Author Topic: Realistic, near-term, rotating Space Station  (Read 446564 times)

Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1780 on: 09/08/2022 09:46 pm »

The cost of a rotating space station that provides 1G is likely to be far more than just the 3X factor of provided gravity ...

There is no information given above which would support the suggestion that the direct cost of a ring station is completely dependent on its multiple of gravity.

I wasn't referencing anything "above" for my guestimate.

I've done designs for Mars-level gravity and Earth-gravity rotating space stations, and Earth-level gravity stations are going to be HUGE. And the more mass you have along the circumference for the station, the more structural mass you need to hold the whole thing together.

Think of it this way. A 0G space station doesn't require much structural mass to hold all the modules together. Once you start spinning a station, it requires more and more structural mass to resist the centripetal force that wants to separate the rotating space station. So the more gravity the station simulates, the higher percentage of the structural mass vs living space.

I think humanity will be capable of building Earth-gravity rotating space stations, but not for many years/decades. I think we will have to progressively build up to that size, since controlling anything big that holds humans while spinning in space is still something humans don't know how to do.

So without knowing what the business models are for them, I think this is the order that we'll build rotating space stations:

1. Rotating space station testbeds that are used to investigate and validate spin gravity and its uses.

2. A Mars-level rotating space station that will be used as a refuge (or long-term housing) for humans involved with space exploitation far from Earth.

3. A human colony in space that uses something above Mars-level gravity, but maybe less than Earth-level.

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 mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1781 on: 09/09/2022 06:25 am »
Extreme hypothesising here. We are now entering the Twilight Zone.

Interesting links, but hard to see hospitals transporting already sick patients into orbit anytime soon. What I think will be interesting however is the results of large-scale population studies over time on the occurrence of various conditions. I can imagine there being some population study in the future that analyses the results of say 100,000 person-days in space - and finds that the odds ratio of getting *xyz* disease in space is reduced, and then in-space treatments/gravity level accommodation may be prescribed to pre-emptively treat that disease.     

...Earth-level gravity stations are going to be HUGE. And the more mass you have along the circumference for the station, the more structural mass you need to hold the whole thing together.

The problem is analogous to the tyranny of the rocket equation. Fortunately we don't have to start with the gigantic structures in order for spin-G to be useful. Even for human-scale space stations, it's reasonable to assume that lunar and Mars G space stations will serve as scaffolding for the construction of larger scale space stations.

Somewhat off topic, but one of my favourite long-term concepts to get to kilometre scale settlements involves going full biomimicry and constructing a structural framework of cells (made of some combination of locally-sourced regolith, binding agent, and high strength cable)  each containing an inflatable habitat module. You build this in the shape of a nautilus/snail shell, with its diameter growing logarithmically by some small multiplier with each revolution. Partly I just like this as a model for an ongoing toroidal space settlement that is always in the process of renewing itself, recycling material from the innermost & oldest layer, and building anew on the outermost layer. The idea would be to actually inhabit the station for the entire construction phase, with the size of the settlement only maxing out once the (probably asteroid) local resource is consumed, which is a hundred year project or more.



Offline Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #1782 on: 09/09/2022 12:39 pm »
Slightly OT, a structural strength analysis of a 0.38g cavern inside a rocky asteroid.

https://www.frontiersin.org/articles/10.3389/fspas.2019.00037/full

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1783 on: 09/09/2022 01:11 pm »

I wasn't referencing anything "above" for my guestimate.

My $0.02

Huh.  So if we build a ring station for lunar gravity it will cost six times less?

Good to know.
Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1784 on: 09/09/2022 01:17 pm »

You build this in the shape of a nautilus/snail shell, with its diameter growing logarithmically by some small multiplier with each revolution.

Draw a picture.  I'm not visualizing it beyond the nautilus shape.

Your idea about "growing" the station is something that I've thought about.

The 1000yard radius ring station becomes the first section of an O'Neill structure, as the station is expanded along its axis of rotattion.

Sometimes I just flat out don't get it.

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1785 on: 09/09/2022 01:35 pm »
Slightly OT, a structural strength analysis of a 0.38g cavern inside a rocky asteroid.

Hah.   Thanks 4 the math!

From:

https://www.frontiersin.org/articles/10.3389/fspas.2019.00037/full

Quote
Considering a size range of rc = 50Ö250 m for example, the rotation rates would need to be between 1.17 and 2.6 rpm (rotations per minute) to create artificial gravity necessary for sustaining extended stays on the station (assuming 0.38 gE as discussed above). Figure 2 gives an overview of rotation rates for a range of radii and gravity levels. The area usable for a space station subject to artificial gravity is the lateral surface of the cylinder S...

They'd have to be pretty darn sure the asteroid can rotate that fast without ripping itself apart, which they specifically acknowledge:

Quote
Imposing a spin rate sufficient for providing artificial gravity on the lateral surface of the cylinder will create a substantial load on the asteroid material due to centrifugal forces. While little is known on material properties of small asteroids subject to our study, we rely on assumed material strength.

Their picture of Vesta does not agree with the proportions of Vesta as shown by the oracle.  The asteroid is not as slender as they illustrate.  They go on to suggest a couple of candidate asteroids:

Quote
We will apply the analytic models 1 and 2 to a rocky asteroid with dimensions 500 ◊ 390 m. There is a number of similar-sized rocky near-Earth asteroids, e.g., 3757 Anagolay, 99942 Apophis, 3361 Orpheus, 308635 (2005 YU55), 419624 (SO16), etc. (cf. JPL, 2018). As little is known about the composition and material properties of these objects, we assume they are composed of basaltic rock with a bulk density of ρ = 2.7 g cm−3.

My sense is that it is easier to build a multiple launch, in orbit assembly ring station than it is to buid an excavated multiple launch, in orbit assembly tube station of the same gravity of 0.38 gee.
Sometimes I just flat out don't get it.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1786 on: 09/09/2022 02:16 pm »

Draw a picture.  I'm not visualizing it beyond the nautilus shape.

Your idea about "growing" the station is something that I've thought about.

Go you one better. I was part of team in 2016 that submitted a similar concept at a NASA weekend hackathon. Itís actually how I met my co-founder Carl.

« Last Edit: 09/10/2022 02:03 am by mikelepage »

Offline MGoDuPage

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Re: Realistic, near-term, rotating Space Station
« Reply #1787 on: 09/20/2022 07:21 pm »

I'm beaten with canes every time I suggest it, but I think for a while the expedient solution will be at most a centrifuge gym for the humans to work out in, so that their health doesn't degrade as much, and I think that will remain the case up to stations supporting even 10s or hundreds of people.

I haven't done any reading on the effects of gravity on the human body during exercise vs. rest, but why would a small centrifuge/AG system dedicated specifically to a gymnasium be the best way to combat the effects of microgravity? If most folks are getting ~6-8 hours of sleep per 24 hour period, wouldn't it be more beneficial for their bodies to experience 1g for ~8 hours per day (even if resting) vs. 1-2 hours per day during a workout?

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #1788 on: 09/21/2022 02:21 am »
If most folks are getting ~6-8 hours of sleep per 24 hour period, wouldn't it be more beneficial for their bodies to experience 1g for ~8 hours per day (even if resting) vs. 1-2 hours per day during a workout?

Gravity has virtually no beneficial effects on the body during sleep. (Or laying down in general.)

To the point where bed-rest studies are used as a proxy from zero-gravity for Earth-based health research.

OTOH, high impact exercise is the perfect time to add gravity. High heart-load, highly variable vascular pressure in the lower body, joint/bone impact/shock, etc etc.

But is 1-2hrs enough to offset the rest of the day? We don't know. Brand new science. 60 years in space, and we still don't have good data. Even from animal studies.
« Last Edit: 09/21/2022 02:22 am by Paul451 »
Huh. Ironically, the aim of utilising cheap-launch is to make launch costs significant again.

Offline Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #1789 on: 09/21/2022 10:42 am »
If most folks are getting ~6-8 hours of sleep per 24 hour period, wouldn't it be more beneficial for their bodies to experience 1g for ~8 hours per day (even if resting) vs. 1-2 hours per day during a workout?

Gravity has virtually no beneficial effects on the body during sleep. (Or laying down in general.)

To the point where bed-rest studies are used as a proxy from zero-gravity for Earth-based health research.

OTOH, high impact exercise is the perfect time to add gravity. High heart-load, highly variable vascular pressure in the lower body, joint/bone impact/shock, etc etc.

But is 1-2hrs enough to offset the rest of the day? We don't know. Brand new science. 60 years in space, and we still don't have good data. Even from animal studies.

There are molecular and genetic microgravity effects which bed rest doesn't approximate. Some effects occur on the timescale of minutes, others hours, days or weeks. So gravity is still important during sleep.

Offline Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #1790 on: 09/21/2022 10:48 am »
But first, this is a roundabout answer to your question, but there was one talk at ISSRDC that was pretty impactful for me (re the market for in-space production applications). This was a report on the liver "organoid" work being done on station. (Organoids are described as little balls of tissue grown in zero-g on 3d printed scaffolding with patient-derived stem cells - there are a number of reasons this works better in zero-g).

Came across this and thought it would be useful for you:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8758939/

Offline Twark_Main

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Re: Realistic, near-term, rotating Space Station
« Reply #1791 on: 09/27/2022 12:40 am »
You also didn't articulate any technical criticisms, beyond "the thing you said is wrong because I say so."  :-\

Both of us can "say so" just fine. It's the engineering argument behind it that counts.
<snip>
Arguments by Adage are cool, but technical points of disagreement are what I'm really looking for. If I'm wrong, fine. I'm wrong a lot! Just tell me why.

But there's no real "engineering argument" to be had yet... unless I've missed something, we're both looking at the hand-drawn sketch, right?  I have artist friends who could have come up with something similar in under ten minutes

But your friend didnt come up with it in ten minutes. Vast commissioned it. So I'm going to assume it reflects what Vast wants to do, and doesn't reflect what they don't want to do.

Crazy right?



My two cents [...]: What is actually needed, is to optimise for usable volume (at a given gravity level) per moment of inertia unit (kg.m2)...

The Vast design requires multiple launches and ISS-level in orbit-assembly, for a design that wastes a lot of internal volume for the amount of mass it needs. The large moment of inertia precludes starting and stopping it frequently, so you'll have to choose between even more complex docking systems, or adding to the already difficult scheduling issues currently seen at ISS. They've decided to start with a human-scale space station design, apparently ignoring the long history of similar failed projects, and are competing with other, well-resourced human-scale CLDs, who have rightly identified that the market for large amounts of volume in space is mainly zero-G for foreseeable future.  Sure, you might want to do multiple levels of G simultaneously in some experiments initially, but since zero G will always be a simpler proposition, the experiments will mostly be 3-way comparisons between 0xG, XxG and 1xG, so an already wasteful design will become even more wasteful over time.

Baton stations imo are most useful in the context of interplanetary trajectories, where you have long cruise phases between thrust phases or other interactions that necessitate spin/despin maneuvers, and you want a robust structure that can take somewhat high g-force burns. Again, I wish them luck, but like I say, I hope their shareholders have open minds and are in it for the long haul, because history is not on their side.

I'll reply over in the appropriate thread.

Needless to say, I think you're focusing on the downsides and taking a negative attitude without proposing a cohesive design that's actually superior. If you focus only on the flip side of every technical trade-off made in a complex design then you can make literally anything look bad.
« Last Edit: 09/27/2022 12:41 am by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline Twark_Main

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Re: Realistic, near-term, rotating Space Station
« Reply #1792 on: 09/27/2022 12:46 am »
Pretty sure nobody's "mad".

You also didn't articulate any technical criticisms, beyond "the thing you said is wrong because I say so." 
Um.  Am I supposed to be "mad" about that?

Your choice. My point is that nobody should to be convinced by your non-argument.
« Last Edit: 09/27/2022 01:00 am by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline Twark_Main

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Re: Realistic, near-term, rotating Space Station
« Reply #1793 on: 09/27/2022 12:51 am »
What I want to see built is roughly...

Ahh yes, the start of any successful Requirements Document: arbitrarily pulling numbers out of thin air.  :-\
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1794 on: 09/27/2022 12:56 pm »
What I want to see built is roughly...

Ahh yes, the start of any successful Requirements Document: arbitrarily pulling numbers out of thin air.  :-\

Like JFK's "We Choose the Moon" speech.

Show me the beginning of any "Requirements Document".
Sometimes I just flat out don't get it.

Offline DanClemmensen

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Re: Realistic, near-term, rotating Space Station
« Reply #1795 on: 09/27/2022 03:42 pm »
What I want to see built is roughly...

Ahh yes, the start of any successful Requirements Document: arbitrarily pulling numbers out of thin air.  :-\

Like JFK's "We Choose the Moon" speech.

Show me the beginning of any "Requirements Document".
The requirements specification is not the start of any development process I have ever seen. The requirements spec responds to a higher-level input. In the business world it's often a "business case", which itself has multiple inputs. for new starts, it's often the entrepreneur's vision, usually formalized into a goal. For Apollo, "We Choose the Moon" was the input to the requirements specification.  And of course it's often a "waterfall" model, so development of the requirements uncovers things that are fed back upstream to cause refinements to the goal or vision. Details vary wildly, but you don't start with requirements.

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1796 on: 09/27/2022 07:13 pm »
You don't start with requirements.

The semantic gymnastics around here offer a partial explanation of why NASA has had a hard time moving forward on HSF.  The main "requirement" of "we will land a man on the Moon" is, well, landing a man on the Moon.
Sometimes I just flat out don't get it.

Offline mikelepage

Re: Realistic, near-term, rotating Space Station
« Reply #1797 on: 09/28/2022 09:09 am »
Arguments by Adage are cool, but technical points of disagreement are what I'm really looking for. If I'm wrong, fine. I'm wrong a lot! Just tell me why.
<snip>
Needless to say, I think you're focusing on the downsides and taking a negative attitude without proposing a cohesive design that's actually superior. If you focus only on the flip side of every technical trade-off made in a complex design then you can make literally anything look bad.

You literally asked for technical points of disagreement, which I gave, then you said I was being too negative.  ;D

As I said previously, I wish them well, but I think it's a brute force approach. Maybe starship launch prices, plus the right investors, will mean that this is an approach whose time has come.

I'm sorry I can't say more about our plans - I will put a link here when we go public. For now, I've identified both 1) what we think the target market is: existing users of in-space production applications (INSPA) represent industries worth $100+B per year (i.e. these are users of the ISS National lab/CLDs who value the microgravity environment, but have handling issues where sporadic spin gravity will help), and also 2) the thing I think needs to be optimised: usable volume (at a given gravity level) per moment of inertia unit (kg.m2).

Offline JohnFornaro

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Re: Realistic, near-term, rotating Space Station
« Reply #1798 on: 09/28/2022 12:45 pm »
And, just for the record, I'm changing my mind.  In the case of a 1K yard rotating station at 1 rpm with 1 gee at the rim, the hub should be fixed. The low constant rate of rotation will not be disorienting to the human crew of an approaching craft.
Sometimes I just flat out don't get it.

Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1799 on: 09/28/2022 02:54 pm »
And, just for the record, I'm changing my mind.  In the case of a 1K yard rotating station at 1 rpm with 1 gee at the rim, the hub should be fixed. The low constant rate of rotation will not be disorienting to the human crew of an approaching craft.

Was that the only reason why you were doing it? Because why would you assume that humans are going to be piloting spacecraft in space like old time bush pilots?

To me, the major reason to have a stationary docking point is because that way you don't have to worry about making the spacecraft rotate. Weight and balance of a rotating spacecraft is going to be a challenge that humans won't be able to manage, and even computers will have a challenge with. Best to NOT rotate the spacecraft, and have them dock at a non-rotating docking point.
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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