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Space anemia (arstechnica.com)
65 points by feross 7 days ago | hide | past | favorite | 43 comments

Definitely makes you wonder how dependent the human body is to gravity.

Would be interesting to run these tests on different groups experiencing varying degrees of gravity, on a spinning station perhaps, and see what's the minimum amount of gravity we can get away with while keeping side-effects to a minimum.

Long term tests would also be very valuable, 1-2 years.

Scott Kelly spent a year on the ISS while his twin brother Mark stayed on the ground for comparison studies.



I really feel like it's high time we try a rotating wheel space station to see if the artificial gravity fixes problems people develop in zero gravity.

My impression is that a rotating wheel space station, while theoretically well within the grasp of current engineering ability, would be extremely expensive given that we've never done it before.

These guys are planning to fly a prototype in 2023. https://orbitalassembly.com/

That's awesome! At least the prototype part for an automated truss build that they have the engineering for. The subsequent project timelines seem pretty fanciful, like we've built a truss then "hey presto", Pioneer station appears. That then made me question the initial prototype (which is q4 2023 so really 2024/2025). Have you been following this group for a while?

You wouldn't need an entire wheel, just two equally weighted compartments spinning about a centre point. In theory that's far cheaper. Perhaps you would purposely pump fluid back and fourth to maintain the correct centre of mass.

You could imagine a system where you 'space elevator' objects and people via the connecting cabling, whilst pumping fluid to offset the mass. You would likely want each side to be manned by two people.

You could later add more modules if designed correctly too. They would likely approach and attach to the centre (in a pair, one either sude), match the spin and then slot into their respective 'slots' and rotate on an arm.

It is prohibitively expensive until SpaceX's Starship brings launch costs down further.

It depends on what level of gravity is needed. The mass scales dramatically with acceleration.

And that it's big and heavy.

IIRC a spinning space station would only be beneficial if it was very large and thus far from Earth and expensive.

Otherwise the difference in gravity acting on different sides of the body and more importantly the Coriolis forces would wreak havoc and cause more harm than good.

There may be processes that use gravity to either sort proteins or concentrate chemicals. I can't think of much else, besides hormone response to stress caused by gravity.

From what I remember, the lymphatic system is basically open-ended. Blood vessels "leak" interstitial fluid, which flows through the body, collects into lymph vessels, and gets "pumped" by various processes back to the circulatory system.

Everything in chemistry is equilibrium-driven, so I can readily see some process evolving with the assumption of X units of some chemical flowing through this system, and trying to restore homeostasis in space by increasing hemolysis.

Ah, good point. That is most obvious. Blood pressure is unrqual and too high in the head in 0g, too low in the bottom extremeties.

I was imagining intracellular processes being effected. There are such processes in plants that are usually used for steering. In animals cells, if such thing exists, it may be minor efficiency changes in processes that add up to diverging from homeostasis.

Gravity is probably the big one as it is the hardest to approximate in space, but we're likely dependent on a lot of stuff that exists on Earth. We evolved to live on Earth. Earth may not be particularly suited for life, but what we consider life may be particularly suited for Earth.

Things like this amuse me in a way. I'm sure many of us have written code that worked a certain way based on assumptions we didn't realize we were making, or didn't realize could ever be incorrect. Why wouldn't we have evolved with similar "assumptions" based on terrestrial conditions?

And I don't think this is a novel observation on my part, but it does make me feel better when I have to refactor code when my assumptions turn out to be wrong.

Blood ultimately comes from your bones. Microtubule stress is known to be important to the hematopoietic process. The microtuble-binding drug plinabulin, for example, binds in such a way that helps ameliorate neutropenia. I would guess that these problems would be solved by artificial gravity. Another factor might be increased levels of background radiation, but I would guess that is already accounted for.

Have we run any centrifugal habitat experiments in space on animals to compare? The ISS is just a floating bunch of tubes.

If/when Starship becomes viable, a real space station becomes a real possibility.

As I read once, solar / cosmic ray radiation shielding isn't about thick lead armor, instead an envelope/shield of air/water vapor that is a 100m thick works better. Is that still the thought on practical radiation shielding in space?

Aren't blood cells made in our bones? If yes, it seems reasonable to assume that anything which affects bone density would also affect blood cell production, no?

The post contends that there's an increase in destruction and not a decrease in production.

Kinda puts 9 months needed to get to Mars into an interesting perspective.

Is there a "fast fix" for treating anemia? Because if humans do get there and land on a surface, this will probably be required.

Anemia is just one of a myriad of problems humans would face on a Mars trip. My chief concern, and the one that's probably hardest to tease out, would be the psychological stress. There's no escape pod, no truncated emergency schedule, no one to greet you on the other end, and potentially not enough work to keep you busy. These conditions are hard if not impossible to replicate on earth.

> These conditions are hard if not impossible to replicate on earth

Really? Where have you been for the last two years?

On the other hand, it does fully supports your hypothesis that the psychological stress will be huge.

Even at the height of Covid, I was still bundling up in PPE and going to the grocery store. Not to mention all the outside things to do.

Even the biosphere-style experiments, there's always the subconscious knowledge that you can make a call and bail at any time.

That's very different than knowing you have no lifeline. Les Stroud from Survivorman talks about how on one of his stints, he tested the emergency walkie/satellite phone or whatever and got nothing. So he's got some idea.

There are people out there who can do it, but it takes a special breed.

So yeah, take Covid stress, and like turn it up to 11.

It seems like death row inmates would be a good comparison group.

The majority of people who had prepared for the 2020 snap study elected to drop out after only a few weeks. Science, and humanity as a whole, are worse off as a result.

It’s not a problem at all. Some people are predisposed to turning psychological stress into a psychiatric pathology but there is nothing intrinsic about stress or space travel that causes psychiatric problems.

People on death row meet your criteria and probably endure more stress and a lot of them don’t develop psychiatric disease.

If stress is such a problem, then why not just sedate the passenger? Some forms of sedation can be quickly reversed as a last-ditch effort if there's a problem that the computer/mission control absolutely cannot solve.

Astronauts on the space station work out nearly every day for several hours to stave off atrophy and still have issues. Leaving someone sedated for months in a zero G environment would make the atrophy far worse.

> Kinda puts 9 months needed to get to Mars into an interesting perspective.

It doesn't take 9 months to go to Mars. It's true that the idealized Hohmann trajectory to Mars takes ~8.6 months, but reality is both a lot more messy and more amenable to optimization.

Just to take this year's launch window as an example:

The absolute lowest launch Δv trajectory is about 390 days, at 3.73km/s. This is obviously unworkable.

However, if you limit yourself to the lower, faster half of the porkchop plot, you'll find that the lowest Δv trajectory is ~200 days, at 4.3km/s.

If you are willing to spend 5km/s, you can bring the trip time down to ~150 days.

And if you have a fully retanked starship in orbit (assumptions: 250t mass at burnout including payload and landing fuel, 1200t tanks, 365s average Isp. These are very conservative, and will probably all be improved upon before any trip to mars is realistic.), which nets you 5615m/s, you can push that down to 130 days.

Anemia isn't a disease in and of itself, it's a symptom of something else. You don't treat anemia, you treat what's causing the anemia.

From reading the article, we don't know why it's happening. So we don't know how to treat it yet.

EPO is a medication that increases the number of red blood cells.

probably the EM field of the earth causes the blood to polarise in the correct way for iron to work properly

Not a doctor but perhaps we can give astronauts some sort of coagulants.

Eventually people will come to realize that humans don't belong in space.

Eventually people will come to realise that humans don't belong above 36°N.

If we don't get a handle on climate change, that statement will be that humans don't belong below 36°N (and 36°S)...

That too, which is why we need to get crypto-mining off-planet, stat!

We are completely off the rails on climate already. Best we can do is mitigate the full extent of the damage but our politicians can't quite pull it together.

And I'm over here wondering why we don't just migrate with the seasons.

We literally don't but the alternative is dying out here in this planet which is guaranteed to suffer some catastrophe eventually.

The most controversial opinion of all.

It’s a science and engineering problem.

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