Exploring Sealed Apollo Hardware with an Industrial Computed Tomography Scanner

Many of the electronic components in the Apollo spacecraft were “potted” in an epoxy-like material to protect their insides from vibration, moisture, and corrosion. In addition, other “black boxes” such as gyroscopes and the spacecraft’s master clock were packaged in magnesium cases which were welded shut and pressurised with dry nitrogen gas, which would allow them to operate regardless of the atmospheric pressure inside the spacecraft.

While this was fine for going to the Moon, it’s a real drag for technological archæologists seeking to bring this equipment back to life half a century after it was retired. Industrial computed tomography (CT), which uses X-rays taken at many different orientations around an object to reconstruct its three dimensional internal structure, can come to the rescue in many such situations, as long as nothing in the object is opaque to X-rays from all angles.

Fortunately, in the interest of saving mass, Apollo gear used a lot of light (“low-Z”) elements such as magnesium and beryllium, which a powerful X-ray can see through. Here, the intrepid Apollo restorers visit Lumafield, which volunteered time on one of their CT scanners to look inside four pieces of sealed Apollo hardware:

The results are stunning—one of the restoration team said, “It’s not magic; it’s witchcraft.” You can interactively explore these scans yourself with the Lumafield browser-based viewer, but you’ll have to create an account on their site to access the scans.

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Ken Shirriff’s articles on this topic are excellent.

There is no shortage of artifacts from the mid 1960s, especially the space program. It’s very interesting to think that absent documentation even simple modules like the flip flop circuit analyzed in this article would be esoteric pieces of engineering.

I enjoyed his article on the “talking with the moon” quite a bit.

Technology has advanced quite a bit in the intervening 50 years, yet we could no longer duplicate the trip to the moon feats of that period. Seems counter intuitive when you think of the apparent ease with which SpaceX, for instance, has redeveloped booster technology and crewed capsules, etc.

Is this driven by the bureaucratic requirements imposed by NASA? Something else altogether?

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In my opinion, it was indeed partly bureaucratic requirements, but not entirely. I think the real problem is it was arguably too early to go to the Moon for anything other than national security interests and robotic research. The materials technology was just barely able to do it, there are a host of health issues for long duration stays, moon dust is a real problem, it takes a lot of mass to deal with solar radiation, it required an army to manage the computation requirements, a larger army for the other support, hardware problems (eg. pogostick burning), etc. Some of these have been mitigated by later developments, but not all of them.

There were other issues, of course.

Politicians usually don’t like programs that are not going to pay off while they are still in office. The Cold War was on so private launch that wasn’t under the thumb of a responsible national government was treated with great suspicion (OTRAG was shutdown for valid Cold War reasons.) With minor exceptions, launch vehicles were refitted weapons platforms, which have a very different economic profile than commercial launch (total throw weight to target vs. $/pound to orbit.) See J. Walker’s 1993 A Rocket A Day for more economic discussion. No one saw clear economic benefits in excess of the national budget level expenses (Manhattan Project was 27 Billion in 2019 USD, Apollo was 150 Billion in 2019 USD ). If they had, someone might have tried hard enough to push on the bureaucracy. Solar Power Satellites were an attempt to define a reason to go (lunar mining for the second generation SPSs), but the inventors of that engaged in too much hand-waving and wishful thinking. The space station is some place to go for human spaceflight, but that doesn’t involve the Moon. (However it fits nicely into the NASA Manned Spaceflight Division unofficial motto:“Making Space Safe For 40 Year Old PhDs.”)

Now that there has been some progress in some of those areas, we have a number of private businesses trying to apply the advances. These businesses do indeed hit the bureaucracy, but they push back. And of course the bureaucracy needs Musk et.al. because their own programs usually fall over.

Edit: line break, add dropped ref

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Stumbled onto a good overview of the dust issue.

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This study is particularly interesting since it involved astronauts on space shuttle missions between 1998 and 2001, which were all in low Earth orbit and, prior to permanent habitation of the International Space Station, short duration. (It is possible some of these people may have visited the Mir space station for longer duration, but this is not mentioned in the article.)

In low Earth orbit, there is increased radiation compared to lower altitudes, but you’re still below the magnetosphere and shielded from most galactic cosmic rays and solar activity radiation by the Earth’s magnetic field. The radiation doses experienced by people in low Earth orbit are below those which have been shown to have effects on health in others exposed to low-level radiation.

So, one wonders whether the observed effects may be due to something else, for example, exposure to microgravity. We know this causes shedding of calcium from the bones, loss of muscle tone, a change in fluid distribution, and is suspected to contribute to the observed weakening of immune response in long-term space flight crew. Perhaps there may be other pernicious effects of an environment with which terrestrial life never co-evolved.

If this is the case, the priority for developing rotating habitat artificial gravity for long-term missions and research into the effects of long-term exposure to lunar and Martian gravity levels should be increased. There was a plan to include a 2.5 metre centrifuge on the International Space Station to study the effects of various gravity levels on biological specimens, but it was cancelled due to budget constraints and is rusting away outdoors in Japan today.

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Other possibilities: they aren’t breathing normal air at normal pressures, they’re in a lot of stress in the air and on the ground. It would be interesting to test astronauts that haven’t flown yet or Russian astronauts who never used American facilities.

I’d like to see a paper, the description doesn’t mention any control groups, just they want to do controlled studies with this a a jumping off point. I would laugh it if turned out it was asbestos or something in the facilities at Houston.

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Actually, they are. The International Space Station (ISS) and Shuttle both use a nitrogen/oxygen mixture at close to sea level atmospheric pressure. While earlier U.S. manned spacecraft used pure oxygen at around 5 psi and Skylab used a 74% oxygen 26% nitrogen mixture at 5 psi, problems experienced due to the low pressure and pure oxygen caused the Shuttle and later ISS to use a nitrogen/oxygen mix at sea level pressure (14.7 psi, 101.3 kPa). This turned out to be a lucky choice when the Russians joined the project, as their spacecraft and space stations have always used this mix and two different gas mixtures and pressures would have been a mess (as it was in the Apollo-Soyuz docking in 1975). The atmosphere isn’t identical to Earth’s—they don’t bother to include the around 1% of argon, for example, but it’s considered physiologically equivalent.

The high pressure and nitrogen content in the Shuttle and ISS complicate the the EVA process, as the space suits use pure oxygen at 4.5 psi. Before an EVA, astronauts on the ISS have to pre-breathe pure oxygen for four hours to purge the nitrogen from their bodies in order to prevent decompression sickness (“the bends”) at the lower pressure in the suit.

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OK. For some reason I had thought they were using the Skylab approach. Still doesn’t mean something isn’t missing we don’t know is important.

And I found the original paper:
https://www.nature.com/articles/s42003-022-03777-z
https://www.nature.com/articles/s42003-022-03777-z.pdf (PDF)

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