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.
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.
QuoteNearly 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.
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.
Quote from: mikelepage on 05/13/2017 04:53 amMars/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.
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.
Quote from: mikelepage on 05/13/2017 08:08 amNever been a colony without babies.You are applying data points of microgravity to Mars gravity. Not a defendable position.
Quote from: mikelepage on 05/13/2017 08:08 amThis 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.
The complexity with spin gravity is minor compared to the whole Mars endeavour anyway, so I find the resistance to the concept puzzling.
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.
Quote from: mikelepage on 05/13/2017 10:26 amThe 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.
Quote from: guckyfan on 05/13/2017 11:53 amQuote from: mikelepage on 05/13/2017 10:26 amThe 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%)?
Aussie_space_nut:what do you think about this arrangement:
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
<snip>For that matter, there's never been life (that we know of) that didn't have 1xg.<snip>
Quote from: mikelepage on 05/13/2017 08:08 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.
Quote from: mikelepage on 05/15/2017 06:13 amEmphasis 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.
Quote from: Welsh Dragon on 05/15/2017 09:38 amQuote from: mikelepage on 05/13/2017 08:08 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.
Quote from: mikelepage on 05/15/2017 10:11 amQuote from: Welsh Dragon on 05/15/2017 09:38 amQuote from: mikelepage on 05/13/2017 08:08 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.Of course not. But as far as adaptations required for it, it's effectively the same.
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.
Of course not. But as far as adaptations required for it, it's effectively the same.
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.
In short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to Mars
PAUL 451:AGREE WITH YOU .CHECK THIS ARRANGEMENT
Very belated response:Quote from: whitelancer64 on 05/01/2017 08:28 pmCounterpoint: 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.]Quote from: whitelancer64 on 05/01/2017 08:28 pmIn short, there's little reason to spend billions designing, building, testing a rotating spacecraft to go to MarsWe'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.
AG is also possible on Mars.
You seem to have missed these parts of my comment: " [...] all the evidence suggests [...] "
Quote from: gospacex on 06/06/2017 02:59 pmAG 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.
Who knows what happen with astronaut's health after 500 day in zero gravity ?No one, just guessing...
Quote from: lcasv on 06/07/2017 01:52 pmWho 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
Quote from: whitelancer64 on 06/09/2017 04:46 pmQuote from: lcasv on 06/07/2017 01:52 pmWho 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_flightsAll of those are less than 500 days. So the answer is no one has done the research.
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.
Quote from: TakeOff on 06/09/2017 11:43 pmBut 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."
Quote from: RonM on 06/09/2017 05:15 pmQuote from: whitelancer64 on 06/09/2017 04:46 pmQuote from: lcasv on 06/07/2017 01:52 pmWho 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_flightsAll 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'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.
Twenty mice riding inside Dragon will be examined after their return to the ground to aid researchers studying how spaceflight affects vision and movement.
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.
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.
Quote from: RDoc on 09/12/2017 06:27 pmI'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/QuoteTwenty mice riding inside Dragon will be examined after their return to the ground to aid researchers studying how spaceflight affects vision and movement.QuoteThe 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.
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.
Quote from: Patchouli on 09/13/2017 01:54 amAlso 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.
Quote from: Coastal Ron on 10/23/2017 05:29 amBesides, 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.
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.
Maybe we could tether a couple of Dragon/Orions and put a couple of crew in them for 1-2-3 month missions.
I would argue though that we can simulate these loads. And something no one here has picked up on is that in a space ship with modest spin gravity its a lot easier to do this. You don't need to be strapped into place with rubber bands. All you do is wear enough mass. Now you've got 1g equivalent loads but you have mobility.
Test it with mice in centrifuge at 0.4G, in ISS?
In short a spacecraft with a sense of up and down is more orderly and less stressful and people are less likely to be sick or suffer psycholigical issues.
Since I've argued for a modest level of spin g it also follows that you do not need long structures. A structure that is 40m long rotated st 4.2rpm will deliver Mars equivalent g.
Quote from: Russel on 01/10/2018 04:31 amI would argue though that we can simulate these loads. And something no one here has picked up on is that in a space ship with modest spin gravity its a lot easier to do this. You don't need to be strapped into place with rubber bands. All you do is wear enough mass. Now you've got 1g equivalent loads but you have mobility. That is so wrong. That does nothing for internal organs, brain, and the vestibular system. And it doesn't over the whole muscular skeleton system.
Globus and Hall write that rotations up to 10 rpm may be acceptable with training.If you only want Mars gravity for transit, 8.2 rpm would be fine.
Nonetheless; they should strive to make any rotating artificial-grav structure large as practically possible
In the Engle, Simon & Clark presentation above, they were able to crank the rpm tolerance up to 17RPM for the most queasy subjective after training, and they still retained their adaptation after 30 days.
Quote from: MATTBLAK on 01/31/2018 02:55 amNonetheless; they should strive to make any rotating artificial-grav structure large as practically possibleWhy do you assume the FISO/Boeing concept isn't "as large as practically possible"? Given that "practical" and "possible" include things like cost, launch vehicles, likelihood of getting approval, logistics of mating with the larger station/vehicle, etc.
Quote from: Paul451 on 01/31/2018 02:24 pmQuote from: MATTBLAK on 01/31/2018 02:55 amNonetheless; they should strive to make any rotating artificial-grav structure large as practically possibleWhy do you assume the FISO/Boeing concept isn't "as large as practically possible"? Given that "practical" and "possible" include things like cost, launch vehicles, likelihood of getting approval, logistics of mating with the larger station/vehicle, etc.It may be "as large as practically possible" if you assume it must be launched in one piece.
Hab <dock> Link <dock> Hab
It can host additional fuel or propulsion systems for instance.
It surprises me that this configuration is being overlooked.
Something prepared earlier for another thread. [...]
PERHAPS if an astronaut is able to sleep in 1g then all the 0g issues will disappear.
Quote from: Russel on 02/02/2018 01:01 amHab <dock> Link <dock> HabUsually the "link" is called a "node", or "docking node".Quote from: Russel on 02/02/2018 01:01 amIt can host additional fuel or propulsion systems for instance.At least it could host the power system. With the solar arrays "hanging" in the rotational plane.Quote from: Russel on 02/02/2018 01:01 amIt surprises me that this configuration is being overlooked.I don't think it's been overlooked. Look up the various spin-gravity threads, usually in the Advanced Concepts section. People have played with seemingly every possible configuration. This one is a pretty basic option, usually called a "dumbbell". I scratched one out ages ago (see below), when I needed to explain what I meant about the arrays "hanging" in the rotational plane. (People always seem to forget about power/etc with a rotating station.)We've also previously discussed issues with this layout. For example, if you have an unbalanced mass (such as a capsule) docked on the rotational axis, it will destabilise the system, causing it to periodically flip the rotational plane 180° every so often.
Quote from: Aussie_Space_Nut on 02/02/2018 11:24 pmPERHAPS if an astronaut is able to sleep in 1g then all the 0g issues will disappear.Backwards. We use bedrest to simulate zero-g health effects on Earth. Sleeping under gravity does nothing to reverse or prevent zero-g issues.You want to do standing/moving work and exercise under gravity, then have sleep and sitting/lounging activities in low/zero gravity.
No recliner here on earth can or ever will be "zero gravity".
5 pages of people trying to re-invent the wheel. As many in the past have pointed out - rotate a pressurized habitat linked to an empty upper stage via a few hundred feet of tethering. Quite large radii of rotation are possible with tethers.
Quote from: DaveJes1979 on 12/03/2018 06:40 pm5 pages of people trying to re-invent the wheel. As many in the past have pointed out - rotate a pressurized habitat linked to an empty upper stage via a few hundred feet of tethering. Quite large radii of rotation are possible with tethers.Yes I agree. For those who want to have a backup habitat module in case there is a problem, just have two side by side with an airlock between them on the same side of the spin arm and extend the cable with the counter weight a little further out and/or adjust the centre of spin on the cable.For concerns about people, liquids and things moving about and disturbing the rotational balance, I would have thought that many such movements would cancel themselves out eventually and that the residual imbalances could be dealt with by an automated system monitoring the rotational forces in 3 dimensions and adjusting counter weights inside or outside of the craft and or increasing / decreasing the rate of spin.
Yes I agree. For those who want to have a backup habitat module in case there is a problem, just have two side by side with an airlock between them on the same side of the spin arm and extend the cable with the counter weight a little further out and/or adjust the centre of spin on the cable.
For concerns about people, liquids and things moving about and disturbing the rotational balance, I would have thought that many such movements would cancel themselves out eventually and that the residual imbalances could be dealt with by an automated system monitoring the rotational forces in 3 dimensions and adjusting counter weights inside or outside of the craft and or increasing / decreasing the rate of spin.
Quote from: Slarty1080 on 12/06/2018 04:37 pmYes I agree. For those who want to have a backup habitat module in case there is a problem, just have two side by side with an airlock between them on the same side of the spin arm and extend the cable with the counter weight a little further out and/or adjust the centre of spin on the cable.The Dragon or Starliner capsule that brought you to the habitat is the backup. Just like with ISS, you get into it and return to earth in the event of an emergency. There will have to be a specialized docking adapter and structural provisions to connect the capsule to the habitat.QuoteFor concerns about people, liquids and things moving about and disturbing the rotational balance, I would have thought that many such movements would cancel themselves out eventually and that the residual imbalances could be dealt with by an automated system monitoring the rotational forces in 3 dimensions and adjusting counter weights inside or outside of the craft and or increasing / decreasing the rate of spin.You already have to have an RCS to spin up the stack in the first place. No need to add more mass and complexity.
But why is that necessary for such a small habitat, with a trained crew?
Quote from: Paul451 on 12/11/2018 07:40 amBut why is that necessary for such a small habitat, with a trained crew?Tethers are light.
Also, who says you will have a trained crew (rather than untrained passengers on the way to Mars)?
But unstable and historically error-prone.
(The best "tether" option seems to be to combine it with a pressurised tube to put the tethers/cables under tension, tethers to put the pressure-tube under compression. Increases the vibrational and twisting stability over either alone.)
The topic of the thread, DSH.