Author Topic: Non-HSF, near-term spin gravity experiments  (Read 18101 times)

Offline mikelepage

This is the second spin off (I blame KelvinZero for the bad pun :D ) of the "Realistic, near-term Rotating Space station" thread.

This is to focus on animal models and engineering demonstrations.  The idea is that this is for proposals, the results of which will inform HSF spin gravity, but because of the lower risk/lower cost associated with non-HSF missions, this can be more experimental.

The advantage of limiting test subjects to smaller animals is that the limiting factor of spin gravity is not, technically, the spin rate (in rpm), but the differential acceleration of the subjects inside.  i.e. the ratio of the animal size to the radius length of the spin.  A rat in a spin gravity environment with r=5m is equivalent to human in a spin gravity environment with r=45m.

So one consequence of this is that current launch vehicles are capable of launching torus-type habitats of suitable size for animal subjects, but not for humans.



Another possible application in the non-HSF space is as test articles for space-based, vacuum capable 3D printer such as that developed by Made In Space:



What do you think?
« Last Edit: 01/19/2016 03:42 AM by mikelepage »

Offline Coastal Ron

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Re: Non-HSF, near-term spin gravity experiments
« Reply #1 on: 01/19/2016 03:50 AM »
Nice move, since the HSF version of this thread was having challenges coming up with testable versions that wouldn't break the bank (my suggestions included).

I'll give this some thought and come back...
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline mikelepage

Re: Non-HSF, near-term spin gravity experiments
« Reply #2 on: 01/19/2016 08:19 AM »
Bringing these two across from the HSF AG thread:

A lot of the questions early on could be answered cheaply with a bio satellite carrying a much smaller mammal such as mice.
This could be one of the first missions for Dragon lab.
https://en.wikipedia.org/wiki/Mars_Gravity_Biosatellite

Interesting that Elon Musk was involved in that circa 2001.

the only way this gets settled is when some billionaire decides to start a company to do this

It's kinda hard to imagine that Elon Musk doesn't know the problem exists.. maybe MCT will involve a low-g experiment or two before they set off to conquer Mars.


I asked Elon to support the SSI G-lab proposal in 2012 by contributing an FH flight.  He told me it was not a priority for him.

I believe it will take about ten years after the lab comes on-line to get a definitive answer to the questions that need to be addressed.  You need at least a couple of generations of animals to live and die in reduced G.

My immediate response to that is: he doesn't wanna know the answer. Say all your experiments tell you that Mars gravity is no good and all mammals born on Mars will fail to reach maturity. Colonization of Mars clearly couldn't go ahead until these problems are solved. I would imagine Elon would make the argument that figuring out these problems is best done on Mars at something like a McMurdo Station, but is this much reduced vision really inspiring enough? Do we want to know the answer? We might never get over a shock like that.

As a scientist, I prefer knowledge over ignorance, but I also believe we can overcome any obstacle.

Yeah, I wasn't actually thinking of Musk in this case.  He will be more than happy to sell flights to anyone who wants to work on it I think, but I don't think he sees that as a high priority problem to solve.

I am personally dubious that people will ever live long-term in low-g environments (less than say 80% of 1xg) because the amount of adaptation required (at least, any time in the near future).  Correspondingly I think it's much more important to develop the principles of building large scale rotating space stations.

One thing I'd like to quiz people on, is how you might design a system in the context of spin gravity that regulates temperature passively.  Where as temperature rises, the craft automatically uncovers more radiators, or alternatively, presents less surface area to the sun.  Can you use a gyroscopic motor and Coriolis forces to drive the flow of radiator fluid around the craft? 

It would be cool if eventually, the current generation ECLSS systems became like parachutes on the propulsively landing Dragon v2... for use in the case of an emergency.

Offline mikelepage

Re: Non-HSF, near-term spin gravity experiments
« Reply #3 on: 01/20/2016 09:09 AM »
You need at least a couple of generations of animals to live and die in reduced G.

That seems to be the crucial divide. Some people don't seem to see the importance of that.

Of course there's a great overview of this stuff from a recent Space Access presentation. Probably everyone interested in this thread (other than those who were in the room at the time) should take a few minutes to watch it.



This video was posted in the human space flight thread, and is also relevant to this one:

The basic concept is to have an artificial gravity research facility launched by Falcon Heavy, and maintained in an identical orbit to the ISS, but trailing it by some safe number of kilometers, such that ISS astronauts would be able to service it by boarding a transfer craft and travelling to it for the cost of some trivial amount of propellant.

Interesting that the speaker Gary Hudson also considers the animal work to be the most crucial outcome (specifically vertebrate work - because that will be most relevant to human skeletons) and is only considering making it human rated because of the difficulty of telerobotically performing the various tasks associated with an animal research facility.

I think such an animal facility could be made autonomous if it was a multi-species habitat that had full nitrogen/oxygen/water cycles a la biosphere and biosphere 2.  If it was put into the same orbit as the ISS (or other commercial space station) that would make adding or retreiving various experiment pods much easier.

Offline HMXHMX

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Re: Non-HSF, near-term spin gravity experiments
« Reply #4 on: 01/20/2016 05:56 PM »
You need at least a couple of generations of animals to live and die in reduced G.

That seems to be the crucial divide. Some people don't seem to see the importance of that.

Of course there's a great overview of this stuff from a recent Space Access presentation. Probably everyone interested in this thread (other than those who were in the room at the time) should take a few minutes to watch it.

...

Since I first proposed the G-Lab in 2012, my intent has always been to locate it in co-orbit with ISS to take advantage of frequent ISS resupply and crew flights to reduce access cost, plus provide an on orbit safe haven for both facilities.
This video was posted in the human space flight thread, and is also relevant to this one:

The basic concept is to have an artificial gravity research facility launched by Falcon Heavy, and maintained in an identical orbit to the ISS, but trailing it by some safe number of kilometers, such that ISS astronauts would be able to service it by boarding a transfer craft and travelling to it for the cost of some trivial amount of propellant.

Interesting that the speaker Gary Hudson also considers the animal work to be the most crucial outcome (specifically vertebrate work - because that will be most relevant to human skeletons) and is only considering making it human rated because of the difficulty of telerobotically performing the various tasks associated with an animal research facility.

I think such an animal facility could be made autonomous if it was a multi-species habitat that had full nitrogen/oxygen/water cycles a la biosphere and biosphere 2.  If it was put into the same orbit as the ISS (or other commercial space station) that would make adding or retreiving various experiment pods much easier.

Offline Paul451

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Re: Non-HSF, near-term spin gravity experiments
« Reply #5 on: 01/22/2016 11:42 AM »
I think such an animal facility could be made autonomous if it was a multi-species habitat that had full nitrogen/oxygen/water cycles a la biosphere and biosphere 2.

It's not just lifesupport duration, but maintenance of systems and especially cleaning of animal cages. If you want multi-generation run-times, then you need to deal with dead animals at each stage in their life-cycle. Along with clogged feed-tubes, algae blocked water pipes, etc. Animal labs seem to be pretty high-maintenance.

Gary Hudson's aside about man-tended facilities makes me wonder how long an autonomous facility could run. I was thinking sub-lifecycle ranges for early experiments (1-3 months, with a stretch goal of a year in later missions) when proposing a spinning DragonLab mission as the simplest/cheapest I could think of. But I wonder, even for that, how unhealthy the animals would be from the lab set-up alone.

[For the sake of the thread:
I suggested a DragonLab (science variant of SpaceX's Dragon capsule) being spun around it's long axis. Animal habs in a ring around the rim of the capsule, ECLSS and support systems down the centre of the capsule. Additional power and support via the trunk. Unmanned (obviously), but with the capability of returning the samples to Earth for analysis at the end-of-mission. Different runs could use different spin-rates, hence different g-loads. And stacked animal habs could provide different g-loads at the same RPM, eg, at 15RPM, cages at 1.5m radius are at Mars 'g', cages at 0.65m radius at at lunar 'g'.]

Offline RonM

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Re: Non-HSF, near-term spin gravity experiments
« Reply #6 on: 01/22/2016 01:33 PM »
I think such an animal facility could be made autonomous if it was a multi-species habitat that had full nitrogen/oxygen/water cycles a la biosphere and biosphere 2.

It's not just lifesupport duration, but maintenance of systems and especially cleaning of animal cages. If you want multi-generation run-times, then you need to deal with dead animals at each stage in their life-cycle. Along with clogged feed-tubes, algae blocked water pipes, etc. Animal labs seem to be pretty high-maintenance.

Gary Hudson's aside about man-tended facilities makes me wonder how long an autonomous facility could run. I was thinking sub-lifecycle ranges for early experiments (1-3 months, with a stretch goal of a year in later missions) when proposing a spinning DragonLab mission as the simplest/cheapest I could think of. But I wonder, even for that, how unhealthy the animals would be from the lab set-up alone.

[For the sake of the thread:
I suggested a DragonLab (science variant of SpaceX's Dragon capsule) being spun around it's long axis. Animal habs in a ring around the rim of the capsule, ECLSS and support systems down the centre of the capsule. Additional power and support via the trunk. Unmanned (obviously), but with the capability of returning the samples to Earth for analysis at the end-of-mission. Different runs could use different spin-rates, hence different g-loads. And stacked animal habs could provide different g-loads at the same RPM, eg, at 15RPM, cages at 1.5m radius are at Mars 'g', cages at 0.65m radius at at lunar 'g'.]

Yes, small mammal cages would be high maintenance. Without proper care, unhealthy animals could skew the results.

A multigeneration man-tended lab would be the best for long term study, but a short duration experiment using a Dragon Lab could tell us a lot. For example, if mice showed bone loss at lunar gravity, but not at Mars gravity, that would be a significant find. The high RPM might be a problem, but we won't know if we don't try.

Offline Vultur

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Re: Non-HSF, near-term spin gravity experiments
« Reply #7 on: 01/24/2016 08:43 PM »
Bringing these two across from the HSF AG thread:

A lot of the questions early on could be answered cheaply with a bio satellite carrying a much smaller mammal such as mice.
This could be one of the first missions for Dragon lab.
https://en.wikipedia.org/wiki/Mars_Gravity_Biosatellite

Interesting that Elon Musk was involved in that circa 2001.

the only way this gets settled is when some billionaire decides to start a company to do this

It's kinda hard to imagine that Elon Musk doesn't know the problem exists.. maybe MCT will involve a low-g experiment or two before they set off to conquer Mars.


I asked Elon to support the SSI G-lab proposal in 2012 by contributing an FH flight.  He told me it was not a priority for him.

I believe it will take about ten years after the lab comes on-line to get a definitive answer to the questions that need to be addressed.  You need at least a couple of generations of animals to live and die in reduced G.

My immediate response to that is: he doesn't wanna know the answer. Say all your experiments tell you that Mars gravity is no good and all mammals born on Mars will fail to reach maturity. Colonization of Mars clearly couldn't go ahead until these problems are solved. I would imagine Elon would make the argument that figuring out these problems is best done on Mars at something like a McMurdo Station, but is this much reduced vision really inspiring enough? Do we want to know the answer? We might never get over a shock like that.

As a scientist, I prefer knowledge over ignorance, but I also believe we can overcome any obstacle.

Yeah, I wasn't actually thinking of Musk in this case.  He will be more than happy to sell flights to anyone who wants to work on it I think, but I don't think he sees that as a high priority problem to solve.

I am personally dubious that people will ever live long-term in low-g environments (less than say 80% of 1xg) because the amount of adaptation required (at least, any time in the near future).  Correspondingly I think it's much more important to develop the principles of building large scale rotating space stations.

One thing I'd like to quiz people on, is how you might design a system in the context of spin gravity that regulates temperature passively.  Where as temperature rises, the craft automatically uncovers more radiators, or alternatively, presents less surface area to the sun.  Can you use a gyroscopic motor and Coriolis forces to drive the flow of radiator fluid around the craft? 

It would be cool if eventually, the current generation ECLSS systems became like parachutes on the propulsively landing Dragon v2... for use in the case of an emergency.

Or maybe Musk is confident that it won't be a real problem for colonization of Mars.

(As am I. Fluid should distribute fine at 38% g, and bone strength is only relevant if you are going to come back to earth, which is not a requirement for colonization.)

Offline mikelepage

Re: Non-HSF, near-term spin gravity experiments
« Reply #8 on: 01/25/2016 03:34 AM »
Or maybe Musk is confident that it won't be a real problem for colonization of Mars.

(As am I. Fluid should distribute fine at 38% g, and bone strength is only relevant if you are going to come back to earth, which is not a requirement for colonization.)

We just don't know, that's the problem.

There are a lot of ways bone strength could be a problem even on mars.  Or more generally, the differentials between bone strength, ligament strength, muscle strength, blood vessel wall strength, abdominal wall membrane strength (or any kind of membrane strength), as well as potential issues with pressure regulation present in gastrointestinal tract systems/ urinary tract systems - as well as endolymphatic/endocrinology systems (plausible but also kinda sucks if we find out all men have erectile dysfunction after extended duration on mars/below 1xg  - there is some real science to be done on sex in space lol).  Long story short: Lots of mutations/hundreds or more generations required before mammals/vertebrates can become fully adapted to life on mars. 

Elon Musk is a great thinker of our time, spectacular engineer and physicist, but a number of things he's said makes me think he hasn't really studied biomedical science to any great degree.  For obvious reasons, rocket scientists are the predominant scientists in the space industry today, but as colonisation of space gets underway, this is where all kinds of medical/biological science will come to the fore.

It may well be that humans become like ocean dwelling salmon that need to return upstream to spawn.  Perhaps for a long time, humans will need to return to Earth or to ~1xg in order to have children.  It's very plausible in my mind that we might be able to manage all the other effects of <1xg but pregnancy has a very specific set of requirements.

Offline Paul451

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Re: Non-HSF, near-term spin gravity experiments
« Reply #9 on: 01/25/2016 09:28 PM »
We just don't know, that's the problem.
There are a lot of ways bone strength could be a problem even on mars.  [...] Long story short: Lots of mutations/hundreds or more generations required before mammals/vertebrates can become fully adapted to life on mars.
Elon Musk is a great thinker of our time, spectacular engineer and physicist, but a number of things he's said makes me think he hasn't really studied biomedical science to any great degree.

Off-topic for your non-HFS thread, but there was a longer, quite rancorous thread (which I can't find now) specifically trying to speculate about what Musk might do if it turns out humans can't safely reproduce on Mars; hence ruling out colonisation.

(What I found interesting was how many people refused to accept the premise, and got quite angry when pushed, as if there was something inherently offensive about even considering it as a "what-if" case.)

Offline Vultur

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Re: Non-HSF, near-term spin gravity experiments
« Reply #10 on: 01/25/2016 11:23 PM »
We just don't know, that's the problem.
There are a lot of ways bone strength could be a problem even on mars.  [...] Long story short: Lots of mutations/hundreds or more generations required before mammals/vertebrates can become fully adapted to life on mars.
Elon Musk is a great thinker of our time, spectacular engineer and physicist, but a number of things he's said makes me think he hasn't really studied biomedical science to any great degree.

Off-topic for your non-HFS thread, but there was a longer, quite rancorous thread (which I can't find now) specifically trying to speculate about what Musk might do if it turns out humans can't safely reproduce on Mars; hence ruling out colonisation.

(What I found interesting was how many people refused to accept the premise, and got quite angry when pushed, as if there was something inherently offensive about even considering it as a "what-if" case.)

Well, I think it's something that kind of tends to degenerate into arguments by the nature of the case.

It's pretty much known from animal experiments that reproduction in even zero-g is possible, so it comes down to arguments about acceptable levels of safety.

Offline mikelepage

Re: Non-HSF, near-term spin gravity experiments
« Reply #11 on: 01/27/2016 02:58 AM »
The idea of having an experimental spin gravity setup co-orbital with ISS makes a lot of sense re servicing and retrieval of samples, but is also problematic what with synchronising re-boosts and dodging orbital debris etc.  Really, the main advantage is having the AG setup to be co-orbital with some human tended space station, and since I think we're probably talking 10 years before anything gets off the ground, that space station probably isn't ISS, but some Bigelow/other commercial station instead.

But what would be really handy is eliminating the requirement for humans to dock with the AG setup. 

Supposing each animal chamber was self-sufficient enough to last through many generations of the model organism it was hosting (big problem, but let's take that as given in this case), what you could have is a series of "sample retrieval" capsules that are launched attached to the habitat. 

After each time interval, one of these capsules would open a hatch into the main habitat.  The capsule is a trap.  The mice in the module all of a sudden smell cheese (for example) for the first time in months, and make their way inside the capsule.  Once the desired number of mice have entered the capsule, the hatch shuts and the capsule is launched: By simply detaching from the main habitat, the centripetal force drops it free into space, where it can be retrieved by a human piloted craft, and returned to Earth for analysis.

As long as the mice keep breeding, the numbers stay steady, and if the craft starts simulating 1xg and gradually ramps down, we can get a pretty good indication of what health problems crop up at various g levels, as well as how difficult it is to adjust back to 1xg on returning.

Offline Paul451

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Re: Non-HSF, near-term spin gravity experiments
« Reply #12 on: 01/27/2016 01:37 PM »
But what would be really handy is eliminating the requirement for humans to dock with the AG setup.

Yeah, I'm really curious what's the longest an independent system could run, without getting into complexity (and cost) like tele-operated robot arms, fully regenerative biological-based zero-maintenance life-support, etc. But I suspect animal research guys rarely hang out in spaceflight confs.

(First google result: http://www.ncbi.nlm.nih.gov/books/NBK54046. Even has a section on space volume. But nothing useful on automation.)

and since I think we're probably talking 10 years before anything gets off the ground

This is why I'd focus the smallest set-up possible. Even if it's not multi-generational, or not even a year. Just "whatever we can".

Supposing each animal chamber was self-sufficient enough to last through many generations of the model organism it was hosting (big problem, but let's take that as given in this case), what you could have is a series of "sample retrieval" capsules that are launched attached to the habitat. [...]

Alternatively, a nice bottle of LN2 to kill and freeze a certain number of the test animals after each interval. Once you freeze the last group, you can then do a single recovery of the freezer pod. You lose the "see how long it takes to re-adapt" part, but might be simpler than dozens (?) of individual return capsules.

Alternatively-alternatively, just use one sat per return. Smaller sample sizes, but more missions. That lets your crew build up their knowledge/experience on the hardware, and hopefully keeps your dev costs low by deferring some development to later missions. Ie, start with a month, low-g, incrementally work up to multi-year full-g as you "learn your craft".
« Last Edit: 01/27/2016 02:12 PM by Paul451 »

Offline RDoc

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Re: Non-HSF, near-term spin gravity experiments
« Reply #13 on: 01/28/2016 10:25 PM »
It's pretty much known from animal experiments that reproduction in even zero-g is possible, so it comes down to arguments about acceptable levels of safety.
Could you provide a link for some source material for that? I've not been able to find any experimental work on animal reproduction in zero g.

Offline Paul451

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Re: Non-HSF, near-term spin gravity experiments
« Reply #14 on: 01/29/2016 12:07 AM »
It's pretty much known from animal experiments that reproduction in even zero-g is possible, so it comes down to arguments about acceptable levels of safety.
Could you provide a link for some source material for that? I've not been able to find any experimental work on animal reproduction in zero g.

I believe Vultur is referring to embryo experiments on Earth using clinostats to simulate a kind of pseudo-weightlessness.

(Pop-sci article referencing research contradicting Vultur.)
« Last Edit: 01/29/2016 04:44 AM by Paul451 »

Offline Vultur

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Re: Non-HSF, near-term spin gravity experiments
« Reply #15 on: 01/29/2016 03:41 AM »
I believe Vultur is referring to embryo experiments on Earth using clinostats to simulate a kind of pseudo-weightlessness.

No... I've read about experiments in actual space. Will see if I can find the references.

Quote
(Pop-sci article referencing research contradicting Vultur.)

Not really - that article said that some worked out, but at lower rates. That agrees with my view that it is possible even in zero-g... but with higher chances of problems. Thus, if people wanted to live full-time in zero-g, it would come down to an ethical/safety argument about what level of increased risk is acceptable for adults to accept "for" their potential children. I mean, clearly it is a matter of degree - no one thinks it's unethical to live at high altitudes, though that definitely increases the chance of bad outcomes for pregnancy/birth.

But Mars g is a huge difference from zero g...

(Also, that was a complicated experiment - the rats didn't conceive naturally - which might also make it less successful.)

Offline punder

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Re: Non-HSF, near-term spin gravity experiments
« Reply #16 on: 01/29/2016 04:48 AM »
Or maybe Musk is confident that it won't be a real problem for colonization of Mars.

(As am I. Fluid should distribute fine at 38% g, and bone strength is only relevant if you are going to come back to earth, which is not a requirement for colonization.)

We just don't know, that's the problem.

There are a lot of ways bone strength could be a problem even on mars.  Or more generally, the differentials between bone strength, ligament strength, muscle strength, blood vessel wall strength, abdominal wall membrane strength (or any kind of membrane strength), as well as potential issues with pressure regulation present in gastrointestinal tract systems/ urinary tract systems - as well as endolymphatic/endocrinology systems (plausible but also kinda sucks if we find out all men have erectile dysfunction after extended duration on mars/below 1xg  - there is some real science to be done on sex in space lol).  Long story short: Lots of mutations/hundreds or more generations required before mammals/vertebrates can become fully adapted to life on mars. 

Elon Musk is a great thinker of our time, spectacular engineer and physicist, but a number of things he's said makes me think he hasn't really studied biomedical science to any great degree.  For obvious reasons, rocket scientists are the predominant scientists in the space industry today, but as colonisation of space gets underway, this is where all kinds of medical/biological science will come to the fore.

It may well be that humans become like ocean dwelling salmon that need to return upstream to spawn.  Perhaps for a long time, humans will need to return to Earth or to ~1xg in order to have children.  It's very plausible in my mind that we might be able to manage all the other effects of <1xg but pregnancy has a very specific set of requirements.

My humble opinion is that it will be much cheaper and safer to build a local centrifuge, rather than ship women and children back and forth between planets.

Offline Asteroza

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Re: Non-HSF, near-term spin gravity experiments
« Reply #17 on: 01/29/2016 06:41 AM »
Giant local ground centrifuge ring (which would be not that dissimilar to a rotating space station), or tilted circular track with a train doing loops? You could have an open air version of those hyperloop capsules using a hovercraft cushion on a sintered flat track, though unless you have a pantograph or pickup shoe to power it, you're going to need an RTG or something. Or the (night)train runs on batteries at night with passengers sleeping in bunks, and stops/recharges at a train platform during the day while dropping off people who work.

Though a train full of women and children trying to survive in a hostile environment starts to sound too close to the movie Snowpiecer...

Offline Paul451

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Re: Non-HSF, near-term spin gravity experiments
« Reply #18 on: 01/29/2016 06:57 AM »
Or the (night)train runs on batteries at night with passengers sleeping in bunks

Adding gravity during sleep is a waste. That's precisely when you don't benefit from it. (Remember, we use bed-rest to simulate reduced gravity.)

But the thread is non-HSF, there are at least two other live threads to talk about humans.

Offline mikelepage

Re: Non-HSF, near-term spin gravity experiments
« Reply #19 on: 01/30/2016 07:52 AM »
Moving this to here from the "cheapest HSF spin gravity thread" so I can answer on topic.

Look at it this way, what is the "control" for research on ISS? It's parallel work on Earth. The same will be true for the first AG experiments. It is much (much!) cheaper to replicate the non-g environmental factors on Earth, to look for confounding factors, than to do a 1g control experiment in space (and especially 1g at low-RPM.) It won't be enough, but it'll have to do.

It's the same with the sample size of the control group. What is an adequate control group size? Is it one guy in a Dragon capsule? Three in a BA-100? Of course not. But repeating enough runs to give you an adequate sample population for just the control-group would consume your entire budget, and an entire decade, preventing you from actually trying an actual data-run at lesser gravity. I'd much rather increase the number of runs, and hence sample size, at lower gravities - unless the initial few bracketing runs suspiciously all fail to find the transition zone.

A number of things that you've said are required to do the 1xg control (and therefore add expense) are not in my opinion necessary.  Animal work allows you to do higher RPM, and increase your sample numbers substantially.  Not sure if I misspoke/was vague earlier or why you zeroed in on the non-g environmental factors being cheaper to replicate and control for on Earth (assuming we can imagine all of them and replicate them), but it's the spin part of spin gravity which is what I'm saying is the essential control, since 1xg spin gravity may not be equivalent 1xg linear gravity biologically (i.e. force is equivalent, motion - macro or molecular - is not). 

There is also no need to include a separate control population of animals if you can retrieve animals as I wrote above.  You have a control time period when you spin the whole craft at 1xg and the entire animal population is subject to this.  You retrieve animals and return them to earth - compare to Earth-bound controls (which you also need to have).

Then you step the gravity/spin rate down over time.  I'm not quite sure how to design a craft that could house mice for years - but this would have to be shown as viable on Earth prior to launch.  For reference, mouse generation times are about 10 weeks (~5 generations in a year):

1) Launch and deploy, gaining valuable engineering validations.
2) Year one: Operate at 1 x g.  Acquire sample.
3) Year two: Operate at 0.9 x g.  Acquire sample (personally would be really interested in these results).
4) Year three: Operate at 2/3 x g. Acquire sample.
5) Year four: Operate at Mars g.  Acquire sample.
6) Year five: Operate at Lunar g.  Acquire sample.

Animal experiment.  Single Falcon 9 launch.  Yearly retrieval of samples by humans en route to or from co-orbital space station, without docking.  I find it very hard to believe this would not be in the same ballpark or less $$-wise than any of the HSF proposals I've seen.

If the experiment were stopped at any time unexpectedly, we would still have gained valuable information (that had appropriate controls).  Another interesting finding might be is that if those 25th generation mice from the lunar group absolutely cannot adapt back to Earth gravity immediately, we could reverse the process, ramping the g force up gradually over the course of a year or less to see if that helped the transition back.  So many other kinds of experiments you can do if you have a craft which is capable of simulating 1xg.

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Every experiment is compromised. Experimenters just make do as best they can, and hope it all averages out in the long run in a reasonable approximation of reality.

I do agree, I'm just choosing different compromises, because I don't think there's any reason to suppose that doing a 1xg control is anywhere near as expensive as you do.  I personally think the examples you raise say more about the bureaucracy of US congress/upper levels of NASA then they do about those programs.  SpaceX has shown that private space can afford to be a lot more ambitious with cost reduction when done without overbearing oversight, and one of the reasons I'm championing non-HSF missions is to avoid the oversight that would come with putting humans in these craft.

Supposing each animal chamber was self-sufficient enough to last through many generations of the model organism it was hosting (big problem, but let's take that as given in this case), what you could have is a series of "sample retrieval" capsules that are launched attached to the habitat. [...]

Alternatively, a nice bottle of LN2 to kill and freeze a certain number of the test animals after each interval. Once you freeze the last group, you can then do a single recovery of the freezer pod. You lose the "see how long it takes to re-adapt" part, but might be simpler than dozens (?) of individual return capsules.

The nice thing about euthanising with N2 is that mammals have no receptors for the gas (which normally comprises 80% of the atmosphere), so by swapping the 20% oxygen out for N2, the animals go to sleep without any distress which may otherwise affect results.  You can then flood the chamber with LN2 afterwards.  I'm agnostic as to whether this would produce better samples - I'm not assuming a huge number of returned capsules in any case.
« Last Edit: 01/30/2016 08:03 AM by mikelepage »

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