Author Topic: Realistic, near-term, rotating Space Station  (Read 936590 times)

Offline HMXHMX

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Re: Realistic, near-term, rotating Space Station
« Reply #980 on: 07/18/2018 06:30 am »
I completely forgot that the poster was the guy. I'm stupid like that.

Odd choice of size. If you want to do human research (as well as animal), it seems odd to focus on a 1g station right out of the gate. It's the mid-g values that you want.
Page 11 shows where I began, i.e., a zero-g free flyer with the old NASA-NASDA 2.5 meter animal centrifuges.

I saw it in 2012. It was reassuring to know that other people actually want this research. I see so much resistance to it.

It was originally designed for Falcon Heavy, since at the time it was proposed, the New Glenn hadn't been unveiled.  But once it had, and given Bezos' preference for an O'Neill-type settlement vision (not to mention Elon told me studying this problem of reduced G survival wasn't a priority for him), I defaulted to NG once it became "available."

I wasn't playing favourites between the two. Musk, like most of the "Mars Underground", thinks that spin-g research is a waste, anything that gets between them and Mars is a waste. That doesn't mean he wouldn't happily launch any payload you care to pay him for.

OTOH, if you can get actual funding from Bezos, or even just free launches, Go For It.

The 1G level is designed an an on-orbit control

It's an argument I've had with Mike LePage before. I don't think that the first test facility needs to control for low-RPM 1g. Your first and most critical point of interest is whether the micro-g health issues go away with some gravity (and if so, how much.) Your control is ISS and Earth.

Sure, later on, you can pick a high-RPM tolerant crew and do 1g research, if there's weirdness in the results that bothers people. But why risk not even getting funded by having a shock factor like >100m length, for the very first thing you make? People know what the ISS costs, when you show an image of another facility on the scale of ISS and insist that it will be vastly cheaper, you'll have already lost your audience, even if you are right.

Indeed, that's why I'd prefer to start with a free-flying short-run very-high-RPM, low-g unmanned mouse & rat study. (I've suggested a Dragon capsule (just an example) so you can get the samples back.) It's a step up from the ISS mouse-centrifuge, hopefully doable within a Discovery-level budget. Once you pin down some values for mid-g health over a larger sample-size, that gives you some concrete values for a larger - but as small as possible - man-tended animal facility. Human results would be considered very preliminary, but between long-term animal and short-term human, that gives you values for how to keep a larger human-testing facility affordable. Or values that show the whole enterprise is pointless, if humans can't adapt to low-g, mammals can't breed in low-g.

Jumping straight to the end facility before you have reasonable numbers from the earlier ones, IMO invites early rejection from funders.

I'd expect a third flight at some future time to add an axial hub extension which would either allow another arm pair to be added or to provide more docking and zero-g working volume.

Careful. Axial masses reduce stability. You are probably already pushing it with the two capsules along the spin-axis.

(That's why I prefer to hang the solar arrays/radiators at 90° to the arms, increasing the distribution of mass in the plane of spin.)

Elon didn't lose his audience when he proposed building F1 and F9 for a few percent of NASA or conventional aerospace industry estimates.  And I firmly believe that a 1G facility makes everything (like ECLSS) easier, not harder.  And most of that "volume" is empty space.

My analogy for project size: you can ask an alumni donor for a new mass spectrometer or you can ask for a new engineering quad – the selling effort is pretty much the same, and the donor gets far more bragging rights for something significant like a building with their name on it.  We floated smaller projects and got zero traction.  Now, at least, we have some nibbles.

Offline blasphemer

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Re: Realistic, near-term, rotating Space Station
« Reply #981 on: 07/18/2018 07:15 am »
Sure, if we're limited to 1RPM and 1g we can still build giant cities in space... But we can't build small towns. And if you can't build a town, you sure as hell ain't building cities. There's no organic path forward. No steps.

High RPM could be a consideration for building little proof-of-concept test stations in near future. But small towns? Even a small town is at least several hundred meters long if you arrange it linearly, and that is down here on Earth. It will be even bigger in space, with all the support hardware and redundancy and actual incentive to build longitudally. I dare to say that any station in need of artificial gravity, meaning where people actually live their lives (as opposed to outpost being visited for a limited time like ISS), is half a kilometer minimum. We are not going to colonize space by counting every meter and every kilogram.
« Last Edit: 07/18/2018 07:35 am by blasphemer »

Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #982 on: 07/18/2018 11:28 am »
The 1G level is designed an an on-orbit control

It's an argument I've had with Mike LePage before. I don't think that the first test facility needs to control for low-RPM 1g. Your first and most critical point of interest is whether the micro-g health issues go away with some gravity (and if so, how much.) Your control is ISS and Earth.

Sure, later on, you can pick a high-RPM tolerant crew and do 1g research, if there's weirdness in the results that bothers people. But why risk not even getting funded by having a shock factor like >100m length, for the very first thing you make? People know what the ISS costs, when you show an image of another facility on the scale of ISS and insist that it will be vastly cheaper, you'll have already lost your audience, even if you are right.

Indeed, that's why I'd prefer to start with a free-flying short-run very-high-RPM, low-g unmanned mouse & rat study. (I've suggested a Dragon capsule (just an example) so you can get the samples back.) It's a step up from the ISS mouse-centrifuge, hopefully doable within a Discovery-level budget. Once you pin down some values for mid-g health over a larger sample-size, that gives you some concrete values for a larger - but as small as possible - man-tended animal facility. Human results would be considered very preliminary, but between long-term animal and short-term human, that gives you values for how to keep a larger human-testing facility affordable. Or values that show the whole enterprise is pointless, if humans can't adapt to low-g, mammals can't breed in low-g.

Jumping straight to the end facility before you have reasonable numbers from the earlier ones, IMO invites early rejection from funders.

Emphasis mine.

Just to repeat what I said at the time, the entire point of a control is that you won't know if there's weirdness in the results if you haven't done the control.  That's why you do the control. 

Also, because a man-tended rodent facility brings a whole new plethora of problems, I'm not yet convinced it's actually easier or cheaper than building a human scale centrifuge.

Those points aside, the reason I've moved my position on the 1G control issue is that I think your point on the $$ shock factor is valid, and I think we can do a separate experiment to control for spin rate if we build a transformable craft that is capable of testing the same G force at different spin rates (hence our Deployable Toroid Array design)... the key being that the experimental control for spin rate doesn't have to be done at 1G.

So the first experiment of interest to me (supposing our maximum r=20m, and that we can build a craft structurally capable of it):
1) we test subjects at Mars G and 4.2 rpm (r=20m),
2) we test subjects at Mars G and 6.7 rpm (r=7.8m),
3) we test subjects at Earth G and 6.7 rpm (r=20m).

I also think we'll want to do a series of experiments to probe what the threshold(s) of susceptibility to higher spin rates are, and particularly how quickly people can move from zero G to x rpm, which will be important for orbital spin gravity settlements.  So that might look like this:

4) we test subjects at Mars G and 4.2 rpm (r=20m),
5) we test subjects at Mars G and 5 rpm (r=14m),
6) we test subjects at 56% G and 5 rpm (r=20m).

7) we test subjects at Mars G and 4.2 rpm (r=20m),
8) we test subjects at Mars G and 5.8 rpm (r=10.5m),
9) we test subjects at 75% G and 5.8 rpm r=20m.

Making Mars G the control G level also means we build up a large amount of data at that acceleration level, which can't hurt Mars settlement efforts. 

Online Lampyridae

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Re: Realistic, near-term, rotating Space Station
« Reply #983 on: 07/18/2018 12:01 pm »
Adaptation seems to be long term; ie once you have been habituated to it, for at least 30 days there is a high level of retention.

Thanks for that. I hadn't realised the adaptation was retained that long.


{laughs} Yeah, good luck getting that past the ISS gatekeepers.

Yup. The CAM is (was?) sitting somewhere in Japan in a parking lot partly because of the effect of vibration on the rest of the station. Let alone a several tonne module spinning frantically whilst only centimetres from delicate hardware. But no-one will want to pony up money for a free-flyer for a while yet.

The smaller rodent centrifuges seem perfectly adequate for near-term data on centrifugation, although we'll have to wait a year or more before we get results for 1/6 and 1/3g.

Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #984 on: 07/18/2018 11:55 pm »
Just to repeat what I said at the time, the entire point of a control is that you won't know if there's weirdness in the results if you haven't done the control.  That's why you do the control.

And as I said, Earth is your control. (And ISS.) For the early testing, you aren't going to be seeing subtleties, at least amongst humans. Too few subject, too much variation in movement, activity, diet. You're only looking for the really big things. (And as I said more recently, the humans in an animal-tended facility aren't really there for human-health research. Sure, you'll do it, but you'll treat the results are extremely preliminary.)

By "weirdness", I meant that the results between 0 & 1g don't fit into a reasonable pattern. (Although I'm not, as I also said back then, expecting a single pattern for all health results. I suspect some will be resolved with minimal g-load, other will require nearly full 1g. The latter being the things that are most amenable to exercise. And some will be improved by >1g. I just read some JAXA research on their hyper-g mouse studies, apparently while muscle/bone/cardio health increases, fertility drops off a cliff. Sperm motility reduces rapidly. Meanwhile, their ISS research shows that in micro-g, sperm motility is higher than on Earth. But we also know that embryo development is often screwed up in micro-g. Everything's going to have its own health-curve.)

Also, because a man-tended rodent facility brings a whole new plethora of problems, I'm not yet convinced it's actually easier or cheaper than building a human scale centrifuge.

You think multi-generational studies on humans is easier than multi-generational studies on rodents? Remember the animal study gives you proper population sizes and lifetimes.

Offline QuantumG

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Re: Realistic, near-term, rotating Space Station
« Reply #985 on: 07/19/2018 01:30 am »
Why? If ya bother to read Globus you'll discover that space colonies are easier than ever, and with fully reusable super-heavy lift on the horizon, the only thing missing is the will to do it.

And the money and time (and technology) to build giga-ton sized habitats that won't kill their inhabitants when hit by space debris. Yeah, sure, near-term...  ;)

Giga-ton? Where does Globus talk about that?

Ironically, space debris wouldn't be a problem at all for a giga-ton sized habitat, whereas the smaller stations Globus is talking about would deal with debris much the same way as the ISS does (but more easily because they're stiffer than the ISS).

I simply must conclude that you haven't read anything he's written.
« Last Edit: 07/19/2018 08:35 pm by Lar »
Human spaceflight is basically just LARPing now.

Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #986 on: 07/19/2018 07:19 am »
Just to repeat what I said at the time, the entire point of a control is that you won't know if there's weirdness in the results if you haven't done the control.  That's why you do the control.

And as I said, Earth is your control. (And ISS.) For the early testing, you aren't going to be seeing subtleties, at least amongst humans. Too few subject, too much variation in movement, activity, diet. You're only looking for the really big things.

Why do you assume any effect would be small? 

The weirdness I'm talking about always, always comes out of left field.  You're expecting apples or oranges, or maybe a pear, and instead you get waffles.

Suppose for arguments sake, that spin rates above x rpm and y duration causes the development of Meniere's disease in a majority of people, independent of the subject's initial susceptibility to adaptation syndrome.  Pervasive symptoms completely wipe out the subject's ability to do useful work, but not immediately or evenly, and only a few months down the track.  Weirder things can and do happen all the time in research.

So, our chief investigator, who as with all inexperienced researchers, thinks he is saving the program time and money by skipping the 1G low spin-rate control in orbit.  He builds a gravity research facility in orbit that can test Lunar and Mars gravity at spin rates which are below the threshold for the disease.

So at this point, the investigator has spent a decent chunk of what he would have spent anyway had he done the control - and he gets two data sets of data points (Gary, I hope you don't mind my repurposing your graphs).



Woohoo! Even though there is a spread of symptoms, and some are on the low side of linear, most are better.  And Mars gravity is even better than lunar gravity.  So he applies for and receives the next round of funding to fill in the curve.



Meniere's symptoms are starting to appear, affecting all the other health measures, but as with all such diseases, they're difficult to separate out from all the other data.  "That's weird", he says, trying to imagine how the curve will join up with his asymptomatic controls on the ground, and maybe for the first time questioning his assumption that spin gravity at 1G would be the the same as Earth surface gravity. 

He applies for more money, because he needs to check his original assumption.



What the hell? How can subjects be worse than zero-G? At last the full impact of Meniere's diseases rears it's head, and our chief investigator is, justifiably, fired, because the program now is either cancelled, or has to foot the bill for the design and construction of a whole new gravity facility, so they can do the spin-rate control that they should have done in the first place.

Maybe you think I'm being a little over the top, but seriously this stuff writes itself because of how often stuff like this happens.

Offline Roy_H

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Re: Realistic, near-term, rotating Space Station
« Reply #987 on: 07/19/2018 04:55 pm »
You guys are quite right in my design I make a gross assumption that there will be no problems with 2 RPM and people working half a day and 1g environment and half a day and 0g. This should be proven out first at a smaller scale.

Last pic shows elevator docked at rim.
« Last Edit: 07/19/2018 05:21 pm by Roy_H »
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Offline Roy_H

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Re: Realistic, near-term, rotating Space Station
« Reply #988 on: 07/19/2018 05:18 pm »
Just for clarification, the hub modules are primarily BA2100s, some modified for ports on the side. The rim modules are not BA330s but a new purpose built design I call BA1400. They are 18m long 12m diameter and have three levels in them, top floor is for state rooms and lower level is for utilities.
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Offline Paul451

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Re: Realistic, near-term, rotating Space Station
« Reply #989 on: 07/19/2018 06:56 pm »
thinks he is saving the program time and money by skipping the 1G low spin-rate control in orbit.

Define "low spin-rate". Is it 1RPM? Or 2? Even 4? But definitely not 5 or 6? Show me the prior science that tells you the known safe spin-rate?

You are still making an huge, untested assumption, only you are refusing to see it as an assumption.

And the difference in scale between 1-6RPM is 36-fold, between 1800m and just 50m, so you are always going to try to argue that at least 4RPM is "low", and your opponents/critics are always going to argue that 4RPM is much too high as a "control".

Even at 1RPM, you could build a trillion dollar, 1.8km station, with 1000 people living on board as your sample, and still get the same weird result as in your scenario. That's why you start as small as possible. Building a big expensive thing without having tested the basic concept on a smaller scale strikes me as deeply unrealistic.

Finding that there's a completely unexpected inner-ear disease caused by >6RPM but not 4RPM would be an extraordinary result, especially from such a tiny sample size. Why would someone lose their job over that? That's exactly what an experimental station is meant to find. The researchers would be waving in the faces of their critics.

Offline Jim

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Re: Realistic, near-term, rotating Space Station
« Reply #990 on: 07/19/2018 07:26 pm »
You guys are quite right in my design I make a gross assumption that there will be no problems with 2 RPM and people working half a day and 1g environment and half a day and 0g. This should be proven out first at a smaller scale

There is no reason to use inflatables or expandable modules for such a station. 

Offline Eric Hedman

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Re: Realistic, near-term, rotating Space Station
« Reply #991 on: 07/19/2018 08:01 pm »
In reading some of the posts I see some complex ideas that would take quite a while to do.  For the subject matter of the thread "near-term", how many years out is "near-term"?

Offline Roy_H

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Re: Realistic, near-term, rotating Space Station
« Reply #992 on: 07/19/2018 08:30 pm »
But I meant by near term is 10 - 20 years. My main point is that it could be built with technology that is either available now or expected be available soon.
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Offline Eric Hedman

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Re: Realistic, near-term, rotating Space Station
« Reply #993 on: 07/19/2018 09:02 pm »
But I meant by near term is 10 - 20 years. My main point is that it could be built with technology that is either available now or expected be available soon.
Given that time frame let's say around 2030 to start launching and 2035-2040 to complete, the launchers available hopefully at a minimum would be BFS/BFR, Vulcan with ACES, New Glenn and possibly New Armstrong.  Hopefully SLS will be retired.  The next generation of life support will have been tested out on ISS and on LOP-G if it gets built.  Launch costs should hopefully continue to fall.  There will be more standards for connecting modules for things like power distribution, fluid connections, etc.  Aerospace companies will have improved more flexible manufacturing techniques for station modules.  I wouldn't expect any massive stations with crews in the hundreds in orbit by then.  But doing something like this may be come noticeably more affordable.  The interesting thing will still be if a business case develops for doing this.

Offline Roy_H

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Re: Realistic, near-term, rotating Space Station
« Reply #994 on: 07/20/2018 04:03 am »
To be economically viable there probably has to be an anchor tenant, like in large shopping malls. I think this means it there must be something that can only be manufactured in space and not down on earth that can generate large profits. Maybe in the pharmaceutical industry. Research is a natural and other possibilities would be a Hollywood style studio for sci-fi movies and of course tourists.

I always imagined the space station would be a jumping off point for human a deep space exploration, but all plans to date bypass the ISS. Is this really the best approach?
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Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #995 on: 07/20/2018 04:34 am »
To be economically viable there probably has to be an anchor tenant, like in large shopping malls.

Certainly our only multi-national space station pretty much used that method, with the U.S. being the anchor tenant. And I'm sure whoever owns the stations would prefer to have anchor tenants, and not have to piecemeal renting/leasing out the space.

Quote
I think this means it there must be something that can only be manufactured in space and not down on earth that can generate large profits. Maybe in the pharmaceutical industry.

Certainly one possibility, and I just want to point out that any such manufacturing would not have to take place on the artificial gravity station. The station could just be the place where the factory workers live while they make "stuff" in zero-G.

Being a bunkhouse or hotel, or really a place of health refuge, would be a good use of artificial gravity stations.

Quote
Research is a natural...

It is, but I think the type of customers is probably limited - and the demand for artificial gravity probably limited too.

Quote
...and other possibilities would be a Hollywood style studio for sci-fi movies and of course tourists.

Did you see the movie "Gravity"? It had a $100M budget, but I'm sure only a fraction of that was needed to simulate zero-G effects. And overall this type of work is pretty spotty and unpredictable, so it would be tough to justify the construction of an artificial gravity station partially on the potential demand for entertainment uses.

Quote
I always imagined the space station would be a jumping off point for human a deep space exploration, but all plans to date bypass the ISS. Is this really the best approach?

I don't know if there was a serious plan to use the ISS as a jumping off point. And it certainly is not designed to support that.

I would imagine most traffic to BLEO destinations would prefer to get to their destination as soon as possible, so other than waiting at an LEO transportation hub, they would want to be in transit that stopping along the way.

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

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Re: Realistic, near-term, rotating Space Station
« Reply #996 on: 07/20/2018 06:48 am »
thinks he is saving the program time and money by skipping the 1G low spin-rate control in orbit.

Define "low spin-rate". Is it 1RPM? Or 2? Even 4? But definitely not 5 or 6? Show me the prior science that tells you the known safe spin-rate?

You are still making an huge, untested assumption, only you are refusing to see it as an assumption.

And the difference in scale between 1-6RPM is 36-fold, between 1800m and just 50m, so you are always going to try to argue that at least 4RPM is "low", and your opponents/critics are always going to argue that 4RPM is much too high as a "control".

Even at 1RPM, you could build a trillion dollar, 1.8km station, with 1000 people living on board as your sample, and still get the same weird result as in your scenario. That's why you start as small as possible. Building a big expensive thing without having tested the basic concept on a smaller scale strikes me as deeply unrealistic.

Finding that there's a completely unexpected inner-ear disease caused by >6RPM but not 4RPM would be an extraordinary result, especially from such a tiny sample size. Why would someone lose their job over that? That's exactly what an experimental station is meant to find. The researchers would be waving in the faces of their critics.

My mistake, I shouldn't have included the word "low" in that sentence - it should have been "1G spin rate control".

Whether or not "low spin-rate" is defined as less than 1, 2, 4, 6 or 10rpm, is completely separate from the point I am making.  The fact I think the adaptation threshold might be lower than you do is yes, an assumption, but also completely irrelevant to what the best approach to finding out what the answer actually is.

The story in my post above was an attempt to illustrate why your approach to answering the question is conceptually flawed, simply by not doing the appropriate controls first.

Centrifugal acceleration is achieved by a qualitatively different mechanism to acceleration due to linear gravity.  Subjects in linear gravity on Earth (or Mars or the Moon for that matter) are not acceptable controls for subjects in a centrifuge.  It is only once we understand how data from subjects in centrifuges compare to data from subjects in linear gravity, that we can make informed comparisons between 1G (Earth surface) and partial G (centrifuge).

So as I said in the post before that, the control we need to do first is to test the same g-level at different spin rates, to isolate the effect of spin rate from gravity level.  Ideally, that g-level would be 1G, but as you've rightly pointed out multiple times now, a 1G spin rate control experiment is likely to be expensive to implement, especially when "low spin-rate" is still badly defined. 

The alternative, less-than-ideal but still super important to do first control, would be to test a lower g-level at multiple spin rates, and that's why I suggested Mars G (at 4.2rpm vs 6.7rpm) etc.  You don't skip the control just because one implementation of that control would be expensive, you figure out a cheaper way to do the control.

Offline Asteroza

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Re: Realistic, near-term, rotating Space Station
« Reply #997 on: 07/20/2018 08:36 am »
To be economically viable there probably has to be an anchor tenant, like in large shopping malls. I think this means it there must be something that can only be manufactured in space and not down on earth that can generate large profits. Maybe in the pharmaceutical industry. Research is a natural and other possibilities would be a Hollywood style studio for sci-fi movies and of course tourists.

ZBLAN fiber optic manufacturing looks to be viable right now but that's zero-g manufacturing, which may also require low vibration.

Which suggests a free flyer. So man tended freeflyer fleet and attendant spun astronaut shack with suitcraft/tug interaction would be one scenario. Whether one could achieve something similar with an appropriate despun core/backbone and modules suspended/anchored via cable tension (thus can supply power and cooling to an otherwise isolated man tended module)(worst case magnetic module mounts and loose cables) would be another scenario.

Though the general implication is a space industry prefers zero-g, thus many possible anchor customers are not compatible with a 1G/variable-G station directly. The only industry that gains from variable-g would be specialized manufacturing that needs variable-g or high-g. Think weird separation/solidification, or fancypants single crystal metal manufacturing that one might try to do in centrifuges on earth. Very high G is easier in space, if you had a bolo or tether type station, as you just need more radius length.

Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #998 on: 07/20/2018 08:48 am »
But I meant by near term is 10 - 20 years. My main point is that it could be built with technology that is either available now or expected be available soon.
Given that time frame let's say around 2030 to start launching and 2035-2040 to complete, the launchers available hopefully at a minimum would be BFS/BFR, Vulcan with ACES, New Glenn and possibly New Armstrong. 

To be economically viable there probably has to be an anchor tenant, like in large shopping malls. I think this means it there must be something that can only be manufactured in space and not down on earth that can generate large profits. Maybe in the pharmaceutical industry. Research is a natural and other possibilities would be a Hollywood style studio for sci-fi movies and of course tourists.

I always imagined the space station would be a jumping off point for human a deep space exploration, but all plans to date bypass the ISS. Is this really the best approach?

Probably the reason this thread has had such longevity is the heated discussions had over what, precisely, this station is actually for, and I think the variety of launch vehicles and the expected frequency of launch gives us a good clue.

If you can put lots of people in orbit for the 45 minutes it takes to go halfway around the world (BFR Earth-to-Earth), then the only thing that stops you from keeping them in orbit for a week or two is dedicated facilities, with basic levels of comfort.  People will want to eat/drink/go to the bathroom in partial G, and play in zero-G.

I really think the killer app for these facilities is space tourism.  If your trip can be subsidised by participating in or performing science experiments, all the better.  What manufacturing works best is something we might have ideas about now, but is only something people will figure out once they're up there.

Offline Roy_H

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Re: Realistic, near-term, rotating Space Station
« Reply #999 on: 07/20/2018 01:52 pm »
@Asteroza I was a little confused to by your description especially the reference to despun. Attached is my full description.
"If we don't achieve re-usability, I will consider SpaceX to be a failure." - Elon Musk
Spacestation proposal: https://politicalsolutions.ca/forum/index.php?topic=3.0

 

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