Author Topic: Zero gravity and Deep Space Habitat  (Read 2051 times)

Offline lcasv

Zero gravity and Deep Space Habitat
« on: 05/01/2017 07:57 PM »
We all know the consequences of long-term exposure to weightlessness.
Two examples:

" In 1984, after a 237-day mission, Soviet cosmonauts felt that if they had stayed in space much longer they might not have survived reentry [3]. In 1987, in the later stages of his 326-day mission, Yuri Romanenko was highly fatigued, both physically and mentally. His work day was reduced to 4.5 hours while his sleep period was extended to 9 hours and daily exercise on a bicycle and treadmill consumed 2.5 hours. At the end of the mission, the Soviets implemented the unusual procedure of sending up a "safety pilot" to escort Romanenko back to Earth"
Many of these changes do not pose problems as long as the crew remains in a weightless environment. Trouble ensues upon the return to life with gravity. The rapid deceleration during reentry is especially stressful as the apparent gravity grows from zero to more than one "g" in a matter of minutes.

So, zero gravity has to be solved before thinking in long trips.There is not reason spend billions with out getting artificial gravity.
Copy from permanent.com


Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #1 on: 05/01/2017 08:28 PM »
Counterpoint:

After spending 437 days in space (on Mir in 1994-1995) Valeri Polyakov got out of his Soyuz capsule and walked to the recovery couch. "Upon landing, Polyakov opted not to be carried the few feet between the Soyuz capsule and a nearby lawn chair, instead walking the short distance. In doing so, he wished to prove that humans could be physically capable of working on the surface of Mars after a long-duration transit phase."

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

Nearly all astronauts are able to walk and do other activities after a short period of resting to allow blood flow and other bodily fluids to normalize with Earth's gravity.

Zero gravity does come with some negative side effects, but astronauts are typically not incapacitated by them. One of the major breakthroughs on the ISS has been to show that consistent daily exercise reduces muscular and skeletal atrophy. Most other side effects are minor or irritating (like flatulence) but aren't really a big hazard to human health.

In short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to Mars when all the evidence suggests that we'd be pretty much fine even with 6-8 months of weightlessness.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #2 on: 05/01/2017 08:54 PM »
Agree with you, spending billions in rotating spacecraft is to much. Better solution is a simple arrangement to test artificial gravity. Check this file what is your opinion.

Offline TripD

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Re: Zero gravity and Deep Space Habitat
« Reply #3 on: 05/02/2017 12:09 AM »
Quote
Nearly all astronauts are able to walk and do other activities after a short period of resting to allow blood flow and other bodily fluids to normalize with Earth's gravity.

I only take issue with this in that, upon landing on Mars there may be a need for the crew to have 'pep' in their step.

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #4 on: 05/02/2017 09:35 PM »
Agree with you, spending billions in rotating spacecraft is to much. Better solution is a simple arrangement to test artificial gravity. Check this file what is your opinion.

Two things:

One, this presentation doesn't look simple at all. It looks like there's a large amount of structure along with many moving parts.

Two, you say it's "a new approach," but it looks very much like many other proposals I have seen before.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #5 on: 05/02/2017 09:39 PM »
Quote
Nearly all astronauts are able to walk and do other activities after a short period of resting to allow blood flow and other bodily fluids to normalize with Earth's gravity.

I only take issue with this in that, upon landing on Mars there may be a need for the crew to have 'pep' in their step.

I don't think there's any way around it. The astronauts are going to have to spend some period of time in a weightless environment prior to Mars EDL (I'd say at least a couple weeks to avoid having space-sick people during EDL), and so they'll need to spend some time resting to reacclimatize to gravity. The major reason is to avoid the astronauts passing out from blood draining away from the head.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline KelvinZero

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Re: Zero gravity and Deep Space Habitat
« Reply #6 on: 05/12/2017 07:06 AM »
One of my pet ideas is VR booths.

Even if you had gravity, that isn't the same as space or reason to walk or run. VR could give you the impression of a large open expanse to explore, something you would never be able to physically build into a spaceship.

The current approach of elastic bands and treadmills seems reasonable to me. I think that should be enough to solve most issues. But instead of a couple of hours exercise a day I think you could aim for a set up comfortable and entertaining enough for people to spend 8 hours a day in, in a choice of vast shared (or private) environments.

Also these vr booths could be useful for teleoperation and entertainment at the destination.

I think this is a really important, solvable problem. People could possibly live healthily (including mental health) in volumes no larger than what they can reach with outstretched arms. There is no fundamental obstacle like the rocket equation.

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #7 on: 05/13/2017 04:53 AM »
Several threads already exist for this topic in the advanced section:

The big one, that we agreed to limit to discussion of human space flight spin gravity demos:
http://forum.nasaspaceflight.com/index.php?topic=34036.0

The thread I started specifically for Non human space flight engineering/bio demos:
http://forum.nasaspaceflight.com/index.php?topic=39358.0

As well as:
http://forum.nasaspaceflight.com/index.php?topic=37026.0
http://forum.nasaspaceflight.com/index.php?topic=37025.0
http://forum.nasaspaceflight.com/index.php?topic=40448.0
http://forum.nasaspaceflight.com/index.php?topic=39971.0

As a counter-counterpoint to Valeri Polyakov (who is always brought up in these conversations) it is worth noting that the muscular/skeletal problems of microgravity are both the first to occur and the easiest to solve.

The serious clinical symptoms of zero-gravity are only expected to occur (in adults) after multiple years of microgravity:


Also, mammalian pregnancy is adversely affected,
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0006753
as is immune system function and eye function.

The point is that 2-3 year Mars missions are probably quite possible with regular exercise as used on ISS.  Mars/Moon/Space colonisation probably isn't, so spin gravity is a problem we will have to solve, sooner or later.

Icasv, your plan is a 2+ billion dollar mission.  We can do better.
« Last Edit: 05/13/2017 04:58 AM by mikelepage »

Online guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #8 on: 05/13/2017 05:33 AM »
The point is that 2-3 year Mars missions are probably quite possible with regular exercise as used on ISS. 

OK.

Mars/Moon/Space colonisation probably isn't, so spin gravity is a problem we will have to solve, sooner or later.

How do you get to this conclusion?

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #9 on: 05/13/2017 08:08 AM »
Mars/Moon/Space colonisation probably isn't, so spin gravity is a problem we will have to solve, sooner or later.

How do you get to this conclusion?

Never been a colony without babies.
For that matter, there's never been life (that we know of) that didn't have 1xg.

Null hypothesis has to be that at least some gravity is required for sustained life (=colonisation).  An n of ~530 healthy adults, all of which had some symptoms directly resulting from absence of gravity for even short periods of time, does nothing to disprove the null hypothesis.  Extrapolating from current data suggests that even in healthy adults with regular exercise regimes, symptoms will reach clinical significance after microgravity stays of 3+ years.

This ain't rocket science.  Launching spin-gravity habitats is only limited by mass/launch costs, so the obvious solution ain't rocket science either.
« Last Edit: 05/13/2017 08:11 AM by mikelepage »

Online guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #10 on: 05/13/2017 08:43 AM »
Never been a colony without babies.

You are applying data points of microgravity to Mars gravity. Not a defendable position.

This ain't rocket science.  Launching spin-gravity habitats is only limited by mass/launch costs, so the obvious solution ain't rocket science either.

Don't make up needs for a Mars colony like this. There is no supporting data whatsovever indicating that something that complex is needed. Talk about it once there are data and they show it is needed.

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #11 on: 05/13/2017 10:26 AM »
Never been a colony without babies.

You are applying data points of microgravity to Mars gravity. Not a defendable position.

A null hypothesis is the only defensible position until new evidence comes to light.  We only have solid data for 1xg.  I'm not saying we shouldn't try to get that new evidence at Mars gravity btw, just that its irresponsible to plan your mission on the hunch that it will be okay.

Quote
This ain't rocket science.  Launching spin-gravity habitats is only limited by mass/launch costs, so the obvious solution ain't rocket science either.

Don't make up needs for a Mars colony like this. There is no supporting data whatsovever indicating that something that complex is needed. Talk about it once there are data and they show it is needed.

We can make predictions based on what we know about biology.  Even the simplest multicellular organisms are acutely aware of up/down directionality.  Developing embryos/seedlings/spores use this sense to structure growth and development.  Given that most biological sensors are not binary on/off switches, but sensors of degree, it would be incredibly surprising if there weren't some issues with partial Mars gravity. 

The experiments on Mars will be to figure out how to stop these issues being show-stoppers, not whether they are problems in the first place.  The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.

Online guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #12 on: 05/13/2017 11:53 AM »
The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.

I find it puzzling how people insist on AG without a trace of evidence it is needed.

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #13 on: 05/13/2017 12:38 PM »
"Things that are not sustainable in the long run will fail".There are not shortcuts.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #14 on: 05/14/2017 12:12 AM »
It freaks me out that people are seriously planning going to Mars without first doing an artificial Mars gravity long term stay experiment somewhere, somehow.

I would have thought this would be at the very least a massive risk to any "Mars Colony Business Plan" if nothing else.

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #15 on: 05/14/2017 12:21 AM »
100 % agree.Many things can happen about health in 500 days in zero gravity

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #16 on: 05/14/2017 01:14 AM »

Aussie_space_nut:

what do you think about this arrangement:


Online guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #17 on: 05/14/2017 04:50 AM »
It freaks me out that people are seriously planning going to Mars without first doing an artificial Mars gravity long term stay experiment somewhere, somehow.

I would have thought this would be at the very least a massive risk to any "Mars Colony Business Plan" if nothing else.

There is a risk to it, yes. But do you seriously believe it is feasible to build a space station and let people live there for many years? It takes at least as much time as 10 years to establish a child can grow up healthy. Better really for a whole generation. That's absurd in cost and time. Much better to go to Mars and try it there.

If you mean just some short generation animal tests with mice or such, I agree. That should be done and I hope it will be done during a long term test flight of ITS in cislunar space.

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #18 on: 05/14/2017 05:00 AM »
The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.

I find it puzzling how people insist on AG without a trace of evidence it is needed.

I'm curious what you think the threshold is then? We have strong evidence that long term zero-gravity exposure is harmful long-term in spite of regular exercise, and three centuries of biology research will tell you these effects always exist on a sliding scale.

So if you're sure enough that Mars (38.9%) gravity is okay to plan a long-term mission without spin-g, do you think Moon-gravity (16.6%) is okay long term? What about Ceres surface gravity (2.8%)?  Or Phobos surface gravity (0.6%)?

Online Coastal Ron

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Re: Zero gravity and Deep Space Habitat
« Reply #19 on: 05/14/2017 05:26 AM »
The purpose of the ISS is to collect information about the effects of zero-G on humans, and to test solutions.  However we have not had a large enough sample size to truly understand what the effects will be on random humans during potential missions to Mars.

And since any crews being sent to Mars will likely consist of both men and women, it's important to know that men and women don't experience the same side effects from zero-G.  Here is an article that talks about it:

We're Ignoring Women Astronauts' Health At Our Peril - Gizmodo

Nevertheless I think there will be plenty of qualified volunteers that will be willing to go, because that is human nature at it's best - willing to take risks in order to benefit humanity as a whole.

And while I think initially we will not use artificial gravity systems due to their great cost, I think eventually they will be required by humanity in order to mitigate the long-term effects of no or reduced gravity on the human body as we expand out into the solar system.  Going to be a few years before we can build artificial gravity structures though, so we're going to have to rely on volunteers to help us understand what the limits of the human body are...
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 guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #20 on: 05/14/2017 08:52 AM »
The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.

I find it puzzling how people insist on AG without a trace of evidence it is needed.

I'm curious what you think the threshold is then? We have strong evidence that long term zero-gravity exposure is harmful long-term in spite of regular exercise, and three centuries of biology research will tell you these effects always exist on a sliding scale.

So if you're sure enough that Mars (38.9%) gravity is okay to plan a long-term mission without spin-g, do you think Moon-gravity (16.6%) is okay long term? What about Ceres surface gravity (2.8%)?  Or Phobos surface gravity (0.6%)?

I am not sure Mars gravity is enough. But I think there is a very good chance. Humans have proven over and over to be very adaptable. With moon gravity I am less confident but whoever is interested in settling the moon can try that.

I just say doing a multi year test with humans in spin gravity is absurd and absurdly expensive in money and time. It needs to be done on Mars.

Spin gravity for pregnancies on Mars may technically not the biggest obstacle. But it would be a severe disruption of social life and much harder to justify and find people willing to go there. Spin gravity for in space settlements no doubt is needed. Multi year manned expeditions to the outer solar system may or may not require it. I guess yes it will be needed with flight times beyond 2 or 3 years.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #21 on: 05/14/2017 10:16 AM »

Aussie_space_nut:

what do you think about this arrangement:



I'm a big fan of keeping things as simple as possible. So having moving "cars" travelling between habs etc I think is just way too complicated. Especially if things go wrong. I like the idea of a fixed and ridgid structure that would allow you to move anywhere inside just in normal clothes.

Nothing is impossible if you throw enough resources at it I suppose.

But I think a fixed structure is way easier to engineer in a safe manner than what you propose which has multiple opportunities for a docking failure, a car to get stuck, etc. Therefore you have to plan for a way to rescue the occupants both in the car and those stranded elsewhere.

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #22 on: 05/15/2017 06:13 AM »
I am not sure Mars gravity is enough. But I think there is a very good chance. Humans have proven over and over to be very adaptable. With moon gravity I am less confident but whoever is interested in settling the moon can try that.

I just say doing a multi year test with humans in spin gravity is absurd and absurdly expensive in money and time. It needs to be done on Mars.

Spin gravity for pregnancies on Mars may technically not the biggest obstacle. But it would be a severe disruption of social life and much harder to justify and find people willing to go there. Spin gravity for in space settlements no doubt is needed. Multi year manned expeditions to the outer solar system may or may not require it. I guess yes it will be needed with flight times beyond 2 or 3 years.

Emphasis mine, just to point out that you can't say I have no evidence that low gravity on Mars is harmful, and then come out with a statement like that ;)

I agree humans are adaptable, but Mars gravity is nearly down to a third of biological norms.  I struggle to think of any situation where humans have shown themselves to be that adaptable for long-term undertakings. 

Caloric restriction diets of typically only cut 20-40% of calories, since 50% restriction diets (in rodents at least) attract mortality rates of 50%.  The highest altitude where people have adapted to living (Everest Base camp =6000m) is ~50% atmospheric pressure, and that's only after generations of Nepalese sherpas have become used to living upwards of 4000m. (I choose these examples because these are both things where "mind over matter" runs up against strict biological limits).

In answer to my own question above, I'm guessing the threshold for long-term low gravity adaptation (at least in the first generation of space travellers) is somewhere between 50-75% of Earth gravity, perhaps even as high as 90%.  I would bet that long term colonisation or Mars is going to need a multigenerational adaptation process.

Or perhaps humans will (for the foreseeable future) be like salmon returning upstream to spawn, needing to return to near-1g spin habitats in Mars orbit in order to have children.

Online guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #23 on: 05/15/2017 07:10 AM »

Emphasis mine, just to point out that you can't say I have no evidence that low gravity on Mars is harmful, and then come out with a statement like that ;)

This is getting annoying. My statements are totally consistent. I I never said we have positive proof either direction. It is you who demands a huge cost layout in money and time to try this in AG that IMO are better done in the real martian environment.

Just imagine having an AG environment set up and maintained long enough that children can be born and raised there, just to prepare for getting to Mars, on the assumption it will fail.


Offline Welsh Dragon

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Re: Zero gravity and Deep Space Habitat
« Reply #24 on: 05/15/2017 09:38 AM »
<snip>
For that matter, there's never been life (that we know of) that didn't have 1xg.

<snip>
Except of course all aquatic life.

Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #25 on: 05/15/2017 10:11 AM »
<snip>
For that matter, there's never been life (that we know of) that didn't have 1xg.

<snip>
Except of course all aquatic life.

Neutral buoyancy !=! zero gravity.


Offline mikelepage

Re: Zero gravity and Deep Space Habitat
« Reply #26 on: 05/15/2017 10:31 AM »

Emphasis mine, just to point out that you can't say I have no evidence that low gravity on Mars is harmful, and then come out with a statement like that ;)

This is getting annoying. My statements are totally consistent. I I never said we have positive proof either direction. It is you who demands a huge cost layout in money and time to try this in AG that IMO are better done in the real martian environment.

Just imagine having an AG environment set up and maintained long enough that children can be born and raised there, just to prepare for getting to Mars, on the assumption it will fail.

Yes it is getting annoying.  It is you saying I'm demanding things I've never asked for.  :(

By all means, I hope SpaceX/NASA/whoever will get to Mars as soon as possible, without AG, because that will most likely be the easiest/quickest way to get it done.  Do science on Mars, explore etc etc.  I'm the last person to get in the way of that.

That said, myself and many other evolutionary biology trained types are dubious about the gravity situation.  We suspect there's a very good chance that some kind of spin gravity will be necessary.  So, in parallel with Mars efforts, we want to set up a lab in LEO/wherever to do AG research, such that if the less-optimistic scenario turns out to be true, we've got a head start on the years of work that will need doing.  If Mars gravity turns out to be fine, then none of the work is wasted anyway, because it helps us build space settlements.

There need not be any conflict between our positions.  I'm just trying to get you to acknowledge where I'm coming from.
« Last Edit: 05/16/2017 04:59 AM by mikelepage »

Offline Welsh Dragon

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Re: Zero gravity and Deep Space Habitat
« Reply #27 on: 05/15/2017 12:39 PM »
<snip>
For that matter, there's never been life (that we know of) that didn't have 1xg.

<snip>
Except of course all aquatic life.

Neutral buoyancy !=! zero gravity.
Of course not. But as far as adaptations required for it, it's effectively the same.

Offline A_M_Swallow

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Re: Zero gravity and Deep Space Habitat
« Reply #28 on: 05/15/2017 12:56 PM »
<snip>
For that matter, there's never been life (that we know of) that didn't have 1xg.

<snip>
Except of course all aquatic life.

Neutral buoyancy !=! zero gravity.
Of course not. But as far as adaptations required for it, it's effectively the same.

Not necessarily. Mammals and fish are nearly symmetrical left to right but they are very different top to bottom. So individual cells and entire organs probably need to know where they are vertically. Even in water gravity can be used to determine which way is up and which may is down - an inert mass will try to sink to the bottom of the cell.

Offline RonM

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Re: Zero gravity and Deep Space Habitat
« Reply #29 on: 05/15/2017 04:52 PM »
A small base on the Moon would allow research into medical effects of 1/6 gee in addition to lunar exploration. It would be interesting to see if such a low gravity reduces or eliminates the issues we have in microgravity. It would provide a third data point to extrapolate the effects of Mars gravity to give us an idea before we run experiments on Mars.

There's international support for some sort of gateway station in lunar orbit. A gateway station and reusable lander would make lunar exploration easier.

SpaceX could land an ITS ship on the Moon, let it sit for a few months as a temporary base, and go back to Earth. They probably want to do some cislunar testing before heading to Mars anyway.

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