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Comment by idlewords | Hacker News Reader

The Apollo command module used Avcoat, the same material as Orion. But there are two key differences:

1. The application method is different. Apollo applied it to a metal honeycomb structure with very small cells, while Orion uses blocks of the material. (NASA tried the honeycomb approach for Orion, but it was too labor-intensive).

2. Orion is much bigger and heavier than the Apollo command module. The informal consensus is that Apollo may have been at the upper size limit for using Avcoat.

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> NASA tried the honeycomb approach for Orion, but it was too labor-intensive

So cost cutting, as always.

Engineering is done in the context of constraints, cost is one constraint - and its a relatively conserved constraint. Saving labor in one area allows for more care in other areas. Especially given that labor is often not cost constrained, but skill constrained, which is less elastic.

Apollo was ridiculously expensive. it was a proof of concept, but not sustainable for long term exploration

How expensive in comparison to the nuclear submarines or nuclear carriers?

At its peak the Apollo program was about 6% of US GDP.

About 4% of the federal budget and 6% of discretionary spending at its peak, not of GDP.

Still a very high number, but nowhere near the military-budget-levels you're talking about.

> How expensive in comparison to the nuclear submarines or nuclear carriers?

SLS already costs about as much as a nuclear submarine. Per launch.

The Apollo program cost about as much as 22 Gerald Ford class nuclear carriers.

Amortized over the whole program, each launch cost the same as building 2 Gerald Ford class nuclear carriers, or $26 billion USD.

You would be the first person to ever accuse the Orion program of cutting costs.

There's different kinds of costs: cost to the government, and cost to actually build the thing.

The contractor has no trouble inflating the first one whenever they can, but they want to strip the second one to the bone to maximize profits.

More precise would be:

NASA is an organization that is dysfunctional and way too expensive for what it does. It then decided to use agressive cost cutting to cover up these problems.

The fix for not doing that by hand is to get a robot to do it, given the applicator is human-held, a human-strength Kuka with enough reach to cover the area it can handle before the applicator needs refurbishment of some sort which would give a good opportunity to move the robot to a new section of the heat shield.

Labor intensive methods aren't automatically better: you have more manual steps which must be done perfectly and validated etc.

For the Apollo spacecrafts:

> The paste-like material was gunned into each of the 330,000 cells of the fiberglass honeycomb individually, a process taking about six months. [1]

[1] https://en.wikipedia.org/wiki/AVCOAT#Apollo_Command_Module

Thats what engineering is. If you dont have to consider cost or labor, a lot of engineering becomes much easier.

How reliable is this information?

Just out of curiosity, do we know if the honeycomb method worked before it was deemed too labor intensive? Because I'm told that using this block method results in chunks blowing out.

I'm also having a problem with this set-up: Apollo is at the upper size limit for avcoat; Orion is way bigger; use avcoat.

Reading a real front-fell-off aura from this project. It makes me wonder if spending 6% of GDP to develop and run a crewed lunar program 60 years ago and then immediately destroying the evidence, r&d artifacts, and materials fab capabilities was a good idea.

Apparently, it worked too well in Lockheed Martin opinion.

>Temperatures on re-entry “were lower than we expected” on EFT-1, Hawes told reporters here during Lockheed Martin’s annual media day.

>That data supports a Lockheed Martin proposal to scrap the current heat-shield design, which features a 5-meter-diameter honeycombed frame, in favor of an alternative composed of rectangular heat-resistant tiles glued together with a silicone-based adhesive, Hawes said.

https://spacenews.com/lockheed-martin-pressing-to-simplify-o...

too labor intensive - each launch already costs like $1bn, how bad can it be

As explained in the article, it’s typical margin cutting.

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