Author Topic: Zero gravity and Deep Space Habitat  (Read 9859 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 »

Offline 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 »

Offline 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.

Offline 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:


Offline 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%)?

Offline 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?

Offline 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.

Offline 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.

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #30 on: 06/04/2017 12:47 AM »
HEALTH IS FIRST,HEALTH IS SECOND.... RUSH IS A MISTAKE. AG MUST BE IMPLEMENTED FIRST.

Offline guckyfan

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Re: Zero gravity and Deep Space Habitat
« Reply #31 on: 06/04/2017 06:39 AM »
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.

I don't think an ITS can loiter on the moon for extended time and then relaunch. Moon day heat from the sun will evaporate the propellant.

I admit I don't like the idea to use moon data to extrapolate to Mars. That may be way off. Worst case  it would give inaccurate arguments against Mars. For Mars research go to Mars, not to the moon.

Offline Jim

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Re: Zero gravity and Deep Space Habitat
« Reply #32 on: 06/05/2017 12:51 AM »

Of course not. But as far as adaptations required for it, it's effectively the same.

No where close to the same thing.  There is still a gravity field and it still affects living organizations.  You don't see fish swimming in all different orientations.
« Last Edit: 06/05/2017 12:52 AM by Jim »

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #33 on: 06/05/2017 05:01 PM »
Very belated response:

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.

The test for orthostatic intolerance is not walking a short distance while still on an adrenalin high from a high-g EDL. Rather, it is a measure of the length of time you can stand upright, with a heart-rate around your resting BPM. Ten minutes is the minimum to be considered free of the condition.

Most astronauts experience some degree of orthostatic intolerance. Typically requiring one day of recovery time per mission day. However, the susceptibility varies wildly between individuals and is largely unpredictable on the ground in advance. And even recovery is kind of random, some astronauts will be considered fully recovered and cleared, but weeks later will have a random fainting spell. (And it may be worse than reported because it might damage your chances of reflight, so there's a cultural tendency to hide such issues.)

Flight surgeons I've seen speak on the subject consider micro-g adaptation to be a significant problem. Essentially, "the more we learn, the worse we realise it is."

[Worse, astronauts are strongly selected against anything that might be considered a health risk or susceptibility, based on very ad hoc standards created since the '50s (which are as much gut-feel educated guesses as actual science-based.) Long duration spaceflight research therefore has a strong selection bias that is out of the hands of researchers. So what we are "learning" may be garbage due to the lack of ability to do a proper cohort selection.]

In short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to Mars

We're already spending billions/yr on a micro-g station which isn't capable of producing high quality human weightlessness research.

As for the cost of an AG Mars transfer vessel: Because of the lack of research into low gravity and spin gravity, we don't know what the optimum numbers are (G-load/RPM). If humans only need a trace of artificial gravity, and can adapt to a fairly high RPM, then it may be that a simple tumbling-pigeon rotation of any MTV would be enough. Or for a large ship like ITS-BFS, even rotation around the long axis could be enough. No giant wheels or risky tethers required.

And such rotation may also simplify systems engineering. Water processing, air circulation and filtering, fuel transfer, sanitary systems, etc. (Prop-tank ullage only needs a milli-g load to settle the liquids. Other systems may be the same.) Simplified engineering, lower costs.

Spending a relatively small amount now to produce data on AG, might save money in the long run.
« Last Edit: 06/05/2017 05:07 PM by Paul451 »

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #34 on: 06/06/2017 01:24 AM »
PAUL 451:AGREE WITH YOU .CHECK THIS ARRANGEMENT 

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #35 on: 06/06/2017 02:15 PM »
PAUL 451:AGREE WITH YOU .CHECK THIS ARRANGEMENT

You've spammed your PDF three times in two pages. Enough.

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #36 on: 06/06/2017 02:43 PM »
Very belated response:

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.

The test for orthostatic intolerance is not walking a short distance while still on an adrenalin high from a high-g EDL. Rather, it is a measure of the length of time you can stand upright, with a heart-rate around your resting BPM. Ten minutes is the minimum to be considered free of the condition.

Most astronauts experience some degree of orthostatic intolerance. Typically requiring one day of recovery time per mission day. However, the susceptibility varies wildly between individuals and is largely unpredictable on the ground in advance. And even recovery is kind of random, some astronauts will be considered fully recovered and cleared, but weeks later will have a random fainting spell. (And it may be worse than reported because it might damage your chances of reflight, so there's a cultural tendency to hide such issues.)

Flight surgeons I've seen speak on the subject consider micro-g adaptation to be a significant problem. Essentially, "the more we learn, the worse we realise it is."

[Worse, astronauts are strongly selected against anything that might be considered a health risk or susceptibility, based on very ad hoc standards created since the '50s (which are as much gut-feel educated guesses as actual science-based.) Long duration spaceflight research therefore has a strong selection bias that is out of the hands of researchers. So what we are "learning" may be garbage due to the lack of ability to do a proper cohort selection.]

In short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to Mars

We're already spending billions/yr on a micro-g station which isn't capable of producing high quality human weightlessness research.

As for the cost of an AG Mars transfer vessel: Because of the lack of research into low gravity and spin gravity, we don't know what the optimum numbers are (G-load/RPM). If humans only need a trace of artificial gravity, and can adapt to a fairly high RPM, then it may be that a simple tumbling-pigeon rotation of any MTV would be enough. Or for a large ship like ITS-BFS, even rotation around the long axis could be enough. No giant wheels or risky tethers required.

And such rotation may also simplify systems engineering. Water processing, air circulation and filtering, fuel transfer, sanitary systems, etc. (Prop-tank ullage only needs a milli-g load to settle the liquids. Other systems may be the same.) Simplified engineering, lower costs.

Spending a relatively small amount now to produce data on AG, might save money in the long run.

You seem to have missed these parts of my comment:

"Zero gravity does come with some negative side effects, but astronauts are typically not incapacitated by them ... all the evidence suggests that we'd be pretty much fine even with 6-8 months of weightlessness."

I agree that artificial gravity tests would pay dividends later on. The OP's argument is A. weightlessness is an insurmountable obstacle to going to Mars and thus B. build my rotating space station.
"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
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Offline gospacex

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Re: Zero gravity and Deep Space Habitat
« Reply #37 on: 06/06/2017 02:59 PM »
AG is also possible on Mars.

Offline Coastal Ron

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Re: Zero gravity and Deep Space Habitat
« Reply #38 on: 06/06/2017 03:21 PM »
AG is also possible on Mars.

While true, I think artificial gravity would be significantly more complex to do on a planet with a partial gravity than it would in zero gravity. And if you have to haul the AG construction components from Earth it would make sense to just have an artificial gravity station in space around the destination planet in question than to consume fuel in taking that mass down to the planet surface.

My $0.02
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 Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #39 on: 06/06/2017 06:01 PM »
You seem to have missed these parts of my comment:
" [...] all the evidence suggests [...] "

Except you didn't respond with evidence, you responded with an anecdote of an astronaut being capable of walking for a short distance to a couch.

The statements of flight surgeons, the published research, and the comments from astronauts describing their recovery, (all discussed ad-nauseam in previous threads), suggests that the damage caused by weightlessness is worse than previously thought. We keep finding new issues, including new long term post-"recovery" damage.

Given the relatively low cost of testing AG (especially animal testing as a precursor), and the relatively low cost of adding low-g/high-RPM to a MTV, it's wasteful madness to spend many tens of billions on a Mars mission without even attempting to see if such AG would help.



AG is also possible on Mars.
While true, I think artificial gravity would be significantly more complex to do on a planet with a partial gravity than it would in zero gravity.

This has also been discussed to death previously. Being on the ground under fairly low gravity does add possibilities that aren't available for a space-habitat, because of the essentially unlimited momentum-sink of the planet. (For example, a banking rail ring.) But it assumes a large capacity for development, which assumes a pre-existing established colony/base, which assumes the problems of low-g can't be too bad. In which case, large AG habitats are probably unnecessary, and whatever the problem is (say foetal development) might be solvable with, say, two hours a day on a centrifuge-bike for the first trimester.

Offline lcasv

Re: Zero gravity and Deep Space Habitat
« Reply #40 on: 06/07/2017 01:52 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #41 on: 06/09/2017 04:46 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights
"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 RonM

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Re: Zero gravity and Deep Space Habitat
« Reply #42 on: 06/09/2017 05:15 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights

All of those are less than 500 days. So the answer is no one has done the research.

Offline TakeOff

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Re: Zero gravity and Deep Space Habitat
« Reply #43 on: 06/09/2017 11:43 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights

All of those are less than 500 days. So the answer is no one has done the research.
True. After 500 days maybe the adaptation is complete and the potential for negative health risks completely disappears. This is impossible to figure out theoretically. It has to be done in order to find out. But it should of course not be done Dr. Mengele style, but for a purpose that makes the risk of discovering the unknown worthwhile. Like spending the time on the Moon or Mars or Mars' moons. Not spending it in a nowhere Gateway.

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #44 on: 06/10/2017 01:00 PM »
But it should of course not be done Dr. Mengele style, but for a purpose that makes the risk of discovering the unknown worthwhile. Like spending the time on the Moon or Mars or Mars' moons. Not spending it in a nowhere Gateway.

So a space-station is like Auschwitz?

"Hyperbole. Not just for trajectories."

Offline TakeOff

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Re: Zero gravity and Deep Space Habitat
« Reply #45 on: 06/12/2017 01:21 PM »
But it should of course not be done Dr. Mengele style, but for a purpose that makes the risk of discovering the unknown worthwhile. Like spending the time on the Moon or Mars or Mars' moons. Not spending it in a nowhere Gateway.

So a space-station is like Auschwitz?

"Hyperbole. Not just for trajectories."
A space station that "tries out" how long humans can survive in it, really is! That's the profit from torturing people. It is completely different to send a crew out on a dangerous exploration mission that would return great discoveries if it works. The maximum potential loss is the same in both cases. The difference is that one of the cases has a possible upside. The other does not. It is a failure of design, and of humanity, to pick the latter.

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #46 on: 06/12/2017 02:20 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights

All of those are less than 500 days. So the answer is no one has done the research.

Those are just single stays. For cumulative time in space, there are currently 19 people over 500 days (soon to be 20 with Peggy Whitson becoming the first woman to reach that mark), the current record holder is Gennady Padalka, who has spent 878 days in space.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Total_time_in_space
"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 TakeOff

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Re: Zero gravity and Deep Space Habitat
« Reply #47 on: 06/12/2017 03:21 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights

All of those are less than 500 days. So the answer is no one has done the research.

Those are just single stays. For cumulative time in space, there are currently 19 people over 500 days (soon to be 20 with Peggy Whitson becoming the first woman to reach that mark), the current record holder is Gennady Padalka, who has spent 878 days in space.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Total_time_in_space
That's a Mars back and forth trip time.
Did that make Gennady Padalka lame, blind and mad? Because that is what the space hypochondriacs claim that he must be.

Offline Space Ghost 1962

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Re: Zero gravity and Deep Space Habitat
« Reply #48 on: 06/12/2017 03:51 PM »
Speaking as someone who has studied such "space hypochondriacs" issues formally, including the research at CERN on human models, and also active studies by SC from Mercury to past Pluto, I can tell you that not a one of them when asked would travel to Mars.

Offline RonM

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Re: Zero gravity and Deep Space Habitat
« Reply #49 on: 06/12/2017 05:45 PM »
Who knows what happen with astronaut's health after 500 day in zero gravity ?
No one, just guessing...

No.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Ten_longest_human_space_flights

All of those are less than 500 days. So the answer is no one has done the research.

Those are just single stays. For cumulative time in space, there are currently 19 people over 500 days (soon to be 20 with Peggy Whitson becoming the first woman to reach that mark), the current record holder is Gennady Padalka, who has spent 878 days in space.

https://en.wikipedia.org/wiki/List_of_spaceflight_records#Total_time_in_space

I knew someone would bring this up.  ::)

The question about adverse medical effects is continous time in less than Earth gravity. Obviously, cumulative time includes long periods on Earth between missions giving the body a chance to recover.

We only have data for Earth and microgravity with stays of less than 500 days. No data on lunar or Mars gravity.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #50 on: 06/13/2017 10:23 AM »

Offline RDoc

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Re: Zero gravity and Deep Space Habitat
« Reply #51 on: 09/12/2017 06:27 PM »
I'm also one who is very doubtful about long term <1.0G human viability, however, I think it should be tested.

To start with, it would seem very useful to try establishing a long term mouse/rat/etc. colony on the ISS. I realize there are serious logistical issues with this, but we really do need to know more about this stuff.

It would be even more useful to have such colonies in a centrifuge so we could see what partial G does.

The notion that we should just go to Mars or the Moon and see what happens with human pregnancy seems like a very bad idea.

Offline Patchouli

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Re: Zero gravity and Deep Space Habitat
« Reply #52 on: 09/13/2017 01:54 AM »
I think partial g research is something that needs to be looked into which is one reason I was really hyped about the Nautilus-X concept.
Also why I favor the SLS derived DSH as the larger diameter would allow for a larger centrifuge for exercising in or small animals could be placed in and observed.
« Last Edit: 09/13/2017 01:55 AM by Patchouli »

Offline dwheeler

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Re: Zero gravity and Deep Space Habitat
« Reply #53 on: 09/13/2017 04:29 AM »
I'm also one who is very doubtful about long term <1.0G human viability, however, I think it should be tested.

To start with, it would seem very useful to try establishing a long term mouse/rat/etc. colony on the ISS. I realize there are serious logistical issues with this, but we really do need to know more about this stuff.

It would be even more useful to have such colonies in a centrifuge so we could see what partial G does.

The notion that we should just go to Mars or the Moon and see what happens with human pregnancy seems like a very bad idea.

The ISS has such a facility already... the JAXA Mouse Habitat Unit or MHU. (http://spaceflight101.com/iss/mouse-habitat-experiment/). I believe it was installed in 2015 but I don't think the first mice arrived until CRS-12 just last month.

https://spaceflightnow.com/2017/08/16/station-crew-captures-dragon-supply-ship-gets-early-start-on-unpacking/

Quote
Twenty mice riding inside Dragon will be examined after their return to the ground to aid researchers studying how spaceflight affects vision and movement.

Quote
The mice will come back to Earth inside the Dragon capsule alive, and SpaceX will hand over their transporters to scientists upon return to port in Southern California.

From what I could tell in that article the centrifuge capability of the MHU wasn't needed for these particular experiments.

But anyways... a very small step in the right direction. Hopefully they have some experiments lined up that will use the centrifuge soon.

Offline tdperk

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Re: Zero gravity and Deep Space Habitat
« Reply #54 on: 09/14/2017 03:01 PM »
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.

Actually it will show that for many things there is a threshold below which there are no discernible consequences.

Offline whitelancer64

Re: Zero gravity and Deep Space Habitat
« Reply #55 on: 09/14/2017 03:39 PM »
I'm also one who is very doubtful about long term <1.0G human viability, however, I think it should be tested.

To start with, it would seem very useful to try establishing a long term mouse/rat/etc. colony on the ISS. I realize there are serious logistical issues with this, but we really do need to know more about this stuff.

It would be even more useful to have such colonies in a centrifuge so we could see what partial G does.

The notion that we should just go to Mars or the Moon and see what happens with human pregnancy seems like a very bad idea.

The ISS has such a facility already... the JAXA Mouse Habitat Unit or MHU. (http://spaceflight101.com/iss/mouse-habitat-experiment/). I believe it was installed in 2015 but I don't think the first mice arrived until CRS-12 just last month.

https://spaceflightnow.com/2017/08/16/station-crew-captures-dragon-supply-ship-gets-early-start-on-unpacking/

Quote
Twenty mice riding inside Dragon will be examined after their return to the ground to aid researchers studying how spaceflight affects vision and movement.

Quote
The mice will come back to Earth inside the Dragon capsule alive, and SpaceX will hand over their transporters to scientists upon return to port in Southern California.

From what I could tell in that article the centrifuge capability of the MHU wasn't needed for these particular experiments.

But anyways... a very small step in the right direction. Hopefully they have some experiments lined up that will use the centrifuge soon.

I think the first mice to live in JAXA's MHU were delivered on CRS-9 last year. IIRC CRS-4 was the first SpaceX delivery of mice to the ISS but I don't think they were in the MHU.
"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 RDoc

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Re: Zero gravity and Deep Space Habitat
« Reply #56 on: 10/22/2017 06:07 AM »
My understanding is that 12 young mice were kept in the MHU for 35 days to develop, 6 in the 1G centrifuge, the other 6 in microgravity. I've not found a complete report about the results, but it seems that the ones in microgravity had substantially poorer muscle development. All were returned alive and are being studied.

IMHO this is extremely important research, but doesn't cover the issue of reproduction in < 1G. The MHU only has individual cages, not what's needed for doing a multi-generational study.

Offline Coastal Ron

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Re: Zero gravity and Deep Space Habitat
« Reply #57 on: 10/23/2017 05:29 AM »
Also why I favor the SLS derived DSH as the larger diameter would allow for a larger centrifuge for exercising in or small animals could be placed in and observed.

If the SLS lifted a 8m diameter DSH I'm not sure that would be a large enough diameter to demonstrate any benefits of spin gravity.

For instance, assuming a person laid down along the inside of the outer wall (i.e. 4m from the center of rotation for a 8m diameter vessel) it would take about 5 RPM to create just 0.1 gravity. We obviously lack hard data on what can be tolerated, but I think an 8m diameter vessel is far too small to do micro-gravity testing.

Besides, at this point artificial gravity doesn't seem to be a goal for the DSG, especially since the notional missions all seem to be short duration ones, meaning zero G won't be a big problem for missions to our Moon.
« Last Edit: 10/23/2017 02:25 PM by Coastal Ron »
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 A_M_Swallow

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Re: Zero gravity and Deep Space Habitat
« Reply #58 on: 10/28/2017 10:13 AM »
Also why I favor the SLS derived DSH as the larger diameter would allow for a larger centrifuge for exercising in or small animals could be placed in and observed.

If the SLS lifted a 8m diameter DSH I'm not sure that would be a large enough diameter to demonstrate any benefits of spin gravity.

For instance, assuming a person laid down along the inside of the outer wall (i.e. 4m from the center of rotation for a 8m diameter vessel) it would take about 5 RPM to create just 0.1 gravity. We obviously lack hard data on what can be tolerated, but I think an 8m diameter vessel is far too small to do micro-gravity testing.

Besides, at this point artificial gravity doesn't seem to be a goal for the DSG, especially since the notional missions all seem to be short duration ones, meaning zero G won't be a big problem for missions to our Moon.

People are about 2 m tall so splitting the DSH down the middle into two 4m high modules should work. Expand a truss to separate the two modules. NASA has developed trusses that expand.

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #59 on: 10/28/2017 02:46 PM »
The BFS's payload pay is longer than it is wide. 8m isn't your longest available dimension.

Offline Coastal Ron

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Re: Zero gravity and Deep Space Habitat
« Reply #60 on: 10/28/2017 03:27 PM »
Besides, at this point artificial gravity doesn't seem to be a goal for the DSG, especially since the notional missions all seem to be short duration ones, meaning zero G won't be a big problem for missions to our Moon.

People are about 2 m tall so splitting the DSH down the middle into two 4m high modules should work. Expand a truss to separate the two modules. NASA has developed trusses that expand.

I'm not able to imagine what you're suggesting, but keep in mind that once you start rotating things the stresses change, and getting in or out of the rotating structure starts becoming a challenge.

Again though, artificial gravity has not been talked about for the DSH, so this is not the right thread to pursue this.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

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