hckrnws

It takes a few clicks to get to the supplemental data movie:

https://rs.figshare.com/articles/media/a_participant_running...

You'd probably want to switch directions often!

The ankle flex when the right foot lands makes me wince every single time. I wonder how much that's to do with the direction of gravity, the angle of their body looking not quite horizontal (and therefore 'weirding' the angle that feet hit the ground), and how much is to do with the individual's physiology.

You could build it with a slight angle. Or gradually steeper like a high speed race track.

The ‘bowls’/balls used for motorcycle stunt riding might be good examples for this (and could be fun).

In actual lunar gravity the forces should balance out. At a particular speed, tied to the wall angle, the forces should align with the floor to let the foot land as if running on a horizontal surface. Imaging a motorcycle in a turn. Then tilt the road to match the bike's lean angle. The tire/foot then falls flat against the road.

due to the angles, it would be like running in a circle on earth. It is mostly a question of what the equivalent earth track diameter is. It can be quite painful and damaging to run in small circles.

Why? The bungee cord is only needed for earth gravity.

Because the moon still has gravity, and there would be some asymmetrical force on your legs either which would be reversed if you went the other direction. So switch directions all the time to be less lopsided.

The runner will feel a pull to the left, as if the track had a slope in that direction. I wonder if that could give motion sickness to somebody. Probably people sent to the Moon will be selected against that because of the journey to and from the Moon but I really have no idea about that.

Another problem, as pointed out by someone else in the comments, is that the floor is not flat but points upward and the feet and ankles might feel that. Furthermore it's another possible source of motion sickess (flat but not flat.)

The moon has a sixth of earth gravity. The force you would feel would be very small and the whole point of this is to increase the resistance against the wall you’re running on.

If you’ve ever been on a spinning wheel at a carnival where they move the whole thing 90 degrees it would be a bit like that.

The track would actually be straight, so you wouldn’t have to compensate for turning even.

I’m not saying you wouldn’t want to switch directions, but there shouldn’t be some imperative to do so often.

It's not a symmetric exercise, look at the feet. You'd probably want to keep the overall workout balanced by alternating periodically?

I.e. “don’t skip the left day!”

It's because walls are a bit too steep. If you made them into paraboloid, a per would naturally climb as high as they need to, to be able to run symmetrically.

But one leg will still be running a shorter distance then the other.

Person running would need to constantly turn a bit to one side to not climb further up the wall. So it shouldn't be much different from running in circles on flat surface.

Not sure if runners that train by running in small circles are concerned about evenness and try to run the same amount clockwise and counter clockwise to even things out.

Ex collegiate track and XC athlete, yes, we'd alternate directions once in a while when doing long workouts on the track. It's a 36.5m radius, and it does get to you eventually. You feel it in your knees long before your ankles. I ran distance events (1500, 3200, 5k), so I think I had it easier than the 200m and 400m guys (and especially the 400m/300m hurdle guys) whose spikes were desperately clawing at the track to hold the turn, but I did have some workouts with a lot of laps. We didn't bother to make it exactly even, but if we were doing ladder workouts we'd switch directions somewhere near the middle.

Indoor meets often had 200m tracks with tighter (frequently nonstandard!) radii. The good ones were banked, though it never seemed to be at the right angle, always too steep or too shallow.

Every race still goes counterclockwise, though.

Maybe it's my XC side talking, but I'd love to see a track in a figure 8 with an underpass. Left turn, over the bridge, right turn , under the bridge, and repeat! It would break up those monotonous 8 and 12 lap races nicely, and you could fit a longer track in a shorter rectangular building by using the hypotenuse. I'm sure people would hate the hilly incline, though...

I did HS sprinting as cross training for fencing. Fencing is extremely asymmetric, to the point where my right (front) leg could lift twice the weight of my back (left) leg. It was freakish, and probably not healthy lol. It made my sprinting coach really uncomfortable, because my stride looked weird on the straights.

The curves felt great for me though, I really liked the 200m better than the 100m. Can't imagine how shitty it'd have been for a left handed fencer to run track, because the big muscles would be on the inside leg.

That would be extremely interesting, but the fact that you have an incline would change the ideal body type and tactics so much it would be a different sport at that point.

But I would love to see it for medium distances, just to see what crazy stuff would happen!

Yes for sure. Track running can result in injuries on the left side usually in the foot/ankle area.

This is steaming my brain a bit. Is it not the case (assuming an "optimal" tilt of the track) that the inner leg would travel more radii each step, meaning you would travel a larger segment of the circle on every inner step than outer step, ending up with an equal gait? This is my intuition without any formulated proof.

I didn't see any mention of having a spinning surface.

A tapered cylinder "gravity gym" with adjustable angled walls, and variable speed spinning, could smoothly create much greater "gravity".

Spin gravity would also enable body weight exercises, core exercises, stationary or small area cardio like exercise bikes, VR games, yoga, etc. Even sleeping.

EDIT: I missed this:

> but Moon-based centrifuges allowing locomotion inside would pose technical challenges

Still think it will be inevitable. Far more useful physically and psychologically. "Spinning surface" is a simple challenge, compared to "low-g health deterioration" and "bored to death of running in circles".

Equipment like this might resolve issues with off-world childbearing. Time to "spin up" some space rabbits and see what we get! (Hopefully not tribbles.)

Spin areas will surely become ubiquitous in all low gravity colonies.

Startup anyone?

Wild idea: build one on earth to simulate 1.1G (or higher; whatever would still be comfortable) and put gyms, hotels, swimming pool, living quarters, etc. in it. Being in it for extended periods of time would build up muscles and bones. That would likely be something that fitness people and professional athletes would be interested in. And it's a good dry run for building and operating these things on Mars and the Moon. If we can make these things work on Earth, making them work in lower gravity is only going to be easier as the g-forces would be lower.

A train or roller coaster on a slightly tilted circular track would probably do the job. A slight tilt would just move the gravity vector orthogonal to the floor.

The acceleration needed to make a turn with radius r at speed v is. v²/r (https://courses.lumenlearning.com/suny-physics/chapter/6-2-c...)

If that combined that with earth’s gravity has to give you 1.1g, that has to be (via the Pythagorean theorem) about 0.2g or 2m/s². Let’s pick r = 100m. Then, v² has to be 20, giving as a velocity of about 16 km/hour. r = 1km would require about 50km/hour.

Sounds doable, until you consider your “put gyms, hotels, swimming pool, living quarters, etc. in it”. That’s a lot of mass and space.

Centrifuges that we put potential astronauts and fighter pilots in are a lot smaller.

On the other hand, there’s the idea of “a massive floating railway, Maglev-style, which will travel along a track with a radius of 2.5 kilometers within an underground vacuum tunnel. The machine will run on excess energy generated from wind and solar, and it can reach speeds up to 2,000 km/h. When the renewable energy production is insufficient, the kinetic energy from the train movement will be reconverted and sent to the grid.” that engineers claim can be built (https://www.greenoptimistic.com/energy-train-mph/). That would hit over 10g and weigh a lot more than that hotel. I can’t find updates, though.

Reply to self: the MVP for this probably is to walk around with a backpack that’s 10% of your body weight.

That’s a lot cheaper and for many sports likely would bring the same benefits.

That's why I proposed using a train. Minus the swimming pool, totally doable to have one driving around at relatively low speeds. We use trains to move many tonnes of cargo around already. So, I don't see the mass as a show stopper.

https://en.wikipedia.org/wiki/Tilting_train

You don't need to have a tilting train, you can just tilt the track.

> build one on earth to simulate 1.1G (or higher; whatever would still be comfortable) and put gyms, hotels, swimming pool, living quarters, etc. in it. Being in it for extended periods of time would build up muscles and bones.

Is that any better than ankle weights? Or wrist, I suppose.

The difference between weights on your body and higher gravity field is that with higher gravity all of you feels the force equally at the same time, so you're not putting excessive strain on certain parts of your body while neglecting others (such as internal structures).

Spinning stuff in air takes more energy than spinning stuff in a vacuum.

You would likely put these in air on the moon as well. Depends a bit on your design.

If the track is enclosed in a smooth symmetric enclosure, either a circle or flat dome, the air within the enclosure will spin along with the train or other tracked constructions, instead of impeding them.

I imagine some texturing on the inside of the enclosure could create small scale surface turbulence that even reduces the minimal friction there.

But then we do operate trains in our atmosphere so this is a solvable problem. The advantage outside of our atmosphere is of course that aerodynamics don't matter, which indeed would make things more energy efficient. Also there would be no weather (or very little of it on Mars), no humidity.

Why did nobody do this yet? It would totally be a great prototype for stuff in orbit.

I just keep thinking about this short film[0] that explores the views you can see with rotational artificial gravity, and how nauseating it could be :)

[0] https://vimeo.com/869858712 also available as https://www.youtube.com/watch?v=iiPmgW21rwY

Just point the axis at the major body of interest, Earth, moon, Jupiter, etc., and it would slowly rotate in a stationary position, instead of spinning around you.

Or align the axis with the major light source if that is different, like the sun for inner solar system locations, and at least the lighting won't keep moving around.

Not much different from watching scenery go by in a vehicle then.

Closest thing I can think of is rotating houses / restaurants, but they go very slowly.

It would have to be big enough to avoid people getting dizzy, and even then it would still be a factor I think. That said, size/scale is less of a concern on the moon I would argue.

You inspired me to look up if there were many still going and I was saddened to discover there are no longer any operational ones left in the UK.

All parts would be spinning at the same angular velocity, so unless it's really far away from its centre of rotation (expensive, inconvenient) you'd experience more acceleration near the centre than at the edges.

Maybe that doesn't matter.

One of the commenters here has the right idea. Train riding forever on circular slanted track could easily house some living spaces, offices and gyms. You could book a stay there for few weeks and after that feel like you are walking on air once you come back to normal life.

Circular dome colony over a very large rotating space, running on concentric rings of superconducting rails. Spokes of slidable inner-outer weights to counter balance its residence’s movements.

Running on reliable constant nuclear power, from a safe distance.

Maximum gravity at the tilted edges. Only natural gravity at the center. Enter & exit from a tunnel that connects under the center.

Aside from the challenges of location & distance from Earth, if we can build small mobile cities on water (mega cruise lines) on the untamed ocean in Earth gravity, surely a small stationary spinning platter city in low gravity is possible.

I think humans are going to find out that one g has many uses besides health. Good for a lot of manufacturing too. Gravity is a stabilizer, vertical organizer, anchor. Just as low gravity will have many advantages. Being able to quickly “adjust” gravity, by moving location, will be significant.

> Being able to quickly “adjust” gravity, by moving location, will be significant.

Who is doing the adjusting and the moving?

I don't think you'd want to move anything large. You'd build eg your factory in the environment where it's best; and build a second factory in a different environment, instead of moving them around.

However, if you eg making computer chips, you might move those around between different environments, depending on the processing step.

Yes, I meant move materials and parts between g-force specific equipment.

If entire factories needed to "move" up and down in g-forces, they should be in their own variable spin bowls! Not sure what kind of factory that would be.

You probably know this already, but for a while people were toying with the idea of a "childbirth centrifuge". https://patents.google.com/patent/US3216423A/en

There's probably a reason it never caught on.

Reason one - We already have gravity here.

Reason two - Childbirth + vertigo? WTF!

Clearly they should have gone with a rudimentary linear accelerator such as a bungy drop or bouncing elevator type system!

While on the subject of inventions to aid with childbirth, I'll leave this here:

https://science.howstuffworks.com/science-vs-myth/everyday-m...

> Clearly they should have gone with a rudimentary linear accelerator

Like a railgun.

Also the subject of an opera. http://www.henryakona.com/the_blonsky_device.html

On the Moon, at normal pressure, humans shoud be able to get enough exercise in a jungle gym, or by donning a set of wings, flapping them to fly.

Given that there is some gravity, putting on a weighted suit to increase their mass would also make sense, although it'd be unwieldy if it's not distributed exactly the same. Plus, getting weight into space is expensive... although probably not as expensive as building a wall of death or spin gravity structure.

Why wall of death? It's gonna be just a neat cylindrical room with vaguely paraboloid walls. Even if you stop running suddenly, dropping down from 2-3 meters in 1/6 g shouldn't be anything more than inconvenient.

Weighted suit wouldn't help with the weight of your organs. They are accustomed to hanging inside you at 1g. Running on wall would provide them with that.

> Why wall of death?

I think that's just what the cylindrical room is often called when it's used for motorcycles. The paper repeatedly references it, abbreviated "WoD." I don't think there's any death involved. :)

I was going to say “I’d be surprised if organ support is a large issue to an adult. We already have long term astronauts and people who are bed ridden for a long time during recovery. I would expect an issue during development though.”

Turns out there is research in this direction: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2379624/pdf/can...

It seems to say that there is a long term impact on connective tissue hardening… but it blames lack of stretching; not lack of downward force. Any regular movement would seem to fix that.

However, internally, organ tissue probably ‘bounces’ more due to gravity during movement… so less gravity means less flex of connective tissue.

TLDR: you seem to be right

> long term astronauts and people who are bed ridden

And those people lose a lot of bone mass, muscle mass, and need physical therapy to get back to normal function in 1G. Two months of bed rest will absolutely ruin you. There's a good reason astronauts need to be fit to begin with!

6 months in space causes bone loss equivalent of 20 years of aging. Return to Earth, do physical therapy for 1 year, and you're still "10 years older" as far as bone loss goes. (https://www.sciencenews.org/article/space-bone-loss-density-...).

Generally, as far as I know, bone growth is triggered by impacts (think running etc), and is hard to stimulate with just muscle exercises.

> Generally, as far as I know, bone growth is triggered by impacts (think running etc), and is hard to stimulate with just muscle exercises.

Maybe they should do jumping while being pulled "down" by rubber bands.

The current microgravity solution is a treadmill for running that rubber bands pull you down to.

There are rocks on the moon. You don’t need to bring weights from earth.

I assume they’ll eventually just build a big gravitron. The seals would be tricky (I guess the axle it spun on could contain a ladder and door?)

Of course they could simply stop spinning it whenever they needed to open an airlock.

(Or just put it in orbit, where these problems are easier to deal with and you don’t need to deal with day/night radiation shielding/heating.)

Spin gravity in orbit has its own issues. Most notably you can't anchor the structure anywhere, so won't spin around the spin axis you want but around its center of mass. A center of mass that will shift as people move around, equipment is moved, etc.

Another issue is that you need a certain scale, otherwise the Coriolis force as well as differential gravity (the gravity at your feet being higher than that at your head) lead to disorientation and comfort issues. The lower limit seems to be about 40 feet, incidentally the size of a typical graviton on carnival on earth. That's quite a bit wider than the typical rocket, and for now we are much more comfortable with assembling stuff in a gravity well than in orbit.

> That's quite a bit wider than the typical rocket

You can have two habitats connected by a center tube, like an I. Rotate about the center of the I. Or a habitat and a cable connected to a counterweight.

It's not really necessary to build a wheel.

In orbit, you don't even need the tube, it can be a single habitat with retractable cables attached to a counterweight of useful material that isn't immediately needed.

The rotation axis could be stabilized actively by shifting counterweights. But the dynamics of the structure change depending on whether the counterweights move radially or tangentially. Rotation speed would fluctuate slightly in either case. This sounds like an interesting control problem!

It could be a blown up multiwalled sphere with the heavy equipment in a solid cylinder in the middle. The walls would naturally be a bit bouncy, if under the pressure of the internal air.

A big arena for playing professional sports could make a significant amount of money through televised sporting events.

Just put a centrifuge under a static dome. No seals needed.

In the Luna series they discuss this, they basically have a central axis where you enter and then can 'step' up higher to faster spin rates/more gravity (basically a tapered cone)

It's easier in space. I suspect it will happen there first and predominantly.

You know you have to fly all this stuff up there, right? You can dig out one of these pits with a shovel.

Self-sufficiency off-world is going to be much easier if people are healthy and happy.

A "gravity gym" is going to be basic healthcare. Wherever we go for the long term, we will ship and/or construct them.

Separate facilities for work and life, interconnected by a rollercoaster commute. What else has sci-fi left out?

Yeah, that's what they said, a self sufficient way of constructing a gravity gym.

[dead]

> Moon-based centrifuges allowing locomotion inside would pose technical challenges and demand substantial electrical energy.

Comments:

> would pose technical challenges

That's a very funny disadvantage to call out! "Technical challenges" are how you know you are on the moon.

A stable rotating system would seem to be one of the simplest possible lunar challenges. If it is implemented within an existing environment shell, it could be quite low tech.

> demand substantial electrical energy.

Maintaining rotation in low Earth gravity should be a very low energy process. The only energy loss would be friction at the point of rotation, which should be minimal, and some position controlled weights, for maintaining balancing in the context of human movement.

But the proposed no-tech solution has a great return on investment, and is realistic for early days, or infrequently inhabited outposts.

Finally I get to be that guy in the comments with a weird about of relevant experience. I built the world's largest hamster wheel in 2012[1], a large rotating circular platform ~6m in diameter.

It was a fun and unique experience to run on for a short amount of time, but most people would get dizzy after a few minutes of jogging on it. The curved platform also turned out to be a bit of a tripping hazard. It was more often used as a sort of swing (could this work on the moon?).

I'm skeptical that the experience on the moon will be much better, especially since the diameter they're proposing is even smaller.

1. https://sdusd-newsfeed.blogspot.com/2012/09/pt-loma-high-sen...

With a hamster wheel, aren't you basically running in one spot near the bottom? If so, do you know what causes the dizziness?

Because you're looking forward at the platform that's moving down and toward you. Kind of like if you were to stare down at the belt of a treadmill while it's moving - it would be disorienting after a while.

Doesn't this boil down to a claim that blind people are incapable of running on a constant upwards slope due to motion sickness?

Because even if your claim is correct, and the conflicting visual input is disorienting, the Moon-dweller on a similar contraception could just close their eyes.

Staring down is not equivalent to being blind. Motion sickness occurs when signals from your eyes (like the motion of the world around you), body (like wind on your face) and auricular semicircular canals (organs in your ear that sense acceleration) conflict with one another. In theory, your brain reacts to this with nausea because historically that situation would mainly arise due to illness or poisoning, so it might be good to vomit. That's why you can sometimes alleviate car sickness by opening a window (convincing your brain that you're definitely moving) or, if you're driving at constant speed, refraining from looking out the window (convincing your brain that you're stationary).

Blind people only have 2 out of the three signals so they might be less prone to motion sickness.

If this dizziness is anything like VR sickness, you can become acclimated to it.

And you might actually just wear VR (or augmented reality, AR) goggles to counteract it.

Is there a reason something like a water rower wouldn’t work on the moon? Possibly with a weighted vest or a weighted seat.

Rowing is pretty full body and doesn’t seem that reliant on gravity.

I'm always baffled that these studies don't put more emphasis on resistance training, since the main issue is that your body no longer has to resist the forces of gravity on a day-to-day basis.

In theory exercises like the major compound lifts should go a long way because they stimulate almost every muscle in the body. You get a lot of sustained muscle growth out of doing big lifts even just 2-3 times of week.

Of course you're not going to be literally lifting weights in space because they're weightless! But resistance can be produced with bands, pneumatics etc.

Rowing is a really good one because you get resistance training and cardio at the same time.

But the Moon does have gravity, just less of it. Is no one considering just squatting and deadlifting huge-ass boulders? Fill a big basket with moon rocks and eventually it's gonna be heavy...

> In theory exercises like the major compound lifts should go a long way because they stimulate almost every muscle in the body. You get a lot of sustained muscle growth out of doing big lifts even just 2-3 times of week.

Keep in mind that you are doing your 3 squat sessions a week on top of a whole week of lugging your own body around in 1g.

NASA has IRED for resistence training on ISS. IIRC regiment was ~1xBW squats/deadlift for 3x10s in space every few days. Upper body was even more "normie" strength requirements. I think the routine included many hours of resistence training in general with very conservative weights to maintain mass and avoid injury at all costs.

I have read about IRED but never heard the particulars of their training regime before. Dunno about that workout plan, it is a workout which would not induce hypertrophy on earth, so I wouldn't expect it to do much in zero g. Hopefully they don't give up on the idea just because they were doing weak lifts

Really though when they get to the moon I just want to see them bring a barbell and two big buckets which they fill up with moon rocks. In general free weights are better for hitting a variety of muscles at once vs machines being better for isolation exercises, if you're trying to prevent muscle wastage across your entire body, a barbell may very well be superior!

I looked list of artificial objects to lift on the moon.

Lunar Roving Vehicle curb is only 76lb/34kg. That's would be a fun OHP set.

The Descent Stage of Lunar Landing Module is 358kg/789lb. Probably strong man car squat with one of the legs for reps.

Many landed probes/landers between the 1-5 plate territory territory.

>if you're trying to prevent muscle wastage

I actually like all the new light weight resistence cable machines that perfroms like IRED released in the last few years. But a 24 ft barbell with 10 ft of mooncrete bumper plates on each side to replicate a 5plate pull would be neat.

I think the NASA goal is to build up muscle base on earth and do least impact/injury risk routine to preserve muscle mass and bone density. I'm assuming it's not bro science, and they have injury table for astronauts who are genpop fit but not lifter strong, and optimizing for that. I wonder what their policy on steriods is.

Well, if nothing else there's a lot of basalt lying around on the moon, which would weigh about 3,000 kg/m3 on earth. That means it should weigh around 500 kg/m3 on the moon. So you're gonna need some big plates, but getting up to the amount of weight they have people lifting on IRED sounds pretty doable. This way all you have to send over from earth is a bar and some buckets!

>>~1xBW squats/deadlift for 3x10s

For super-fit astronauts, that's pathetic.

Dunno why this is being downvoted because it's correct. In their 20's most people can be at this level by their second session in the gym

But you also want to have impact shocks, like your foot hitting the ground, to stimulate bones. Resistance training is certainly helpful, and perhaps a rowing machine could be modified to give you that shock to the legs, too.

Resistance training doesn't just grow muscles, it stimulates bone growth as well.

That's why it's recommended for osteoporosis.

Resistance training is, of course, 100% what astronauts already do on the ISS; how to optimally exercise in zero gee (and cramped conditions) has been extensively studies for half a century now. So it’s kind of understandable if some one wants to study a mode of exercise that works on the Moon and is not resistance-based.

A rower wouldn’t provide the same impact forces on the feet, a key driver of the physiological processes that maintain bone density in the legs, hips, and likely even spine.

Forces from the muscles are the main bone stimulator. Running in low gravity would probably use less muscle force then a rowing machine.

They do mention that an erg doesn't have the full effect wanted:

> Low-intensity steady-state exercise or high-intensity interval training on ergometers may serve to preserve cardiorespiratory fitness [12,25–27] but have little impact on muscle and bone mass.

I wonder if they use a rower on the ISS.

[dead]

The book "Imperial Earth" by Arthur Clark featured a circular cycle track on a low-gravity spaceship.

The main protagonist was trying to train for earth gravity so he cycled around it very fast until he felt 1G

There was a zero G running track in the movie "2001: A Space Odyssey"

Reminded me of circular wall running in 2001 Space Odyssey more than 50 years ago: https://youtu.be/1wJQ5UrAsIY

If he ran in the same direction as the station was rotating then he would feel extra force pushing him into the ground, whereas running the other way would cancel some of the centrifugal force. I wonder if the directions would feel like 'uphill' and 'downhill'. I assume for training purposes you would probably want uphill. I don't know if the movie gives you enough information to work out which way the spinning section is going.

Running around in circles sounds like a great way to fight boredom. Right next to their aptly named Wheel-of-Death device there's an entire room dedicated to paintwatching, which is a bit like birdwatching, or at least so says the promotional material.

Shades of 2001: A Space Odyssey

>>Long-lasting exposure to low gravity, such as in lunar settlements planned by the ongoing Artemis Program, elicits muscle hypotrophy, bone demineralization, cardio-respiratory and neuro-control deconditioning, against which optimal countermeasures are still to be designed. Rather than training selected muscle groups only, ‘whole-body’ activities such as locomotion seem better candidates,

I don't get why whole body locomotion would be the best way to combat muscle hypotrophy and bone demineralisation when that is not the best method on earth.

A better approach would be using bands or even moon rocks to lift weights etc.

Just set new lunar records for the deadlift, squat etc.

> I don't get why whole body locomotion would be the best way to combat muscle hypotrophy and bone demineralisation when that is not the best method on earth.

Whole body locomotion is approximately the only way we have ever tried on earth to combat muscle hypotrophy. So we don't know whether that's the best method or not: we just haven't tried anything else.

To be more precise, any method we have tried on earth, be that bands or weight lifting etc _also_ included a hefty dose of whole body locomotion inside a strong gravity field.

(You can get great results from hitting the gym for squats and deadlifts three times a week for an hour. But that regime also includes 24/7 exposure to 1g of gravity.)

Got you. So we would need to do the experiment to try resistance training in low/no gravity to see whether it would work or not.

It would seem like the obvious thing to try though as it is the best method in regular gravity.

Oh, it's definitely something we should try. We need a lot more experiments.

The only thing we know for sure is that moving around in 1g is generally enough for our bodies. Especially once you throw in a bit of deliberate exercise. We also already know from our space stations that 0g is bad for you, and even exercise can only mitigate some of the damage.

But that's already the limit of our definite knowledge.

But we don't know where the boundaries are, and whether the transition is smooth. Eg I would suspect 0.01g to be still pretty bad, and 0.99g to be indistinguishable from earth for our bodies. But would 0.9g be enough? Probably yes, but who knows? What about 0.5g? Is it bad? Is it 50% as bad as 0g?

Would 0.2g give you 80% of the benefits of 1g? We don't know.

Possibly dumb question, but if you wore weighted vests (for example) to match the same force due to gravity on earth for that individual, would that be equivalent to existing on earth without the vest? Ignoring e.g. the difference in exact distribution of the weight.

There are some differences, eg how your organs sit inside your body.

Perhaps your liver works best in 1g? We can make some educated guesses, but honestly we don't know! No one has run experiments.

Skateboarding on the moon is going to /killllll/.

Swimming would be a pretty interesting experience as well. You probably could even walk on water.

https://what-if.xkcd.com/124/

https://en.wikipedia.org/wiki/The_Menace_from_Earth

I'm not sure how realistic the muscle-powered flight is, but a different form has been done on Earth.

I spent so many years riding bikes in circles on a velodrome. Doesn't seem too different.

When I would ride behind a motorbike, at 40+ mph, it was effort to just keep my body from being pushed down into the handlebars. At 50+, my tires would start to skip upwards/outwards.

Keep in mind if you are putting in enough speed to get rotational acceleration of 0.5 G on Earth, that would be around 1.3 - 1.4 G total acceleration (depending on the bank angle). But on the moon it would just be 0.5 - 0.6 G.

Very interesting point, thanks!

Velodromes already seem cool to me, so a velodrome on the moon seems cool as hell.

One question I have that I didn't see addressed in the article: how does the inner ear work in low gravity? I wonder if this might make astronauts unusually dizzy on the moon because of differences in the vestibular system.

This article seems like a good survey of the general impact low-g has on the inner ear changes, but I've barely skimmed it: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8595211/

There have been studies on the subject, and participants could adapt to rotations as high as 23 RPM. In this test they were more in the 5-10 RPM range (depending on which iteration and how fast the participants were running), so it'd probably be fine after some adjustment.

https://pubmed.ncbi.nlm.nih.gov/14703662/

That is interesting, but my concern is a bit different than that article - I'm worried about what happens when the astronaut stops. After they are done running, they will be at rest in a low-g environment (unlike this experiment), but their inner ear fluid will have most of the momentum it had while they were running - this is the physiological basis of merry-go-round dizziness.

On earth the fluids quickly settle and the dizziness fades. I wonder if maybe it would take considerably longer on the moon. It is probably something they can adjust to, but I was wondering.

I doubt they'd just stop. I imagine in practice this would be more of a parabolic track, and they'd slow to a jog after the peak of their workflow. That would give time for their cochlear fluid to slow down as well.

And even that aside, I'm not sure the lack of gravity would change how quickly cochlear fluid settles. I think that settling is due to resistance from the fluid turbulence of the cochlear canals, not due to gravity.

Could you do this in zero-G, too? This seems like a lot simpler than trying to have a section of a space station rotate and maintain seals around it.

You might like this video from Skylab: https://youtu.be/S_p7LiyOUx0?si=J_JqunYl2OkeROa7

(23 second mark)

I think having some level of gravity is important for the simplicity of it. With a downward force it acts somewhat like a velodrome. You start angled upwards and as you gain centripetal force you gradually go more and more horizontal.

Theoretically you could achieve the same result in zero-g, but getting started is much more difficult, as are microadjustments in speed and balance.

Would running prevent deconditioning in muscles that aren't stressed by running?

Running in a circle like this would temporarily give the impression of higher gravity which would affect all muscles.

That makes sense, thanks. So the claim here is that exposure to a force similar to Earth gravity for "a few laps a day" would prevent/reduce whole-body deconditioning?

I guess that makes sense too, since a few reps of weightlifting every couple days is enough to trigger muscle growth and bone densification.

In a circle, you're in an accelerating reference frame and in theory your body can't tell the difference.

The amount of exercise you would have to do to even begin to remotely keep up with earth's gravity is insane.

Separately, how does aging fair with zero g? can really old people live longer up there or is it actually worse?

Our bodies are exquisitely optimized for the surface of the Earth. Any deviation from that (gravity, sunlight, gas pressure, gas composition, radiation, etc.) is likely to be deleterious.

This does not bode well for expanding out into the solar system. It might only work if we do some genetic engineering to make off-world habitats more habitable.

> It might only work if we do some genetic engineering to make off-world habitats more habitable.

Regular engineering, of robots, will probably work first.

Is this the same concept as the running scene in the film 2001: A Space Odyssey?

Actually no. In the movie, there is already gravity present in the hub - generated by rotating this large cylindrical hub. Running in such hub would increase gravity slightly but no running is needed at all! Just being in such hub is comparable to running in cylinder mentioned in the paper.

Running in small (10m) diameter cylinder increase gravity significantly without need to spin the cylinder.

Anyway to minimize effects of Coriolis force in spinning cylinder, I think that the size of the cylinder would be significantly larger than the size in the movie.

Are you thinking of the space station? The running scene was in the interplanetary ship, with a 12m diameter cylinder spinning just enough for moon-level gravity. https://en.wikipedia.org/wiki/Discovery_One

Whenever I see horizontal running I thought of Sir Humphrey and the Christmas special.

Will we ever put men on the moon (again)? It’s been 52 years

That’s the plan: https://en.m.wikipedia.org/wiki/Artemis_program

It's very expensive. The plan needs serious improving.

Looks cheaper than the Apollo program when adjusted for inflation (Apollo was $257 billion in 2023 dollars)

If you want to make it look even cheaper, you can adjust for GDP growth instead.

(It's still very expensive in absolute terms, and you can have a discussion about whether it's really the best use of tax payer funds.)

Now I envision a multi-story lunar habitat with a 30 foot diameter well that you have to run on to get from one level to the next. At least to get up. Getting down may just involve jumping down.

For the life of me I can't visualize how this would with in practice at all.

Probably something like this guy running out of a ditch: https://m.youtube.com/watch?v=cfXTElHLT_I

https://www.youtube.com/watch?v=L5yislIOui8

A carnival show where a motorcycle rides inside a conical well.

In lunar gravity you can probably do (some of) it without the motorcycle.

It would look a lot like the circular running track in SkyLab: https://www.youtube.com/watch?v=qiMq-fdRhLo

But probably on a slight angle so the sum of the centripetal force and the moon's gravity is along the body axis.

Or perhaps a bowl shape that you climb up the sides of as you speed up.

There are pictures in the article of their test setup with someone running on the wall which might help

[flagged]