Hamster wheel gravity

[todofwar]

Was thinking about the whole artificial gravity thing, and about the usefulness of inflatable modules thing, and realized the two might work well together. The general problem with inflatables is you need to fill them with stuff, so really what good does the inflatable part do for you except require multiple launches? So I thought maybe just having some big empty space for astronauts to feel a little less claustrophobic would be nice. And maybe put some excercise equipment in there too. And that's when I thought, hamster wheel. If you make a wheel 5 meters across, and tether someone to the middle of it, and they start running, then if they hit 8 miles an hour (that's not bad at all really), their feet will experience 0.5g of centripedal force. Now, they will feel some tidal forces. Their head will experience about .1g in this scenario. Running at 12 miles an hour (5 minute mile pace) gets their head up to .23 and their feet to 1.2. Basic idea is, launch an inflatable with a five meter diameter internal environment. Have a pole run through the center, and a tether attached. It might need to be able to swing the person a bit to get them started, but once they're moving they should be able to propel themselves forward. Nice, lightweight 0 energy solution for artificial gravity for long term habitation. So, for anyone with more knowledge about medicine, the question is, would simulating gravity by running in a circle have any benefit? I'm thinking thirty minutes to an hour a day (probably not all at once) should help somewhat. They already have those bungee chord treadmill things after all. 

Optional design: Make it a bike attached to a rail, easier to get to speed and keep the body more prone to avoid tidal issues.

Possible issue: The mass of a grown human running around will throw off the center of mass, and will introduce some angular momentum to the station. Might need to be compensated with something. Maybe the bike solves this a little bit, just add a counter weight to at least preserve a center of mass. If gravity is an issue on the Moon or Mars though, at least those won't be problems.  

[Steel]

Second issue: have you seen footage of astronauts walking on the moon? The lack of gravity really slows you down. So I'd imagine running at 8 mph with an average of 0.3 g might be quite a challenge

Edited December 18, 2016 by Steel

[James Kerman]

It sounds like a great idea however wouldn't you have issues with the opposing forces created during the run?

Also could it be improved by adding a generator as a resistive force?

[magnemoe]

56 minutes ago, Steel said:

Second issue: have you seen footage of astronauts walking on the moon? The lack of gravity really slows you down. So I'd imagine running at 8 mph with an average of 0.3 g might be quite a challenge

Think it was more the stiff heavy and top heavy space suits who it would be dangerous to tumble in who slowed them down. 
You would be faster on moon if you had atmosphere, not at short distance where traction and power to legs is important but for an long distance run it would be easier

Astronauts on Skylab did the hamster wheel even is station had smaller diameter and did not rotate. 
And is an fun idea
 

[Thor Wotansen]

The other problem is if the wheel is spinning and the astronaut is the motor then the astronaut feels no Gs because he/she remains stationary.  sure, the spinning bit feels Gs but the astronaut isn't spinning.

[todofwar]

46 minutes ago, Thor Wotansen said:

The other problem is if the wheel is spinning and the astronaut is the motor then the astronaut feels no Gs because he/she remains stationary.  sure, the spinning bit feels Gs but the astronaut isn't spinning.

No, the wheel is stationary the whole time, the astronaut runs around generating their own g force. Think of it like a car going along the side of a track, the faster it goes the harder its pressed against the track wall. From an observer outside, what is happening is the astronaut is propelling themselves forward to collide into a wall, but instead of colliding they redirect themselves along the wheel. Faster they propel themselves forward, harder they "hit" the wall. Much the same way a runner is doing little more than falling forward and catching themselves over and over again. 

 

Now that I think of it, some kind of rigid bar for the astronaut to push against as they get themselves going will probably be better overall than a tether. That way, while running slower, they can push themselves into the wall for some added traction. As they really get going they won't need to push themselves down anymore. So some kind of trapeze type bar hanging down on a rigid rod from the center of the wheel. 

4 hours ago, James Kerman said:

It sounds like a great idea however wouldn't you have issues with the opposing forces created during the run?

Also could it be improved by adding a generator as a resistive force?

Yeah, that's one of the issues. The section of the ship would need to weigh enough to make the astronaut's mass almost negligible. Don't know just how massive off the top of my head though. 

[DBowman]

here is some Skylab footage of what you have in mind. Seems like a good idea if you have the space. Also stuff like throwing heavy medicine balls to each other would be good inertia driven exercise.

[kerbiloid]

Resin bands to press them to the wheel. (Otherwise there would be no friction between the boots and the wheel.) 
And ten spacemen are running rotating the wheel, while one sits in a chair watching TV.

[Shpaget]

Wouldn't they keep on falling on their noses? It is far to small wheel. Coriolis would have them barf in no time.

[todofwar]

6 hours ago, Shpaget said:

Wouldn't they keep on falling on their noses? It is far to small wheel. Coriolis would have them barf in no time.

They apparently did it in space lab, not sure how big that was. I'm thinking a harness would be needed to train on it at first, but over time humans are capable of pretty impressive things.

[magnemoe]

40 minutes ago, todofwar said:

They apparently did it in space lab, not sure how big that was. I'm thinking a harness would be needed to train on it at first, but over time humans are capable of pretty impressive things.

Looks like diameter was around 5 meters, over an meter from head to the center rope. Did not see the start of run clearly but it looks like he started on all four gripping the wall. as you get some speed you stand up as you get pushed outward. 
How it felt, well I guess somebody asked the skylab crew. Guess it felt more like acrobatic than real running. 
 

[Jonfliesgoats]

I think they experimented with this, sort of, on Skylab.  They were running on a fixed, circular part of the structure.

What Tod said.  I posted before I scrolled.

 

1 hour ago, todofwar said:

They apparently did it in space lab, not sure how big that was. I'm thinking a harness would be needed to train on it at first, but over time humans are capable of pretty impressive things.

 

[wumpus]

58 minutes ago, magnemoe said:

Looks like diameter was around 5 meters, over an meter from head to the center rope. Did not see the start of run clearly but it looks like he started on all four gripping the wall. as you get some speed you stand up as you get pushed outward. 
How it felt, well I guess somebody asked the skylab crew. Guess it felt more like acrobatic than real running. 

I've heard reports that Skylab astronauts hated exersize, but not the same from ISS.  Some of this might be cultural change, but I suspect the newer exersizes make more effort to get the sweat from pooling on your body.  There's a pretty good mockup* of Skylab in the Smithsonian (downtown): it doesn't look big enough to run in.

* don't know how real the command module body is: I suspect one of the last two was part of Skylab and the other is in the intact Saturn V in Florida.  Most things in that museum are the real deal or (for things that didn't come back to Earth) backup copies.

[todofwar]

1 hour ago, wumpus said:

I've heard reports that Skylab astronauts hated exersize, but not the same from ISS.  Some of this might be cultural change, but I suspect the newer exersizes make more effort to get the sweat from pooling on your body.  There's a pretty good mockup* of Skylab in the Smithsonian (downtown): it doesn't look big enough to run in.

* don't know how real the command module body is: I suspect one of the last two was part of Skylab and the other is in the intact Saturn V in Florida.  Most things in that museum are the real deal or (for things that didn't come back to Earth) backup copies.

Interesting. I would think running in the hamster wheel would get sweat to actually flow down off of you like it would naturally, since you are in effect running in 0.3g. Maybe getting in one of these:

Instead might work better. You can get going up to a faster speed, getting closer to 1g, and with the added benefit of having less tidal force. And, you can bolt it onto a track, so you can start from stationary allot easier. Downside is, your legs won't get the same level of force as they would from walking around in a 1g environment so who knows what that will do for bone loss. 

Whole point of this is to accomplish something close to 1g for health reasons, without the need for a complex rotating hab which needs to be much wider due to the RPMs necessary at smaller radii. But if it's only an hour or so at a time, I think a small 5m diameter wheel might work nicely. 

[mikegarrison]

I would think that when the astronaut starts running, it would induce a counter-spin into the structure (the magnitude of which would depend on the relative moments of inertia.). But when the astronaut stopped, the result would be a negation of that counterspin. It's not velocity that causes forces, it's accelerations.

 

(Fiction alert: in the novel Exo, one of the characters does this in their space station. But the station is stabilized by a large tethered weight, thereby using tidal forces to keep it always locked with respect to the Earth. So a little bit of running around inside is probably no big deal.)

Edited December 19, 2016 by mikegarrison

[p1t1o]

Relevant:

" The Apollo 12 crew moved over distances of 200 to 300 meters between geology stops and, on at least one occasion, had heart rates of about 160 beats per minute. On the three long missions, the astronauts wore suits with waist convolute added so they could sit on the Rover; and an added benefit of the waist convolute is that it gave them more leg flexibility. On Apollo 17, Jack Schmitt and Gene Cernan ran comparable distances and experienced heart rates of no more than 120 to 130 beats per minute. Several of the J-mission astronauts achieved sustained running speeds greater than 5 kilometers per hour and there seem little doubt that, with some avoidance of uphill running, they would have had no trouble achieving the 3.6 kph average speed assumed by planners for an hour-long walkback from a failed Rover, or the 2.7 kph average speed assumed for walkbacks of over an hour. "

 

https://www.hq.nasa.gov/alsj/a11/a11.gaits.html

[Gianni1122]

On 12/18/2016 at 3:53 PM, todofwar said:

Possible issue: The mass of a grown human running around will throw off the center of mass, and will introduce some angular momentum to the station

Correct. This is exactly why all exercise equipment on the ISS is on some sort of vibration isolation system.

 

On 12/18/2016 at 3:53 PM, todofwar said:

would simulating gravity by running in a circle have any benefit?

"Simulating gravity" for the astronauts comfort or for the astronauts health? We have already figured out how to simulate gravity (more like resistance) via the T2 treadmill etc. in order to prevent them from losing muscle mass etc. So unless there were benefits other than mental/physical comfort; such as, power production, experiment conducting and of course additional storage, the cost to implement and increased size leading to a higher risk to threat orbital debris probably couldn't be justified. However, I'm sure the astronauts would appreciate it.

I'm referring to microgravity off-planet. On the surface, you could argue some other possible benefits.