Poll

How long does a manned mission have to last for a spin gravity (SG) solution to become routine?

All manned spaceflight will implement SG within minutes/hours of achieving orbit
SG implemented for durations greater than a week (i.e. not for cislunar transits)
SG implemented for durations greater than 6 weeks  (i.e. not for NEO rendezvous)
SG implemented for durations greater than 14 months (i.e. not for Mars missions)
SG implemented only for longer durations (5+years)/or not yet by 2100
SG is unnecessary with appropriate exercise

Author Topic: Spin gravity to 2100: over what transit time will SG become routine?  (Read 4074 times)

Online mikelepage

Is there any medical research on some drug to "disable" the vestibular system in a way that the brain ignores inbalance information?
This is useless on earth because people would just drop to the ground without the balance information, but in zero-g it could work. People would lose ability to "feel" attitude but perhaps visual cues would be enough.

I know they're working on such a drug for Meniere's disease (a horrible disorientation sickness), but as far as I know they've only managed to treat the symptoms.  The sense of balance is very primal.

You are taking into account that the whole ring is trying to fly apart, right? Each hinge has to be strong enough to hold the entire mass together, just like with a chain.

Love the design btw. Do you make the hinges strong enough to support the spinning vehicle, or do you add nuts and bolts after deployment?


Cheers.  You may have noticed the small nodules on the center-top/inside of each segment/wedge? The vision is that these will have retractable tethers that take the load, whilst the hinges articulate the movement only.  Depending on how many segments there are (12 in this case), some of these will be replaced by hatches with inflatable tubes to the axial modules.   Having said that, there's nothing to stop the hinges from being quite robust also so they can take some of the load if necessary.

In principle, once such a system is set up, I see no reason to bolt it.  Why shouldn't such an array deploy and retract multiple times per mission (possibly maintaining angular momentum with a flywheel)?  Retract and lock when it comes time for trans-mars/lunar/NEO injection burns, but deploy and spin for cruise phases.  Docking hatches at the ends of each wedge segment will dock to each other when deployed, but can dock to axial modules when retracted.

I've attached a video with a 3D print I created of this exact design (and can make it available through my shapeways shop if anyone's interested - pm me).

Online Coastal Ron

  • Senior Member
  • *****
  • Posts: 3230
  • I live... along the coast
  • Liked: 2055
  • Likes Given: 2454
...so I suspect they'll be [i.e. ITS] over-engineered for the much gentler stress of AG.

Well then, all you need to do is to convince Elon Musk to spare two of them for this experiment...  :D
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online mikelepage

...so I suspect they'll be [i.e. ITS] over-engineered for the much gentler stress of AG.

Well then, all you need to do is to convince Elon Musk to spare two of them for this experiment...  :D

Somewhat anti-intuitively, if you could attach two ITS "tail-to-tail" (main engines facing each other), and adjust the internal crew-space to match, you would have a much larger radius to work with for a tumbling pigeon style arrangement.

Offline Paul451

  • Full Member
  • ****
  • Posts: 1208
  • Australia
  • Liked: 590
  • Likes Given: 510
Minor aside:

if you could attach two ITS "tail-to-tail" (main engines facing each other), [...] you would have a much larger radius to work with for a tumbling pigeon style arrangement.

I may be using the terms wrong, but I generally say "Tumbling Pigeon" for a single-ship rotating end-over-end, borrowing from Heinlein's juvie stories. Likewise a habitat still attached to its upper-stage. Hab at one end, propulsion at the other.

But if you attach things together in a line, still spinning end-over-end, I usually say "baton" (or baton-style). Dual ITS would therefore always be a baton.

I can't recall a useful term for something spinning around its long axis, I've been saying "cylindrically". ("Roll" doesn't seem sufficient.)

Wheels (especially "spoked wheel") and rings should be obvious. Not sure if "hub'n'spokes" is too confusing for a configuration where there's no wheel, or if there's another term?

Online mikelepage

Minor aside:

if you could attach two ITS "tail-to-tail" (main engines facing each other), [...] you would have a much larger radius to work with for a tumbling pigeon style arrangement.

I may be using the terms wrong, but I generally say "Tumbling Pigeon" for a single-ship rotating end-over-end, borrowing from Heinlein's juvie stories. Likewise a habitat still attached to its upper-stage. Hab at one end, propulsion at the other.

But if you attach things together in a line, still spinning end-over-end, I usually say "baton" (or baton-style). Dual ITS would therefore always be a baton.

I can't recall a useful term for something spinning around its long axis, I've been saying "cylindrically". ("Roll" doesn't seem sufficient.)

Wheels (especially "spoked wheel") and rings should be obvious. Not sure if "hub'n'spokes" is too confusing for a configuration where there's no wheel, or if there's another term?

Yes, the nomenclature is a bit fuzzy.  Can't say I'd ever really thought about it, but I do tend to use "tumbling pigeon" to refer to a single pressure vessel (counter-balanced or not) spinning end over end. "Baton" I think you're right, refers more generally to any arrangement where the longest dimension of the craft is designed that way for the purpose of achieving a large spin radius (which still spins end over end).

I think of the "cylindrical" habitats (spinning around long axis) as just a special case of "torus" habitats, where the donut has no hole.  The only cases where I've seen them proposed is where there is a name of the specific design. For example there is the Kalpana One design by Al Globus et al, which is an evolution of the O'neill cylinders. 

I don't particularly like them because they tend to use single large volume pressure vessels, which must be built in their entirety before they can even start being useful.  Making them small enough to be feasible requires the occupants to tolerate higher spin rates for a given launch mass/acceleration level.

I would add that there is another spinning geometry I developed for the 2016 NASA space apps challenge - the "spiral space station" twin spiral framework geometry - which I like as a model for space habitats around asteroids, because it can feasibly keep growing/renewing itself as long as resources are available. 




Offline blasphemer

  • Member
  • Posts: 80
  • Slovakia
  • Liked: 23
  • Likes Given: 84

Zero-g adaptation disables the vestibular system anyway. Once you've adapted, you just don't get dizzy any more.

Offtopic, but I wonder if this would make zero-g adapted people immune to other sources of dizzyness, such as simulator sickness? It is a big problem in virtual reality, and the reason why many VR apps/games heavily restrict player movement or use teleportation instead of natural, continuous movement.
« Last Edit: 08/25/2017 10:11 AM by blasphemer »

Offline blasphemer

  • Member
  • Posts: 80
  • Slovakia
  • Liked: 23
  • Likes Given: 84
I made a quick mock up picture of two 9m diameter ITS spaceships (ship length 37m) connected by an almost 200m long cable. This should enable near 1g gravity at a comfortable 2 RPM rotation rate.

« Last Edit: 08/25/2017 12:39 PM by blasphemer »

Offline Lampyridae

  • Veteran
  • Full Member
  • ****
  • Posts: 1641
  • Liked: 64
  • Likes Given: 114
If you're going to have any kind of volume of commercial passenger spaceflight, people will want artificial gravity.

How much? Enough to ensure that poo breaks off and goes into the toilet, bone demineralisation and other serious issues be damned. You only need a small centrifuge to handle that, and a galley/sit-down area for eating and exercise, maybe cabins - sex in zero-g seems about as practical as trying to swim through air. That could be Discovery centrifuge size even though it goes outside Theodore Halls' comfort zone - it's only an AG area.
SKYLON... The League of Extraordinary Gentlemen's preferred surface-to-orbit conveyance.

Offline IRobot

  • Full Member
  • ****
  • Posts: 1151
  • Portugal & Germany
  • Liked: 204
  • Likes Given: 189

Zero-g adaptation disables the vestibular system anyway. Once you've adapted, you just don't get dizzy any more.

Offtopic, but I wonder if this would make zero-g adapted people immune to other sources of dizzyness, such as simulator sickness? It is a big problem in virtual reality, and the reason why many VR apps/games heavily restrict player movement or use teleportation instead of natural, continuous movement.
Put them on a sailboat for a week in the Atlantic. Either it cures motion sickness or you die from dehidration :)

Offline IRobot

  • Full Member
  • ****
  • Posts: 1151
  • Portugal & Germany
  • Liked: 204
  • Likes Given: 189
I made a quick mock up picture of two 9m diameter ITS spaceships (ship length 37m) connected by an almost 200m long cable. This should enable near 1G gravity at a comfortable 2 RPM rotation rate.


How do you cancel the whobbling due to people moving around the ships?

Online Coastal Ron

  • Senior Member
  • *****
  • Posts: 3230
  • I live... along the coast
  • Liked: 2055
  • Likes Given: 2454
I don't particularly like them because they tend to use single large volume pressure vessels, which must be built in their entirety before they can even start being useful.  Making them small enough to be feasible requires the occupants to tolerate higher spin rates for a given launch mass/acceleration level.

I would disagree. Certainly the 1st generation of rotating space stations will likely be segmented, mainly because no one would feel confident in the design of such a large structure as a single volume as a first step. Assuming we're building mini-worlds in our first attempt leads to false assumptions.

Quote
I would add that there is another spinning geometry I developed for the 2016 NASA space apps challenge - the "spiral space station" twin spiral framework geometry - which I like as a model for space habitats around asteroids, because it can feasibly keep growing/renewing itself as long as resources are available.

Interesting framework system, but did you simulate what the stresses would be when fully built out? Sure seems like this type of design relies on the principle of the "weakest link", where if one link fails the whole thing could unzip. Also I'm not sure how this improves on the issue you listed above of having a single volume, since this spiral design is essentially one long tube with no cross connections.

Nevertheless it is a clever design that could end up providing some hints to how low-weight stations could be built.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Online mikelepage

I don't particularly like them because they tend to use single large volume pressure vessels, which must be built in their entirety before they can even start being useful.  Making them small enough to be feasible requires the occupants to tolerate higher spin rates for a given launch mass/acceleration level.

I would disagree. Certainly the 1st generation of rotating space stations will likely be segmented, mainly because no one would feel confident in the design of such a large structure as a single volume as a first step. Assuming we're building mini-worlds in our first attempt leads to false assumptions.
Not quite sure what you're disagreeing with, but I should have clarified that I meant I don't like them for their feasibility in the near future (i.e. before 2100) not because I don't think they can work.

Quote
Quote
I would add that there is another spinning geometry I developed for the 2016 NASA space apps challenge - the "spiral space station" twin spiral framework geometry - which I like as a model for space habitats around asteroids, because it can feasibly keep growing/renewing itself as long as resources are available.

Interesting framework system, but did you simulate what the stresses would be when fully built out? Sure seems like this type of design relies on the principle of the "weakest link", where if one link fails the whole thing could unzip. Also I'm not sure how this improves on the issue you listed above of having a single volume, since this spiral design is essentially one long tube with no cross connections.

Nevertheless it is a clever design that could end up providing some hints to how low-weight stations could be built.

No, we didn't do/haven't done any stress simulations (it was a 48 hour hackathon), but I would be interested to do them, because that would probably guide how many layers deep the structure needs to be, and how soon the inner (older) sections of the spiral could be removed and recycled.  I can't intuitively visualise where the "weakest link" would be, because it seems to me all tensile stresses are spread evenly and you'd have to have multiple layers break above and below the same point in order for the whole structure to fail.  It was referencing a nautilus shell, which contains a single spiral of pressure chambers, each bigger than the last, so I'd imagine that biomimicry would be further referenced in a more complete design.

You might have noticed we were hedging on whether it would be a dual archimedes spiral (where the radial cross section of each frame element remains constant, even as the length of each arc-segment increases), or whether it would be a dual log spiral (where every single frame element is scaled up by some % fraction on the last one).  That would probably depend on whether the frame elements were being prefabbed, or 3D printed/fabricated in place.

Thanks for the complements.  The thing I really like about it is that it is just a framework, so it need not be "one long tube" but could instead be a support structure for a series of inflatable pressure vessels, as big or small as needed, just as in a nautilus shell.  The nautilus shell is a log spiral btw, so if a spiral space station continued to be built out ad infinitum, you could eventually see huge internal spaces existing as part of that.  Even then, there would be safety in being able to move to adjacent pressure chambers both radially, and tangentially.  If the worst did happen and a pressure vessel was lost, the whole structure wouldn't unzip, but you'd just have to replace the "dead" chamber.

Tags: