[HN Gopher] Microgravity-induced muscle atrophy: Implications fo...
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Microgravity-induced muscle atrophy: Implications for long-duration
spaceflights
Author : KasianFranks
Score : 38 points
Date : 2023-10-11 02:19 UTC (13 hours ago)
(HTM) web link (journals.physiology.org)
(TXT) w3m dump (journals.physiology.org)
| Brometheus wrote:
| Don't live in microgravity.
| amelius wrote:
| Here's my design for solving this problem.
|
| Instead of sending one rocket, you send two. You link them with
| steel cables. Then you rotate them around to generate the
| required gravity.
| stoneman24 wrote:
| Yep, see Netflix film Stowaway for example. Once we get Spacex
| Starship working, fit 2 of them with Hab modules in the nose.
| Launch them and connect together at the nose and spin at
| different rates for moon gravity (G/6) and Mars gravity G/3).
| Use steel cables to increase radius and reduce required spin
| rate.
|
| A relatively cheap (for space) setup to get some good actual
| measurements.
| uoaei wrote:
| The whole "space is big" thing applies here, you can keep
| those two bodies super far apart. I don't really see a good
| reason for that tbh but it's possible. Though if the mission
| depends on those two bodies traveling together, you better
| have tons of redundancy or some propulsion systems to recover
| in case the cable snaps.
| stoneman24 wrote:
| Was really thinking of an earth orbiting laboratory setup
| with a radius of about 250m and rotation speeds of about
| 2-3 rpm. Need to model it when I have some time. Just to
| gain actual data on different gravities and durations. The
| starship has plenty of room for the habs to run experiments
| on plants and people. Each one has propulsion in case of a
| cable failure. You're correct, the cable snapping would be
| big concern.
| bjelkeman-again wrote:
| > Artificial gravity is provided to the crew on the way out to
| Mars by tethering off the burnt out Ares upper stage and
| spinning up at 1 rpm.
|
| From
|
| Mars Direct: A Simple, Robust, and Cost Effective Architecture
| for the Space Exploration Initiative, by Robert Zubrin,
| February 1991
|
| DOI:10.2514/6.1991-329
| temptemptemp111 wrote:
| [dead]
| [deleted]
| suzzer99 wrote:
| This seems like a real problem for older astronauts who will
| never be able to gain that muscle back.
|
| Muscle mass is so vital for long term health. 70-year-olds
| confined to bed rest for just two weeks have been observed to
| lose significant muscle mass that they most likely will never get
| back.
|
| Obviously most astronauts are younger than 70. But they're also
| losing a lot more muscle mass and bone density.
| inglor_cz wrote:
| Progress in stem cell treatments might be able to treat that
| muscle mass loss. We are getting closer to regenerating tissues
| at will, although obviously the main effort is concentrated on
| the cardiovascular system and nerves.
| voldacar wrote:
| You could just give the 70 year olds testosterone replacement
| and they would gain it back and more, probably
| MilStdJunkie wrote:
| One of the saddest parts of the science fiction novel _Aurora_ is
| that natural born human populations will have serious problems
| permanently separated from the larger ecosystem they're evolved
| for.
|
| It's a valid hypothesis. Humanity would need to have an entire
| engineered biosphere to replace the biome living in our guts, our
| eyes, our . . everywhere. And anywhere we find that's close
| enough to Earth to live in, will have . . _something_ else . .
| almost certainly[1] already there.
|
| Kim Stanley Robinson isn't an easy read if you're on the other
| side of the political spectrum, but Aurora is comparatively free
| of his standard preachiness, at least in my ears. I actually
| disagree with his primary thesis of Aurora, and the novel suffers
| from some fundamental problems as a story, but the point is still
| salient. Humans will have to build their own Earth, wherever they
| end up, either out there or back here. I have a funny feeling we
| won't learn to treasure our own planet until we find out how much
| work it is to live on another.
|
| [1] Particularly given the extraordinarily early date of the
| first Terran lifeforms. It doesn't seem to take too much to get
| the ball rolling, unless the panspermia theories actually turn
| out to hold some water.
| pyinstallwoes wrote:
| They don't call it Spaceship Earth for nothing!
| diogenes4 wrote:
| > I have a funny feeling we won't learn to treasure our own
| planet until we find out how much work it is to live on
| another.
|
| Optimistic! I have a feeling we won't learn to treasure our own
| planet until we _fail_ to reach another. The problems here are
| simply too massive for us to coordinate spreading to other
| places.
| shiroiuma wrote:
| We'll learn to treasure our own planet when the ecosystem
| becomes uninhabitable for us and we start going extinct.
| kzrdude wrote:
| "Earth is our spaceship"
| shiroiuma wrote:
| >And anywhere we find that's close enough to Earth to live in,
| will have . . something else . . almost certainly[1] already
| there.
|
| *No* place is going to be "close enough" to Earth to live in:
| the closest star system is 4 light-years away, and will take
| tens of thousands of years to travel to with anything remotely
| like current technology. The only way we're going to find
| another planet "close enough to Earth to live in" is if we
| invent a real, working, practical FTL drive. That's not
| terribly likely. Well, there is one other possibility: some
| glowing blue alien substance called "protomolecule" is
| discovered in our solar system and somehow (through a long,
| twisting plot arc) takes over an asteroid with 100k people,
| assimilates their biological matter, crashes on Venus, then
| travels to the outer system and builds a Ring Gate. Anyway...
|
| Basically, we're stuck with this planet, the not-at-all-like-
| Earth worlds near it, and the other resources of this system.
|
| The only real way we're going to create a viable, Earth-like
| colony is to build an O'Neal Cylinder.
| MilStdJunkie wrote:
| Sibling is right, "close enough" == "habitable surface that
| humans can live on without some life support".
|
| Aurora uses the generation ship model of transport, which . .
| does not go _ideally_. Many problems unforeseen for hundreds
| of years of travel in the utter empty (you hope desperately
| that it is empty). It 's also a fast but not relativistic
| ship, .07C, at exorbitant energy costs. Hope you like the
| moon / mercury covered in purple lasers. Relativistic lower-
| mass vessels with the same technology, I guess, but the
| impact threat goes through the roof, and it's not a
| settlement ship. A better way to make the Aurora-style
| project is a small ship with frozen embryos that get birthed
| insitu by machines of loving grace. Then you can go faster,
| smaller.
|
| But it's all talk talk. We're technically capable of doing
| these things, but I'm not sure we're socially capable of even
| lunar settlement at this stage of our history. Let alone
| Mars, the outer system. The Expanse was, in its own way,
| optimistic about our future. They just had to get medieval to
| get Earth's gas balance (and probably phosphorous! and who
| knows what else) back in the normal range.
|
| Heh heh you know it's funny but if we took the solar system
| as it exists right now, a floating settlement higher up in
| the Venutian cloud layers would be closest[1] to fitting that
| bill, in terms of kgs of crap you need to carry around
| outside with you. Just, yknow, not anyone's typical idea of a
| "settlement".
|
| [1] And yet so very damn far away.
| jonathanlydall wrote:
| I read their "close enough" as in regards to similarity of
| climate/environment, not in regards physical distance of the
| other planet from Earth.
| chr1 wrote:
| > The only way we're going to find another planet "close
| enough to Earth to live in" is if we invent a real, working,
| practical FTL drive.
|
| That is not the only way, extending lifespan would work as
| well
| dmarchand90 wrote:
| I wonder if you could bypass these issues with strength training
| machines designed for space. E.g a squat machine that pushes down
| from above, cable tension based arm movements, etc. I bet if
| you're clever you can probably have a small room that can get the
| essential exercises in and takes up a similar amount of room as a
| toilet
| HPsquared wrote:
| The ISS has a space barbell:
|
| https://en.wikipedia.org/wiki/Advanced_Resistive_Exercise_De...
| dmarchand90 wrote:
| Now I'm curious how the results of study posted would be
| mitigated by the space barbell
| HPsquared wrote:
| I guess the problem remains that the legs still don't need
| to lift the body weight.
|
| For example in a barbell squat, your shoulders lift the
| bar, but your legs lift that weight plus your bodyweight.
| In space, bodyweight is not a factor so your legs only have
| the same load as the shoulders. So upper body / shoulder
| might end up being the limiting factor, not giving the legs
| the same amount of load they would under gravity.
| vmfunction wrote:
| You can always just train like some anime character or
| kung fu masters:
|
| https://www.youtube.com/watch?v=crKohKpVoAM
| freilanzer wrote:
| That could be solved via a vest that you wear, that has
| additional cables pulling with a force of the bodyweight.
| That way you could also do pull ups with your bodyweight.
| 3seashells wrote:
| Could Ems or sleeping in a spinning drum overcome this?
| inamberclad wrote:
| EMS = electro muscular stimulation? No, not 100%. Astronauts
| have very good resistance training onboard the ISS at this
| point. Some of them come back to earth stronger than they left.
| However, it turns out that your body also needs skeletal
| loading in order to produce strong bones. That kind of loading
| comes from having large forces distributed through the entire
| body. NASA tried a variety of shortcuts around resistance
| training, but none of them were satisfactory.
|
| A spinning drum is probably the best method short of artificial
| gravity, but it has a couple problems. A rotating reference
| frame creates some pretty non-intuitive effects
| (https://www.youtube.com/watch?v=bJ_seXo-Enc). Research is
| ongoing about just how fast a human can be spun for a long
| duration, although data is hard to come by. We also don't know
| how low of a gravity a human can stay healthy in without
| intervention like serious exercise. If it turns out that you
| need 1G, that involves a much larger spinning drum than a G/3
| (Mars) or G/6 (Moon) environment. The problem is that we really
| have no way to simulate those environments for a human.
| RetroTechie wrote:
| Given the travel time, any visit to Mars would probably not
| be short-stay like 1 day. More likely weeks, months or
| longer.
|
| So you'd have Mars G for time on the surface anyway.
|
| And besides: a few astronauts have already done long duration
| microgravity, returned to Earth & lived to tell.
| mealkh wrote:
| What about flywheel training? You can do deadlifts, squats
| etc with it that will produce large spinal/skeletal load even
| in the absence of planetary gravity due to the inertia.
| Something like https://exerflysport.com/ or
| https://exxentric.com/store/kbox/
| iampivot wrote:
| I wonder if it's really required to have 1g gravity in order to
| avoid this. It's much easier to artificially create, say 1/6g
| (moon) gravity by rotation than 1g, since rotational speed
| required is quite a bit slower.
| uoaei wrote:
| I wonder how much the rotation speed really matters. It comes
| down to the tensile strength of the material required to hold
| everything together I suppose but most metals should be able to
| handle 1g just fine. Once it's rotating you don't need much
| energy to keep it going, just enough to overcome any frictional
| losses from whatever interfaces happen to be required.
| iampivot wrote:
| There's also the issue of dizziness if rotating fast with a
| small radius.
| leoff wrote:
| Could one become stronger by living in 2g?
| heavenlyblue wrote:
| would that be similar to weari nb a backpack having weight
| same to your body?
| reportgunner wrote:
| Not too similar, imagine all the liquids in your body while
| running at 2g.
| stoneman24 wrote:
| To echo some of the points from the aurora book, I think that
| the human body is really well optimised for 1G environments.
| We know that there are issues in zero gravity. As you adapt
| to 2G, you may well get stronger but the stress and strains
| may have a severe effect on health, life expectancy. Hate to
| think about the effects on your blood pressure etc
|
| Your great grand kids might eventually cope.
| narag wrote:
| That's actually seen in anime. In Dragon Ball Z, Goku trained
| in 100 G. I remember thinking it was clever. It reminded me
| of Spain national football team training for some weeks in La
| Paz previous to Mexico World Cup in 1986. The idea is
| enduring harder conditions (> altitude -> less oxygen) to
| overcompensate.
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