

At the beginning of this year, NASA officials ruled out any opportunity to launch Artemis II in 2024 due to several technical issues with the Orion spacecraft. Several of these issues are now resolved, but NASA has not released any meaningful updates on the most significant problem.

This problem involves the Orion spacecraft’s heat shield. During atmospheric reentry at the end of the uncrewed Artemis I test flight in 2022, the Orion capsule’s heat shield eroded and cracked in unexpected ways, prompting investigations by NASA engineers and an independent panel.

NASA’s Orion heat shield inquiry ran for nearly two years. The investigation has wrapped up, two NASA officials said last month, but they declined to discuss any details of the root cause of the heat shield issue or the actions required to resolve the problem on Artemis II.

These corrective options ranged from doing nothing to changing the Orion spacecraft’s reentry angle to mitigate heating or physically modifying the Artemis II heat shield. In the latter scenario, NASA would have to disassemble the Orion spacecraft, which is already put together and is undergoing environmental testing at Kennedy Space Center. This would likely delay the Artemis II launch by a couple of years.

In August, NASA’s top human exploration official told Ars that the agency would hold off on stacking the SLS rocket until engineers had a good handle on the heat shield problem. There are limits to how long the solid rocket boosters can remain stacked vertically. The joints connecting each segment of the rocket motors are certified for one year. This clock doesn’t actually start ticking until NASA stacks the next booster segments on top of the lowermost segments.

However, NASA waived this rule on Artemis I when the boosters were stacked nearly two years before the successful launch.

A NASA spokesperson told Ars on Wednesday that the agency had nothing new to share on the Orion heat shield or what changes, if any, are required for the Artemis II mission. This information should be released before the end of the year, she said. At the same time, NASA could announce a new target launch date for Artemis II at the end of 2025, or more likely in 2026.

But because NASA gave the “go” for SLS stacking now, it seems safe to rule out any major hardware changes on the Orion heat shield for Artemis II.

NASA is stacking the Artemis II rocket, implying a simple heat shield fix Read More »

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It’s increasingly unlikely that humans will fly around the Moon next year

artemis II, ground systems, orion, Science, Space / /

Don’t book your tickets for the launch of NASA’s Artemis II mission next year just yet.

We have had reason to doubt the official September 2025 launch date for the mission, the first crewed flight into deep space in more than five decades, for a while now. This is principally because NASA is continuing to mull the implications of damage to the Orion spacecraft’s heat shield from the Artemis I mission nearly two years ago.

However, it turns out that there are now other problems with holding to this date as well.

No schedule margin

A new report from the US Government Accountability Office found that NASA’s Exploration Ground Systems program—this is, essentially, the office at Kennedy Space Center in Florida responsible for building ground infrastructure to support the Space Launch System rocket and Orion—is in danger of missing its schedule for Artemis II.

During this flight a crew of four astronauts, commanded by NASA’s Reid Wiseman, will launch inside Orion on a 10-day mission out to the Moon and back. The spacecraft will follow a free-return trajectory, which is important, because if there is a significant problem with Orion spacecraft’s propulsion system, the trajectory of the vehicle will still carry it back to Earth. At their closest approach, the crew will come within about 6,500 miles (10,400 km) of the surface of the far side of the Moon.

The new report, published Thursday, finds that the Exploration Ground Systems program had several months of schedule margin in its work toward a September 2025 launch date at the beginning of the year. But now, the program has allocated all of that margin to technical issues experienced during work on the rocket’s mobile launcher and pad testing.

“Earlier in 2024, the program was reserving that time for technical issues that may arise during testing of the integrated SLS and Orion vehicle or if weather interferes with planned activities, among other things,” the report states. “Officials said it is likely that issues will arise because this is the first time testing many of these systems. Given the lack of margin, if further issues arise during testing or integration, there will likely be delays to the September 2025 Artemis II launch date.”

It’s increasingly unlikely that humans will fly around the Moon next year Read More »

nasa-confirms-“independent-review”-of-orion-heat-shield-issue

NASA confirms “independent review” of Orion heat shield issue

artemis, artemis I, artemis II, human spaceflight, NASA, orion, Science, Space, victor glover / /
The Orion spacecraft after splashdown in the Pacific Ocean at the end of the Artemis I mission.

Enlarge / The Orion spacecraft after splashdown in the Pacific Ocean at the end of the Artemis I mission.

NASA has asked a panel of outside experts to review the agency’s investigation into the unexpected loss of material from the heat shield of the Orion spacecraft on a test flight in 2022.

Chunks of charred material cracked and chipped away from Orion’s heat shield during reentry at the end of the 25-day unpiloted Artemis I mission in December 2022. Engineers inspecting the capsule after the flight found more than 100 locations where the stresses of reentry stripped away pieces of the heat shield as temperatures built up to 5,000° Fahrenheit.

This was the most significant discovery on the Artemis I, an unpiloted test flight that took the Orion capsule around the Moon for the first time. The next mission in NASA’s Artemis program, Artemis II, is scheduled for launch late next year on a test flight to send four astronauts around the far side of the Moon.

Another set of eyes

The heat shield, made of a material called Avcoat, is attached to the base of the Orion spacecraft in 186 blocks. Avcoat is designed to ablate, or erode, in a controlled manner during reentry. Instead, fragments fell off the heat shield that left cavities resembling potholes.

Investigators are still looking for the root cause of the heat shield problem. Since the Artemis I mission, engineers conducted sub-scale tests of the Orion heat shield in wind tunnels and high-temperature arcjet facilities. NASA has recreated the phenomenon observed on Artemis I in these ground tests, according to Rachel Kraft, an agency spokesperson.

“The team is currently synthesizing results from a variety of tests and analyses that inform the leading theory for what caused the issues,” said Rachel Kraft, a NASA spokesperson.

Last week, nearly a year and a half after the Artemis I flight, the public got its first look at the condition of the Orion heat shield with post-flight photos released in a report from NASA’s inspector general. Cameras aboard the Orion capsule also recorded pieces of the heat shield breaking off the spacecraft during reentry.

NASA’s inspector general said the char loss issue “creates a risk that the heat shield may not sufficiently protect the capsule’s systems and crew from the extreme heat of reentry on future missions.”

“Those pictures, we’ve seen them since they were taken, but more importantly… we saw it,” said Victor Glover, pilot of the Artemis II mission, in a recent interview with Ars. “More than any picture or report, I’ve seen that heat shield, and that really set the bit for how interested I was in the details.”

NASA confirms “independent review” of Orion heat shield issue Read More »

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Rocket Report: Astroscale chases down dead rocket; Ariane 6 on the pad

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RIP B1060 —

Rocket Factory Augsburg, a German launch startup, nears a test-firing of its booster.

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This image captured by Astroscale's ADRAS-J satellite shows the discarded upper stage from a Japanese H-IIA rocket.

Enlarge / This image captured by Astroscale’s ADRAS-J satellite shows the discarded upper stage from a Japanese H-IIA rocket.

Welcome to Edition 6.42 of the Rocket Report! Several major missions are set for launch in the next few months. These include the first crew flight on Boeing’s Starliner spacecraft, set for liftoff on May 6, and the next test flight of SpaceX’s Starship rocket, which could happen before the end of May. Perhaps as soon as early summer, SpaceX could launch the Polaris Dawn mission with four private astronauts, who will perform the first fully commercial spacewalk in orbit. In June or July, Europe’s new Ariane 6 rocket is slated to launch for the first time. Rest assured, Ars will have it all covered.

As always, we welcome reader submissions, and if you don’t want to miss an issue, please subscribe using the box below (the form will not appear on AMP-enabled versions of the site). Each report will include information on small-, medium-, and heavy-lift rockets as well as a quick look ahead at the next three launches on the calendar.

German rocket arrives at Scottish spaceport. Rocket Factory Augsburg has delivered a booster for its privately developed RFA One rocket to SaxaVord Spaceport in Scotland, the company announced on X. The first stage for the RFA One rocket was installed on its launch pad at SaxaVord to undergo preparations for a static fire test. The booster arrived at the Scottish launch site with five of its kerosene-fueled Helix engines. The remaining four Helix engines, for a total of nine, will be fitted to the RFA One booster at SaxaVord, the company said.

Aiming to fly this year… RFA hopes to launch its first orbital-class rocket by the end of 2024. The UK’s Civil Aviation Authority last month granted a range license to SaxaVord Spaceport to allow the spaceport operator to control the sea and airspace during a launch. RFA is primarily privately funded but has won financial support from the European Space Agency, the UK Space Agency, and the German space agency, known as DLR. The RFA One rocket will have three stages, stand nearly 100 feet (30 meters) tall, and can carry nearly 2,900 pounds (1,300 kilograms) of payload into a polar Sun-synchronous orbit.

Arianespace wins ESA launch contract. The European Space Agency has awarded Arianespace a contract to launch a joint European-Chinese space science satellite in late 2025, European Spaceflight reports. The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a 4,850-pound (2,200-kilogram) spacecraft that will study Earth’s magnetic environment on a global scale. The aim of the mission is to build a more complete understanding of the Sun-Earth connection. On Tuesday, ESA officially signed a contract for Arianespace to launch SMILE aboard a Vega C rocket, which is built by the Italian rocket-maker Avio.

But it may not keep it … In late 2023, ESA member states agreed to allow Avio to market and manage the launch of Vega C flights independent of Arianespace. When the deal was initially struck, 17 flights were contracted through Arianespace to be launched aboard Vega vehicles. While these missions are still managed by Arianespace, Avio is working with the launch provider to strike a deal that would allow the Italian rocket builder to assume the management of all Vega flights. The Vega C rocket has been grounded since a launch failure in 2022 forced Avio to redesign the nozzle of the rocket’s solid-fueled second-stage motor. Vega C is scheduled to return to flight before the end of 2024. (submitted by Ken the Bin)

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Update on ABL’s second launch. ABL Space Systems expected to launch its second light-class RS1 rocket earlier this year, but the company encountered an anomaly during ground testing at the launch site in Alaska, according to Aria Alamalhodaei of TechCrunch. Kevin Sagis, ABL’s chief engineer, said there is “no significant delay” in the launch of the second RS1 rocket, but the company has not announced a firm schedule. “During ground testing designed to screen the vehicle for flight, an issue presented that caused us to roll back to the hangar,” Sagis said, according to Alamalhodaei. “We have since resolved and dispositioned the issue. There was no loss of hardware and we have validated vehicle health back out on the pad. We are continuing with preparations for static fire and launch.”

Nearly 16 months without a launch … ABL’s first RS1 test flight in January 2023 ended seconds after liftoff with the premature shutdown of its liquid-fueled engines. The rocket crashed back onto its launch pad in Alaska. An investigation revealed a fire in the aft end of the RS1 booster burned through wiring harnesses, causing the rocket to lose power and shut off its engines. Engineers believe the rocket’s mobile launch mount was too small, placing the rocket too close to the ground when it ignited its engines. This caused the hot engine exhaust to recirculate under the rocket and led to a fire in the engine compartment as it took off.

Rocket Report: Astroscale chases down dead rocket; Ariane 6 on the pad Read More »

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NASA still doesn’t understand root cause of Orion heat shield issue

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Flight rationale —

“When we stitch it all together, we’ll either have flight rationale or we won’t.”

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NASA's Orion spacecraft descends toward the Pacific Ocean on December 11, 2021, at the end of the Artemis I mission.

Enlarge / NASA’s Orion spacecraft descends toward the Pacific Ocean on December 11, 2021, at the end of the Artemis I mission.

NASA

NASA officials declared the Artemis I mission successful in late 2021, and it’s hard to argue with that assessment. The Space Launch System rocket and Orion spacecraft performed nearly flawlessly on an unpiloted flight that took it around the Moon and back to Earth, setting the stage for the Artemis II, the program’s first crew mission.

But one of the things engineers saw on Artemis I that didn’t quite match expectations was an issue with the Orion spacecraft’s heat shield. As the capsule streaked back into Earth’s atmosphere at the end of the mission, the heat shield ablated, or burned off, in a different manner than predicted by computer models.

More of the charred material than expected came off the heat shield during the Artemis I reentry, and the way it came off was somewhat uneven, NASA officials said. Orion’s heat shield is made of a material called Avcoat, which is designed to burn off as the spacecraft plunges into the atmosphere at 25,000 mph (40,000 km per hour). Coming back from the Moon, Orion encountered temperatures up to 5,000° Fahrenheit (2,760° Celsius), hotter than a spacecraft sees when it reenters the atmosphere from low-Earth orbit.

Despite heat shield issue, the Orion spacecraft safely splashed down in the Pacific Ocean. Engineers discovered the uneven charring during post-flight inspections.

No answers yet

Amit Kshatriya, who oversees development for the Artemis missions in NASA’s exploration division, said Friday that the agency is still looking for the root cause of the heat shield issue. Managers want to be sure they understand the cause before proceeding with Artemis II, which will send astronauts Reid Wiseman, Victor Glover, Christina Koch, and Jeremy Hansen on a 10-day flight around the far side of the Moon.

This will be the first time humans fly near the Moon since the last Apollo mission in 1972. In January, NASA announced a delay in the launch of Artemis II from late 2024 until September 2025, largely due to the unresolved investigation into the heat shield issue.

“We are still in the middle of our investigation on the performance of the heat shield from Artemis I,” Kshatriya said Friday in a meeting with a committee of the NASA Advisory Council.

Engineers have performed sub-scale heat shield tests in wind tunnels and arc jet facilities to better understand what led to the uneven charring on Artemis I. “We’re getting close to the final answer in terms of that cause,” Kshatriya said.

NASA officials previously said it is unlikely they will need to make changes to the heat shield already installed on the Orion spacecraft for Artemis II, but haven’t ruled it out. A redesign or modifications to the Orion heat shield on Artemis II would probably delay the mission by at least a year.

Instead, engineers are analyzing all of the possible trajectories the Orion spacecraft could fly when it reenters the atmosphere at the end of the Artemis II mission. On Artemis I, Orion flew a skip reentry profile, where it dipped into the atmosphere, skipped back into space, and then made a final descent into the atmosphere, sort of like a rock skipping across a pond. This profile allows Orion to make more precise splashdowns near recovery teams in the Pacific Ocean and reduces g-forces on the spacecraft and the crew riding inside. It also splits up the heat load on the spacecraft into two phases.

The Apollo missions flew a direct reentry profile. There is also a reentry mode available called a ballistic entry, in which the spacecraft would fly through the atmosphere unguided.

Ground teams at NASA's Kennedy Space Center in Florida moved the Orion spacecraft for the Artemis II mission into an altitude chamber earlier this month.

Enlarge / Ground teams at NASA’s Kennedy Space Center in Florida moved the Orion spacecraft for the Artemis II mission into an altitude chamber earlier this month.

The charred material began flying off the heat shield in the first phase of the skip reentry. Engineers are looking at how the skip reentry profile affected the performance of the Orion heat shield. NASA wants to understand how the Orion heat shield would perform during each of the possible reentry trajectories for Artemis II.

“What we have the analysis teams off doing is saying, ‘OK, independent of what the constraints are going to be, what can we tolerate?” Kshatriya said.

Once officials understand the cause of the heat shield charring, engineers will determine what kind of trajectory Artemis II needs to fly on reentry to minimize risk to the crew. Then, managers will look at building what NASA calls flight rationale. Essentially, this is a process of convincing themselves the spacecraft is safe to fly.

“When we stitch it all together, we’ll either have flight rationale or we won’t,” Kshatriya said.

Assuming NASA approves the flight rationale for Artemis II, there will be additional discussions about how to ensure Orion heat shields are safe to fly on downstream Artemis missions, which will have higher-speed reentry profiles as astronauts return from landings on the Moon.

In the meantime, preparations on the Orion spacecraft for Artemis II continue at NASA’s Kennedy Space Center. The crew and service modules for Artemis II were mated together earlier this year, and the entire Orion spacecraft is now inside a vacuum chamber for environmental testing.

NASA still doesn’t understand root cause of Orion heat shield issue Read More »