18 thoughts on “The Orion Heat Shield”

  1. 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.

    Eh? How so? I thought Orion in all cases was returning from the Lunar Gateway? What difference does the Artemis docking of the Lunar Starship at the Gateway change the flight profile of the Orion?

    Won’t any potential higher speed re-entries all start with the first return from the Gateway at NRHO? Regardless of lunar landings?

    Editorial license at work?

  2. 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.

    Live by the computer model, die by the computer model. Sure computer models can be improved, but this would have been found long ago with a sensible development tempo which involved a lot of real world test flights.

  3. Launch it with a couple of observers – I suggest Ballast Bill (he’s astronaut trained) and a random NASA project manager from the JWST project…

    Let them see what happens

  4. Let me get this straight. NASA paid $4B to Boeing for an orbital space capsule and it’s NASA’s problem to figure out what went wrong with and to fix the heat shield?

    1. More like $10+ billion to Lockheed for Orion, and the thing still is in search of a reason to exist.

  5. And Orion/SLS stumbles forward…
    A most unimpressive program.
    That”s not intended as a slight to the engineers doing the work – they are doing their best within poorly considered constraints.

  6. One thing that caught my eye is that they’re doing a skip re-entry, noting that it’s different from the usual direct entries.

    That makes me wonder what happens right below the char layer. Is there internal vaporization and gas pressure? In a direct entry there would be a compression of the char layer from aerodynamic forces. But if they skip back out, the aerodynamic pressure is rapidly cut back to vacuum while the the outer surface of the heat shield is still extremely hot.

    If the aerodynamic re-entry pressure disappears, could any internal gas pressures below the char layer provide a force that causes part of the outer surface to flake off? I would think if internal gases can form, they’d be below the dynamic pressure on the skin, otherwise they’d sizzle out. But once formed, and while the skin is still extremely hot, maybe sticking the skin back into a vacuum causes problems.

    Just a thought.

    1. Scott manley did a commentary video where he voiced over this. Skip reentries are pretty cool.

  7. Here we see the difference between a timid mindset based on testing of exquisite artisanal objects that are too rare and expensive to really wring out properly and a mass production mindset in which the test articles are intended to be expendable and are cranked out cheaply and in quantity in what amounts to an oversized sheet metal shop.

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