Comment by somenameforme | Hacker News Reader

Comment by somenameforme | Hacker News Reader

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Extended space spays doesn't really wreck people, it's just that your body adjusts to the new environment so your strength decrease, your bone density decreases, your orientation mechanisms shift to 6 degrees of freedom, and so on. Of course when you get back to Earth you're body again has to go through a readjustment phase because those previous adjustments are now unfit for the new environment, but it's nothing beyond that. It'd be interesting to see what an extremely long stay of like a decade+ would do, but that's a major ask of anybody not only in time commitment but also because it's basically asking whether or not the transition would be fatal, and the answer is unclear.

As for a spinning station, that's something NASA will probably never do. They're extremely risk averse and you're opening up an unknowable, but very large, number of new possible failure scenarios there - many of them likely catastrophic. If anything that's something of an argument for genuine private stations who may have different levels of risk tolerance. Or we can just wait for China, because they'll 100% do it and probably relatively soon.

The results from ISS are much more pessimistic than you say, suggesting some irreversible damage besides the reversible changes, but I am lazy now to search links to the research articles. The weakening of the skeletal muscles is not the worst, but the deterioration of the heart muscle.

However, the research done on mice on ISS suggests that the undesirable effects can be mitigated by creating an artificial gravity (i.e. rotation) lower than on Earth, e.g. of 2/3 of Earth's gravity.

The failure scenarios for rotating spacecraft need not be more severe than for non-rotating spacecraft. For instance if 2 or more spacecraft, which can be also used independently, are connected with cables to enable them to rotate around the common center of mass, if everything is designed carefully the failure of the coupling system should not have any other consequences than the loss of the artificial gravity and from then on the failure risks would be the same as for non-rotating spacecraft.

As stated elsewhere, there's a very recent study [1] on astronaut heart health that's quite relevant. They studied the cardiovascular health of astronauts for 5 years after their return from long-duration stays on the ISS. They were all perfectly healthy.

For one obvious problem with rotation systems, stations need to be regularly boosted. You'll also need to occasionally reboost the local rotation. This sort of basic stuff is already fairly complex with a static station, and becomes exponentially more so with a local rotation going on. Even moreso because you want to be relatively fault tolerant in case of a partial or failed boost. Then you need to compensate for impacts, docking and undocking, and much more.

It's viable and almost certainly a solvable, but NASA is not the appropriate organization to do so. Their risk aversion makes it unlikely that they'll ever be doing much of anything revolutionary where failure could be catastrophic. They're having a tough enough time just trying to recreate what we already did 50+ years ago.

[1] - https://journals.physiology.org/doi/full/10.1152/japplphysio...

It's not just adjustment, there's a decent amount of evidence it's just bad for your health in general, apart from the issues when coming back to earth. Stuff like your circulation also gets messed up.

I'm active in this topic and have never heard anything similar to what you've mentioned. And in looking this up, there's a very recent study [1] that's quite relevant. They studied the cardiovascular health of astronauts for 5 years after their return from long-duration stays on the ISS. They were all perfectly healthy.

[1] - https://journals.physiology.org/doi/full/10.1152/japplphysio...

To expand on that - there are many body systems that depend almost entirely on the 1g glodilocks zone. Lymphatic systems movt , venous blood returning deox blood to the heart and even some digestive processes. Keenly dependent on a g value that allows proper muscle tone/function to the systems at play. Too little or too much and and human life becomes non-viable. Throw in the effect of ping ponging between microgravity and 1g and the issues multiply.

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