Author Topic: Zero gravity and Deep Space Habitat  (Read 28542 times)

Offline Russel

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Re: Zero gravity and Deep Space Habitat
« Reply #80 on: 02/01/2018 12:34 AM »
Nonetheless; they should strive to make any rotating artificial-grav structure large as practically possible

Why 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. I'll simply repeat that is a questionable assumption.

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #81 on: 02/01/2018 04:56 PM »
Nonetheless; they should strive to make any rotating artificial-grav structure large as practically possible
Why 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.

(I might have misread the presentation, but I thought it was launched in two pieces, the rotator/hub and the mushroom, both designed to fit separately into a Dragon trunk.)

But I repeat, there are other issues, including reasonable funding expectation (which includes the biases of funders), the object you are mating the test system to (ISS - which includes all of the parties you have to get to agree to it), and I'll add commonality between the largest "practical" test system and a subsequent working system.

Just because you can imagine a giant assembled AG space-station doesn't mean it's "practical" or "possible", given those other constraints.

I mean, I have suggested variants of, say, a BA-330 that remains attached to its upper-stage as counterweight, flying separately from ISS, spinning as a baton/tumbling-pigeon. Or Hab, docking-node, ECLSS/power/utility module, launched separately. But just because I can picture it, doesn't mean that anyone would be interested in funding it.

Offline Russel

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Re: Zero gravity and Deep Space Habitat
« Reply #82 on: 02/02/2018 01:01 AM »
I don't really want to go into thr politics of this. Suffice to say I'm not from the US and I hope good engineering wins over US political/commercial machinations.

What I think makes sense is the following.  Start with a basic module. Call it a hab for want of a better term. Send 2 of these into orbit. Now construct a link module which at its most basic is a tube with docking ports on either end. Send that into orbit and perform standard focking.

Hab <dock> Link <dock> Hab

Now you have a structure that can be rotated around its point of symmetry - the center of the link module.

15m from the center of rotation at 5rpm delivers 0.4g. 20m and 7rpm felivers 1g.

Not only is this simple and practical but it delivers other benefits. Firstly is scaling. For a given width constraint you get twice the hab volume. Or put another way, each hab can be smaller than the required single unit hab.

Secondly you've added redundancy with basic power and life support replicated. In an emergency, the crew can transfer into one hab (cramped) and there are many scenarios where not having this redundancy means loss of crew.

The link module can be as simple or as complex as you like. It can host additional fuel or propulsion systems for instance. It can also host comms equipment.

It surprises me that this configuration is being overlooked.

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #83 on: 02/02/2018 04:25 AM »
Hab <dock> Link <dock> Hab

Usually the "link" is called a "node", or "docking node".

It 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.

It 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.

Offline Hotblack Desiato

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Re: Zero gravity and Deep Space Habitat
« Reply #84 on: 02/02/2018 01:14 PM »
How about emulating gravity instead of simulating gravity by spin.

The spaceship/DSH/ITS/whatever is built with floors, as if there was gravity and all persons wear powered exoskeletons which emulate the gravity.

So, the wearers will feel a constant force more or less as if they move at 1g. Of course, the heart will not be forced to pump against gravity, and stuff will still be weightless (but that can be solved via other means). The boots will need some sort of electromagnetism, cleverly switched on and off to emulate that they are sticking on the floor.

These exoskeletons will have a second purpose: on Mars, they will serve as regular exoskeletons assisting for heavy lifting (even at 0.38g, there will be really heavy stuff on Mars).

I got that idea from a german magazine called "Bild der Wissenschaft" where they did an article about a young guy named Samuel Koch, who had a tragic accident in a german TV show named "Wetten dass..." which rendered him tetraplegic. He is now testing powered exoskeletons which give him back the ability to walk, and prevent his muscles from atrophying away.

https://de.wikipedia.org/wiki/Samuel_Koch (in german)

This can also be augmented with VR-googles, making people believe that they are somewhere else, or doing sports, etc.

And it would be interesting for Moon or Ceres, where the regular gravity might be too low (maybe even the martian gravity is too low for us)

something very similar:

https://www.extremetech.com/extreme/241613-walking-hyundais-exoskeleton-helps-paraplegics-move
« Last Edit: 02/02/2018 01:30 PM by Hotblack Desiato »

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #85 on: 02/02/2018 10:52 PM »
Something prepared earlier for another thread.

Spinforce Calculator is here,
http://www.calctool.org/CALC/phys/newtonian/centrifugal
« Last Edit: 02/02/2018 11:07 PM by Aussie_Space_Nut »

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #86 on: 02/02/2018 11:06 PM »
Something prepared earlier for another thread. [...]

Why limit it to 3rpm? At just 4rpm you can cut the diameter in half.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #87 on: 02/02/2018 11:11 PM »
Agreed.

My point was that in a single launch you could have a rigid "tube" 100m long. It's doable. Anything shorter is also doable of course.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #88 on: 02/02/2018 11:24 PM »
Another option for a large habitat such as a Bigelow Olympus is a spin gravity section located within.

PERHAPS if an astronaut is able to sleep in 1g then all the 0g issues will disappear. (OK. Thats a huge assumption.)

According to Wikipedia,
The Bigelow Olympus is 12.6m Diameter.
So if we build a spin gravity structure within at say 10m Diameter, 5m Radius then spin it up to 13 RPM we get 1g.

We know some humans can handle that, thinking of motorcycle riders inside the wall of death attractions.

However it is not ideal.

https://en.wikipedia.org/wiki/BA_2100

« Last Edit: 02/02/2018 11:25 PM by Aussie_Space_Nut »

Offline Jim

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Re: Zero gravity and Deep Space Habitat
« Reply #89 on: 02/02/2018 11:37 PM »
Not really, handle and live in ate two different things

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #90 on: 02/03/2018 12:07 AM »
Agreed Jim. It's a huge assumption to think that astronauts can sleep in a 13RPM 1g environment.

Offline Paul451

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Re: Zero gravity and Deep Space Habitat
« Reply #91 on: 02/03/2018 12:57 AM »
PERHAPS 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.

Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #92 on: 02/03/2018 01:33 AM »
Ha! That blows my point right out of the water then! :-)

Ahhhhh well.

Offline Russel

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Re: Zero gravity and Deep Space Habitat
« Reply #93 on: 02/04/2018 01:57 AM »
Hab <dock> Link <dock> Hab

Usually the "link" is called a "node", or "docking node".

It 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.

It 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.

My access to Advanced Concepts is read only so I haven't given it much of a look.

I don't mind calling it a Node but I prefer 'module' to emphasise the on-orbit docking process.

It certainly would host solar arrays. However the hab modules need a 'degraded mode' backup power and energy storage system on their own.

The intention is to only break symmetry (by docking) whilst not spinning.

I don't know of any proposed mission that incorporates spin gravity other than the original 'spin around a spent booster using cables' idea. The thing that really attracts me to the "dumbell" configuration is identical modules which gives payoffs in terms of development costs and tobustness/safety.

Offline Russel

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Re: Zero gravity and Deep Space Habitat
« Reply #94 on: 02/04/2018 03:59 AM »
PERHAPS 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.

I tend to agree with this. You spend the majority of your time not sleeping.If a vehicle provided 0.4g in working quarters and 0.2 g in sleeping quarters I'd be happy.


Offline Aussie_Space_Nut

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Re: Zero gravity and Deep Space Habitat
« Reply #95 on: 03/04/2018 01:05 AM »
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.

This paper is a very good read, thank you QuantumG :-)

Offline Yamaur

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Re: Zero gravity and Deep Space Habitat
« Reply #96 on: 09/20/2018 01:34 PM »
No recliner here on earth can or ever will be "zero gravity". My main thought is that a recliner that moves up and down with the weight of you and shifting body position will simply introduce a lot of wobble to your views as it adjusts to your movement.
I've recently purchased a riser recliner for my husband as he was starting to show occasional signs of struggling to get out of his usual armchair. I just wanted to make sure that something was in place to help me get him out of his chair if necessary.

He doesn't tend to nap during the daytime yet, unless he is ill, but again I thought it worth going for the recliner option so that it isn't a problem in future should he start to struggle getting up to bed.

They aren't cheap https://10restbest.com/best-zero-gravity-chair ( :eek: )but we put his PIP money aside to save up for it - I'm also justifying the cost by telling myself it might be something I can use for myself in future, as they are easy enough to get re-covered.

I steered away from leather for several reasons - the ones I saw were nearly all in black or brown which are colours my husband struggles to 'see', so not ideal trying to get him to sit on something he thinks might be a black hole! I think they probably do beige/cream ones too but I remember a cream leather sofa my brother used to have and it looked quite grubby and worn fairly early on. His wife also used to complain that she found it hot and sticky, particularly in warm weather.

Also I don't know what effect urine would have on leather or the effect of cleaning products to try and remove the smell of urine from leather (my husband isn't incontinent but I know it is a possibility in future).


« Last Edit: 09/21/2018 10:14 AM by Yamaur »

Offline QuantumG

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Re: Zero gravity and Deep Space Habitat
« Reply #97 on: 09/21/2018 01:47 AM »
No recliner here on earth can or ever will be "zero gravity".

There's ways you can do zero-g with magnetic fields - they do it for medical research, but it'll probably never be human-scale. Neutral buoyancy is good enough for most practical uses (training etc). Considering the effect on your bones, just extended bed rest is enough to get the same effect as zero-g.

BTW - welcome to the forum!
Human spaceflight is basically just LARPing now.

Offline DaveJes1979

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Re: Zero gravity and Deep Space Habitat
« Reply #98 on: 12/03/2018 06:40 PM »
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.

Online Slarty1080

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Re: Zero gravity and Deep Space Habitat
« Reply #99 on: 12/06/2018 04:37 PM »
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.

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.
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades well ... there is now!"

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