Artificial Gravity Testbeds

[Coastal Ron]

..However VR is not really related to the topic of artificial gravity, since VR can also be used in zero gravity situations, and VR does not really mitigate the negative physical effects of reduced or zero gravity.

I suspect I drowned my point in my enthusiasm. I edited my post down to make sure I was only responding to how an AR treadmill would be applied to the problem of this thread, which I understand to be primarily about answering human unknowns like gravity needed for bone mass, tolerance to small radii etc.

I think Im on to something. The volume of a Dragon 2 is enough. You could do it in two F9R launches, and only a single launch for following missions.

Ah, OK, my bad. Not sure if we know how long an experiment needs to run before we find out the effects of artificial gravity, but this idea does have the appeal of using a great deal of existing hardware and capabilities.

Perhaps the next step is to see if there are any estimates for how long artificial gravity experiments would need to run for humans, or how long they would need to run for smaller animals (supervised by humans)?

[Paul451]

1) Given how trivial propellant cost is for spin-up, I doubt the cost of developing a flywheel-based system is worthwhile.

2) Dragon-crew trunk can hold cargo. Total cargo-mass to LEO is given as 6 tonnes, split between capsule and trunk, and approx. 3 tonnes to ISS. The maximum amount in the trunk isn't given, but for that smaller ISS payload, the ratio is 3:1 with the trunk carrying up to 800kg. If the ratio holds, then you can carry around 1.5 tonnes in the trunk, which might be enough for the tether system. You could potentially get away with a single launch architecture, depending on the RPM vs g-load range you are interesting in. (If the trunk cargo is hard-limited at 800kg, then probably the only way to fit it into a single launch would be to use the F9 upper-stage as a tether counter-mass, so the 800kg is just the tether mechanism. But that limits you to a two-end tether, not a triangular arrangement.)

3) I see no reason why you couldn't fit treadmills inside the capsule. Even a conventional full length treadmill. Once the seats are folded away, the capsule seems fairly roomy -- 3m to 2m tapering across the width, 2.3m height. You could easily fit a pair of those VR "treadmills" for simultaneous use. No need to take turns.

But...

What is the intended point of adding VR? It seems like you are adding a whole extra set of motion-sickness variables to a study on motion sickness/adaptation under AG. If it's just to add exercise, any treadmill will do. If it's to study movement under AG, static motion (bending, reaching, coordination tests, etc) will be more definitive.

If you are trying to test non-static "moving around" (like walking/running) under AG, the VR/treadmill combo won't provide you with useful data. You aren't actually moving around, therefore your rotational velocity isn't changing (let alone differently based on direction), hence you aren't actually experiencing/testing any additional Coriolis effects, compared to static testing.

Unless it's just a boredom/claustrophobia counter-measure, then I don't see the purpose. (As an anti-boredom measure, to allow a longer missions in a small capsule without cabin-fever, it seems very useful. And fun.)

[KelvinZero]

Not sure if we know how long an experiment needs to run before we find out the effects of artificial gravity..

Final point.. you could also plug larger hab modules into the exact same design. If the Dragon version could handle 1g you would not even need to make it redundantly large for a much larger dedicated hab to test mars gravity.

Im enthused about this spin-up, spin-down module. I hope I get a chance to mess around with a mock up in blender.

...

1) Yeah you are probably right. Also, I think we can think of the flywheel as an optional module, since it would work without being at the center of mass. I don't mean a module we would physically attach and detach, but as a part of the design that can be easily interchanged with others in the "spitballing" part of design.

One big advantage I thought it might have though: Would it reduce or eliminate those instability issues because the entire thing has zero angular momentum?

2) Sounds good. Could be doable.

3)Well the main point of that link was the 2d treadmill, which would test all sorts of things except the varying gravity from moving in the direction of spin etc.

The VR part is only a tiny addition of mass. I think the body tracking, the eye tracking, the ability to modify levels to encourage certain activities (like turning right/left, ducking as shown in that link, pressing buttons in 3d), and also to compare with the exact same experiment on earth, would be very useful for gathering information... And yeah, it might also help with boredom if two people were to live in a dragon sized capsule for long durations... all that for including a pair of goggles and a game console.

I did think that maybe a projected panorama might be better for avoiding eyestrain, with or without 3d specs. I dont know if that exists.

[MickQ]

..However VR is not really related to the topic of artificial gravity, since VR can also be used in zero gravity situations, and VR does not really mitigate the negative physical effects of reduced or zero gravity.

I suspect I drowned my point in my enthusiasm. I edited my post down to make sure I was only responding to how an AR treadmill would be applied to the problem of this thread, which I understand to be primarily about answering human unknowns like gravity needed for bone mass, tolerance to small radii etc.

I think Im on to something. The volume of a Dragon 2 is enough. You could do it in two F9R launches, and only a single launch for following missions.

Ah, OK, my bad. Not sure if we know how long an experiment needs to run before we find out the effects of artificial gravity, but this idea does have the appeal of using a great deal of existing hardware and capabilities.

Perhaps the next step is to see if there are any estimates for how long artificial gravity experiments would need to run for humans, or how long they would need to run for smaller animals (supervised by humans)?

Years of data from ISS should help in determining test lengths just by showing the average time spent in zero G when deterioration starts.  This should indicate the minimum length, at least, for any AG experiment. 

[Coastal Ron]

Not sure if we know how long an experiment needs to run before we find out the effects of artificial gravity..

Final point.. you could also plug larger hab modules into the exact same design. If the Dragon version could handle 1g you would not even need to make it redundantly large for a much larger dedicated hab to test mars gravity.

Just to be clear though, you wouldn't do this experiment to test for 1G, because we already know that humans can survive in 1G. I would hope that you would test for Mars level gravity, since to me that could be the "low gravity standard" for artificial gravity stations since Mars will become the "other" major gravity level that humans adapt to (we hope!).

[Paul451]

Just to be clear though, you wouldn't do this experiment to test for 1G, because we already know that humans can survive in 1G.

You test at 1g to separate out specific effects of spin from effects of varying gravity. [Also effects of the spacecraft that differ from ground tests. Noise/vibration/air-quality/etc.] If your AG system produces results at 1g that match Earth controls, you have more confidence that Mars-g and Lunar-g tests are showing actual Mars/Moon-equivalent results.

Or, flipping it around, suppose you get a result suggesting that people still suffer health issues even at Mars-g, simply because there's an AG effect that wasn't successfully controlled for. Even moreso, animal studies that suggest reproductive issues. You would be creating a false believe that humans can't tolerate permanent lunar or even Mars settlement.

That said, I don't think Dragon would produce useful results for human health. The time-on-orbit (even assuming extra work is done by SpaceX to extend it) is just too short. You could expand the tiny sample size by including animals, but the time-on-orbit is still being to be limited to a few weeks at most.

[KelvinZero]

That said, I don't think Dragon would produce useful results for human health. The time-on-orbit (even assuming extra work is done by SpaceX to extend it) is just too short. You could expand the tiny sample size by including animals, but the time-on-orbit is still being to be limited to a few weeks at most.

That probably just applies to the single launch scheme.
Wikipedia claims https://en.wikipedia.org/wiki/Crew_Dragon_Endeavour stayed in orbit attached to ISS for 200 days. For the two launch scheme the dragon would also be docked to something else, the counterweight module, which could supply the lifesupport somehow. All that weight has to be good for something, though I had imagined just solar power and batteries.

..or it could just be a preliminary mission before attaching a full hab.

Is there a near or existing hab module we could use as a target? What do you guys feel is enough?

[Paul451]

Wikipedia claims https://en.wikipedia.org/wiki/Crew_Dragon_Endeavour stayed in orbit attached to ISS for 200 days.

That's on standby/dormant. Not in use. They seem to be limited to 7 days or so when in use. I suspect you could extend that, thanks to having just two people. But not by much. That's why I think the only thing you'd be testing is your mechanical/balance assumptions about living in AG, not long term health effects vs 0g. Not worthless, but it'd have to be cheap to justify itself.

For the two launch scheme the dragon would also be docked to something else, the counterweight module, which could supply the lifesupport somehow.
[...]
..or it could just be a preliminary mission before attaching a full hab.

I suspect that the necessary additions to allow Dragon to remain on-orbit for long periods without being docked to a station would effectively be a full hab (single module station). All Dragon is providing is the pressure vessel, which is not the difficult part. So the engineering might be easier if you just bite the bullet and add a dedicated hab.

Essentially, you are adding parts until you reinvent VAST.

[KelvinZero]

I suspect that the necessary additions to allow Dragon to remain on-orbit for long periods without being docked to a station would effectively be a full hab (single module station). All Dragon is providing is the pressure vessel, which is not the difficult part. So the engineering might be easier if you just bite the bullet and add a dedicated hab.

Essentially, you are adding parts until you reinvent VAST.

Ah yeah, you are probably right. Is there a near or existing hab module we could set as the goal? How much space do we need? Eg can we specify one of the options from these two companies as sufficient?

https://www.vastspace.com/
(I notice it mentioned lunar gravity experiments on that page.. also 30 days with 4 astronauts)

https://www.sierraspace.com/commercial-space-stations/life-space-habitat/
(I like the idea of inflatable because size is directly relevant to the experiment)

And perhaps we could use the F9R fairing to constrain the size of parts we can launch?

Sounds like three components: the hab, whatever counterweight solution, the dragon to deliver the crew and some more supplies.
So three launches, or two if the hab and counterweight can fit in one F9R fairing.

A final requirement could be sufficient lifesupport for sufficient crew (im assuming 2 is enough). What should we specify as sufficient duration? An off the shelf solution may not exist but we could specify what volume and mass we can assume it adds to the mission?

[Paul451]

I think my preference would be to assume that the longer-term AG research is being looked at by groups like VAST, or require a much larger AG station.

In which case, focus on a life-support/etc engineering testbed, not a human health research station. Essentially, you're testing what 1g equipment/systems can work with little or no adaptation to partial-g (and down to what level.) If it's productive, later flights could test more heavily modified systems, or give the confidence to test more off-the-shelf 1g systems, depending on the early results.

Your proposed two-launch (or a one-launch using the F9US as the counterweight) minimalist set up would provide an environment to test life-support, water-recyc, toilet design(s), even bathing & exercise equipment, under less-than-1g-but-more-than-0g conditions.

There might be some animal candidates that produce very quick effects under 0g, which could also be flown on such flights. (In which case, JAXA might chip in on such flights. At least in building the animal habs.)

Flight time would be 7 days per mission, varying spin-rates and g-levels each day. With a stretch-goal of two weeks if SpaceX is willing/able to do whatever tweaks are required and/or if the partial-g life-support systems being tested actually work. As a side-effect, you are going to get feedback from your two crew about any weird mobility/balance/nausea effects of living in AG that contradict ground studies. (Since they'll have done pre-launch adaptation training, they'll have a good sense of the differences.)

[Coastal Ron]

A story relevant to the testing artificial gravity testbeds could do:

Kidneys in space: Why a trip to Mars could end in dialysis - New Atlas

Relevant quote:

A lengthy trip to Mars, which exposes astronauts to a combination of cosmic radiation and weightlessness, could result in permanent kidney damage, according to a new study. It's the largest analysis to date on how spaceflight affects kidney health.

There are already NSF threads that deal with transit time to Mars, so lets stay focused on what artificial gravity testbeds could do to help answer the question of whether artificial gravity can mitigate some (or all) of the deleterious effects of space on human kidneys.

For instance, as a business case for building an artificial gravity testbed (i.e. some form of small or inexpensive rotating space station), is medical research for future space and Mars inhabitants enough "demand" to merit building such a testbed?

One of the reasons I have seen for testbeds is for figuring out if Mars level gravity is enough to mitigate health issues, not only for future Mars colonists, but also for future rotating space stations that are built for Mars gravity instead of Earth gravity - Mars gravity is less expensive to create than Earth gravity, so it would be nice to know humans can survive in Mars gravity.

And while artificial gravity testbeds won't necessarily be related to the transportation systems for moving humans to Mars, the science could overlap.

But the big question continues to be, who would pay for such research?

[StraumliBlight]

This webinar was kinda interesting:

-Steve Hoeser (Moderator) - Senior Technical Advisor, Beyond Earth Institute
-Donna Roberts, MD, MS - Deputy Chief Scientist, ISS National Lab
-Dr. Dana Levin - Chief of Space Medicine, Vast Space
-Gary Hudson - President, Space Studies Institute
-Dr. Ted Hall - Extended Reality Software Developer, University of Michigan

[Coastal Ron]

This webinar was kinda interesting:

-Steve Hoeser (Moderator) - Senior Technical Advisor, Beyond Earth Institute
-Donna Roberts, MD, MS - Deputy Chief Scientist, ISS National Lab
-Dr. Dana Levin - Chief of Space Medicine, Vast Space
-Gary Hudson - President, Space Studies Institute
-Dr. Ted Hall - Extended Reality Software Developer, University of Michigan

Did you watch it? If so, please provide a summary so everyone can know if it is worth watching... 

[mikelepage]

But the big question continues to be, who would pay for such research?

As much as I would like to avoid the “space as a playground for the rich” narrative, I’m starting to think the fiscal realities of NASA and other government space programs make it the most likely answer. Answering scientific questions then becomes a nice add-on, but the primary goal would be adventure tourism/fun. Think finely-clothed celebrities and CEOs sitting down to a chef-cooked dinner <cue close-up shot of red wine swirling in a glass at Mars-G> before sitting down for a private Ed Sheeran concert for 30 people. And anything else that leans into the fact that it’s an exclusive experience.

In this light, the argument for building AG space stations can take on a somewhat different emphasis. What do rich people most lack? Time. What does training for a space mission currently require? 3-6 months of training. What will AG save the most? Time, both in training for, and then adapting to, space flight. 

[Paul451]

adventure tourism/fun. Think finely-clothed celebrities and CEOs sitting down to a chef-cooked dinner <cue close-up shot of red wine swirling in a glass at Mars-G> before sitting down for a private Ed Sheeran concert for 30 people.

That's not "adventure tourism" as it's usually meant. It's usually intended to mimic the idea of being an "explorer" or "pioneer", not to just be yet-another-luxury-resort. Especially high-value adventure tourism; around-the-"world" yacht races, mountain-climbing, crossing the pole(s), etc etc.

[lamontagne]

I think Tim Urban in wait but Wait but Why column said it well almost eight year ago:  the intersection between those who want to go and those who can afford the cost.

https://waitbutwhy.com/2015/08/how-and-why-spacex-will-colonize-mars.html/3

This will be true for gravity testbeds as for Mars.

[mikelepage]

adventure tourism/fun. Think finely-clothed celebrities and CEOs sitting down to a chef-cooked dinner <cue close-up shot of red wine swirling in a glass at Mars-G> before sitting down for a private Ed Sheeran concert for 30 people.

That's not "adventure tourism" as it's usually meant. It's usually intended to mimic the idea of being an "explorer" or "pioneer", not to just be yet-another-luxury-resort. Especially high-value adventure tourism; around-the-"world" yacht races, mountain-climbing, crossing the pole(s), etc etc.

Agreed, but I’m not sure there’s a separate name for what I mean. One difference between ascending Everest, and James Cameron going to the bottom of the Marinara trench is that - I don’t think - Cameron had to do any physical endurance training to operate the sub. Presumably you don’t actually have to be near the limits of human capacity for it to count as an adventure.

I think the other confounding factor is that almost all the places that remain unexplored these days are so because they tend to be pretty inhospitable places. If there was a module containing a luxury restaurant at the top of Everest, or the bottom of the sea, it would still be adventure tourism if getting there was still an adventure. I’m thinking a bit here of  https://www.hurawalhi.com/dining/undersea-restaurant/

Is “luxury adventure tourism” a category? Retrace the great explorations of history, but with good food, hot showers and great entertainment to while away the boring parts Going to space would be the adventure part, and staying at the partial AG space station would be the luxury/exclusive/fun part.

[Coastal Ron]

adventure tourism/fun. Think finely-clothed celebrities and CEOs sitting down to a chef-cooked dinner <cue close-up shot of red wine swirling in a glass at Mars-G> before sitting down for a private Ed Sheeran concert for 30 people.

That's not "adventure tourism" as it's usually meant. It's usually intended to mimic the idea of being an "explorer" or "pioneer", not to just be yet-another-luxury-resort. Especially high-value adventure tourism; around-the-"world" yacht races, mountain-climbing, crossing the pole(s), etc etc.

Agreed, but I’m not sure there’s a separate name for what I mean. One difference between ascending Everest, and James Cameron going to the bottom of the Marinara trench is that - I don’t think - Cameron had to do any physical endurance training to operate the sub. Presumably you don’t actually have to be near the limits of human capacity for it to count as an adventure.

I think that is an important distinction.

I think the other confounding factor is that almost all the places that remain unexplored these days are so because they tend to be pretty inhospitable places. If there was a module containing a luxury restaurant at the top of Everest, or the bottom of the sea, it would still be adventure tourism if getting there was still an adventure.

Is “luxury adventure tourism” a category? Retrace the great explorations of history, but with good food, hot showers and great entertainment to while away the boring parts Going to space would be the adventure part, and staying at the partial AG space station would be the luxury/exclusive/fun part.

Like many definitions, "adventure tourism", or "adventure travel", is kind of a squishy concept, but Wikipedia defines "adventure travel" as:

Adventure travel is a type of tourism, involving exploration or travel with a certain degree of risk (real or perceived), and which may require special skills and physical exertion.

Travel to space today, and in the near-term, would definitely require assuming some degree of real risk, not only from the transportation portion of the trip, but also because space can kill you in many ways.

As to your point about who does adventure travel, it is not the poor, and likely not the broad "middle class". You need to have disposable income and abundant time, so this type of activity is more likely to be people with some degree of both money and time.

So for artificial gravity testbeds, maybe a business model is being a destination along with being a medical testbed? Can't say that living on a rotating small station would be anything close to luxury, but maybe the experience could be combined with a chance of going to Mars?

[Twark_Main]

I think Tim Urban in wait but Wait but Why column said it well almost eight year ago:  the intersection between those who want to go and those who can afford the cost.

https://waitbutwhy.com/2015/08/how-and-why-spacex-will-colonize-mars.html/3

This will be true for gravity testbeds as for Mars.

Note that Tim Urban (by his own admission) only "said it well" because he was just lifting phrases and concepts that Elon Musk had been saying for years at that point. 

https://waitbutwhy.com/2015/12/spacex-launch-live-webcast-and-explanation-1-21-15.html

[mikelepage]

Cross posting here because it's getting off topic for the original thread:

The reason I don't like the punctuated gravity idea is that it presumes that biomedical problems are the only ones we're solving with spin G.

Constant (or near-constant) spin G of some sort will save money by removing the necessity to redesign for microgravity, every machine or process which deals with any kind of fluid. The initial upfront investment is dwarfed by the ongoing development costs of not doing it. Plus, non-medical human factors issues are going to be the long pole in getting the general public to actually *want* to settle space.

The caveat there is that the rotation or spin system then becomes a critical system element. If the structure has to be spun down or rotation stopped, then those acceleration-dependant systems either need a microgravity-operation fallback mode (that incurs the costs you are trying to avoid), or a redundant microgravity backup system to be carried anyway.

Agree with the bolded, but I don't think your conclusions follow. It's unlikely any spin system would exist in isolation from visiting spacecraft, and these would possess microgravity-optimised systems as usual. For clarity, I should say my preferred model of operations involves regular rendezvous of a spinning space station with visiting vehicles for crew-rotations - involving a spin down of the system to microgravity for little more than the duration of the visit. As I suggested upthread, it would be the visiting vehicles doing the spinning up and down, so crews would always have access to a spacecraft with systems optimised for zero G (these also function as emergency escape vessels).

This way, most equipment on the spin station could be derived largely from aircraft/cruise ship/mobile home-developed counterparts and would need only minor design tweaks so as not to break during micro- and hyper- gravity phases of flight. Much more scalable.