Earlier this year, NASA announced it was delaying the moon launch of crewed Artemis 2 until September 2025, a drill exercise in preparation for the 2026 Artemis 3 mission that will land astronauts near the moon’s south pole.
One reason for the 10-month delay was getting to the bottom of the reentry heat shield data. Artemis 1Which sent an uncrewed Orion capsule into lunar orbit and back.
Engineers are analyzing the data obtained from that shocking journey that started with NASA’s launch. Space Launch System Megarocket on November 16, 2022.
The 25-day Artemis 1 mission ended on December 11, 2022. Hunter Capsule splashing under parachutes in the Pacific Ocean off Baja California.
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surging re-entry
Orion’s heat shield expertly protected the capsule that day, reaching a reentry speed of 25,000 mph (40,000 km/h). But soon NASA and contractors began grappling with the discovery of Orion’s ablative heat shield. eroded differently than expected.
Some areas of the material expected to char were eroded in ways that could not be predicted by computer modeling and ground tests. Additionally, slightly more charred material than expected was released during reentry.
Orion’s heat shield contains the same corrosive material used during combat, called Avcoat. Apollo program In the late 1960s and early 1970s. However, the construction process of the heat shield was changed to the Apollo era method.
Vintage Apollo
While Avcoat is classic Apollo, the manufacturing process for Orion’s 21st century thermal protection system has been changed.
Leading company according to Lockheed Martin Orion’s heat shield The development process states that “instead of workers individually filling 300,000 honeycomb cells with abrasive material, then heat-curing and shaping the material into the proper shape, the team now produces pre-machined blocks of Avcoat (just under 200) to fit their positions and bond to the carbon fiber covering of the heat shield.” According to the aviation company’s statement website explains.
According to the company, this process allows Avcoat to be applied in just a quarter of the previous time and also saves money.
Root cause
Post-flight inspection of the Artemis 1 Orion heat shield revealed an unexpected loss of charcoal fragments from the spacecraft. NASA was literally laser-focused on understanding the root cause of the Avcoat cracking as well as the coal loss phenomenon.
“We designed and implemented a building-block ground test approach using agency and external test facilities,” NASA’s Orion program office told Space.com.
The first test series started in the summer of 2023 and was completed with the final test series in December 2023. “We expect to determine the root cause this spring,” the NASA office said.
Simulation test
Orion heat shield testing involved the Laser Hardened Materials Evaluation Laboratory, a unique facility operated by UES, a BlueHalo company, in Dayton, Ohio, and managed by the Air Force Research Laboratory. This laboratory performs thermal simulation tests equipped with high-power lasers.
Testing also took place at NASA’s Arc Jet Complex. Ames Research Center In California’s Silicon Valley. Arc spray testing is performed on thermal shielding material with plasma that mimics the intense heat generated during the Orion capsule’s re-entry into the atmosphere.
Blaine Brown of Orion Spacecraft Mechanical Systems said Lockheed Martin is working with NASA to assemble a core team of engineers to investigate and understand what caused the coal loss and what needs to be done to prevent similar events on future flights. Manager in the company.
“Over the past year, the Lockheed Martin team, along with NASA, has been very busy producing test articles and supporting reentry environmental testing in various NASA and industry test suites,” Brown told Space.com.
Those tests produced a wealth of information for the investigative team, Brown said. “Lockheed Martin also provides analytical expertise to demonstrate acceptable thermal margins to support flight logic. Artemis 2 mission.”
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Heat shield hiccups
Last year NASA’s Orion program office Johnson Space Center In Houston, a response was made to Space.com’s request for comment on heat shield hiccups.
“We expect the material to be corroded by 5,000 degrees Fahrenheit [2,760 degrees Celsius] spacecraft encounters on reentry earth atmosphere“The NASA office saw that the material was charred through a chemical reaction, but we did not expect small fragments to emerge from the cut-out site,” he said.
The program office statement noted that a healthy margin remained on virgin Avcoat and temperature data inside the cabin remained at expected levels, meaning the crew would not have been in danger had they been on board.
NASA said a special investigation includes planned testing, detailed analysis, extensive sampling of the heat shield and reviewing data from sensors to assess what the Orion capsule experienced during reentry.
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Is Avcoat changing?
Might changes need to be made to Avcoat?
The NASA office responded in its 2023 statement: “It is too early in our testing and analysis to reach any potential recommendations or solutions for additional coal deregulation.”
At the time, the office said that the Artemis 1 heat shield phenomenon may be unique to this heat shield.
Moreover, this may be what NASA expects when the capsule returns. moon“But we will let the data inform us,” the Orion project office said, adding: “Our teams want confidence that we have the best possible heat shield to fly humans in the future.”