Realistic, near-term, rotating Space Station

[Coastal Ron]

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

I just want to remind everyone that factory workers DON'T live at factories here on Earth. They live in residential communities.

So of course our future can have zero-G factories that require humans, and the humans will be living in (hopefully) artificial gravity residential stations. And they will commute between the two.

Also, we are far away from being able to have factories that rely on autonomous robot workers, or even remotely controlled robotic systems. So human workers will still be necessary at space factories, especially to set them up.

Which means if you identify demand for zero-G manufacturing, you'll automatically identify demand for artificial gravity stations for the workers to live on.

[bad_astra]

The only use I can see for partial-g rotation is as a test of low-g human health.
However the moon is much closer and doesn't need to be engineered for rotation.
It may be a fact of life for both future Lunar people and Martian settlers that to keep their bodies viable for a return to earth, they may have to spend at least a certain amount of time in 1g. The same goes for persons wanting go have children.
That may require a trip to earth (if you're at the Moon) or if you're further out, a rotation station, which would essentially be a vacation, health spa, and fertility clinic all rolled into one.

Because of that I don't think there is a near term need for rotation right now. Until we're ready to build truly large 1g colonies, I just don't see the point.

[Paul451]

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? [...] You are still making an huge, untested assumption

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.

Actually that was the point I was making. The RPM is irrelevant to the example you raise. The same potential unknowns could occur at any scale, at any spin. That problem doesn't tell you anything about the validity of the lower-RPM/lower-g data.

Let me use an real example: The JAXA mouse-centrifuge on ISS. They are doing exactly what you want. Their first run is 1g, with mid-g runs delayed for a couple of frustrating years. They even have a non-rotating 0g control in the same CBEF unit.

So this serves as a 1g control, right? Except the 1g run will be at a much higher RPM than a lower-g run (77RPM vs say 47 for Mars-g). They can't control for spin rate independently of g-load. You can't compare the 1g data against the lower-g data at the same spin-rate. Throw in the fact that the radius is so short that the g-load across the height of the cage varies by half a g, thus depends on how much climbing the mice do. In effect, the only thing they are controlling for, is the facility itself (noise/vibration/air/etc). Yet no-one seems to consider the experiment worthless.

Let's say that the 1g, 77RPM run produced its data and found that there were behavioural changes in the mice, suggesting inner-ear issues. Do you think they'd throw out all the other data from muscle/bone/heart/kidney results because of that? Or remove the facility without doing lower-g runs?

Another example is ISS itself. What is the "control" to separate genuine micro-g effects from the effects of station air-quality or radiation or other quirks of ISS? You live with the ambiguity because it's all we have.

The only thing I'm saying for a modest spin-g human-tended facility is that you start at low-g to prove the facility functions, to prove that humans can handle each spin-rate for months at a time. During that incremental spin-up, you might as well gather whatever biological data you can.

Eventually, IFF the facility and the crew can handle it, THENN you might bring it up to 1g. Or even a little higher. Otherwise you live with what you can get.

Similarly, as I've said several times, the data for humans won't be clean. Too small a sample size, and too noisy because (amongst other things) they are moving between g-levels when tending animals and fixing equipment, and the fact that the crew aren't randomly selected typical examples. You're selecting them because they pass spin-dizziness tests on the ground. But do you think anyone will reject the only data we have for 0<g<1? You live with what you can get.

If you fixate on 1g, you might end up never getting funding. If you fixate on low-RPM, you almost won't get funding.

Hey, if someone like Bezos starts handing out billions for Ron_H's station, great, go nuts. But unless that happens, you live with what you can get.


[We're not going to agree on this. So for the sake of the thread, after you reply, how about we let it go for another six months?]

[Paul451]

The only use I can see for partial-g rotation is as a test of low-g human health.
However the moon is much closer

You think the moon is closer than LEO?

The cost of building a small test facility in LEO is much less than building a moon base. Let alone a Mars colony.

So shouldn't we learn if, for example, humans can actually handle long term Mars-g before we send humans?

and fertility clinic all rolled into one.

Judging by mice experiments, you might be more fertile in low-g. The issue is probably embryo development. And we don't have any data on how much gravity embryos need to develop properly. Gee, if only we had a facility to test in.

[bad_astra]

The only use I can see for partial-g rotation is as a test of low-g human health.
However the moon is much closer

You think the moon is closer than LEO?

The cost of building a small test facility in LEO is much less than building a moon base. Let alone a Mars colony.

So shouldn't we learn if, for example, humans can actually handle long term Mars-g before we send humans?

and fertility clinic all rolled into one.

Judging by mice experiments, you might be more fertile in low-g. The issue is probably embryo development. And we don't have any data on how much gravity embryos need to develop properly. Gee, if only we had a facility to test in.

Closer to realization yes. I should have clarified that.

Building a moon base and maintaining it long enough to understand the effects of partial g on life would benefit form en-situ resources. Any realistic near-term rotating station that could be built now isn't going to address much of that properly as it will have a very limited amount of test data, whereas we could have thousands of people living and working on the moon if there was an effort of will for it, in a couple of decades.  I suspect the main problem with pregnancy in partial g might be ectopic pregnancies, as well as abnormal development of the fetus. This is going to bring up a lot of reproductive rights issues that are beyond the scope of this thread, but i do think it gives a good reason long term for some sort of 1g rotation station.

[mikelepage]

Let me use an real example: The JAXA mouse-centrifuge on ISS. They are doing exactly what you want. Their first run is 1g, with mid-g runs delayed for a couple of frustrating years. They even have a non-rotating 0g control in the same CBEF unit.

Yep, scientists with constrained budgets breed frustration.  Doesn't make their approach any less valid. 

Hey, if someone like Bezos starts handing out billions for Ron_H's station, great, go nuts. But unless that happens, you live with what you can get.

[We're not going to agree on this. So for the sake of the thread, after you reply, how about we let it go for another six months?]

Agreed, although I do think it is important that anyone interested in spin G see this debate play out every so often (and fwiw, no hard feelings on my part).  Debates of proper scientific procedure versus economic expediency is always worth having in my opinion.

The fact is that whoever actually figures out how to put together the money to make it happen will be the one who decides how it should happen.  Hopefully by the next time we come back to this we'll have something more concrete to discuss.

[LMT]

The fact is that whoever actually figures out how to put together the money to make it happen will be the one who decides how it should happen.

And SpaceX could have both money and motive near-term.

To blaze the trail to Mars they need data to set appropriate flight g and Mars gym g.  Using 1-, 2- and 4-ITS test systems they could collect big data on most any 0-1 g scenario.  That much they could accomplish, and promptly, in LEO; beginning even circa 2022.

When tests are done, the test systems may be repurposed for revenue etc.

We see AG dollar amounts in forum, some scary-sounding, but ITS mods seem small enough to fit within plausible ITS budget.  For example, the following "safety features":

- vertical integration points could be upgraded if necessary for wet mass, to handle certain pad-abort scenarios.  Crane-lift of an ITS craft's wet mass would be an abort option.

- a simple but robust propellant line-and-connector upgrade could manage unexpected forces during propellant transfer.

- a free-flying inspection camera could be carried aboard test flights.  It would survey the spacecraft exterior for issues, propelling itself via some safe method, such as water resistojet.

--

All for safety, right?

And all within plausible ITS budget.

Needles, haystack, some assembly required.

[music]

--

Of course, Elon says he's not interested in AG.  And that's all we know. 

Well, not all we know. 

We also know execs only leave fake plans on the photocopier. 

[Coastal Ron]

The cost of building a small test facility in LEO is much less than building a moon base. Let alone a Mars colony.

Could be. Colonizing will be expensive, no doubt about that.

So shouldn't we learn if, for example, humans can actually handle long term Mars-g before we send humans?

No, because what is the different between humans experiencing 1/3 G on Mars and humans experiencing 1/3 G on an artificial gravity research station?

People on Mars will be more active and likely have a more valid set of experiences to answer the question of whether living in 1/3 G is detrimental to humans. And that activity could be important in being able to acclimate to low gravity environments.

So why have low gravity artificial space stations?

Because our Moon and Mars are not the only locations humanity will be expanding out into. If we want to travel through space for long periods of time, like around our solar system, then we need to find out what is the minimum or acceptable amount of gravity that we need to provide, because more gravity means more mass, and more mass is more fuel and money.

Plus, when people do go to planets with less than 1 G of gravity, artificial gravity stations could be places of medical refuge around those planets, but we'll want to know how much gravity we need to provide for that purpose.

So the bottom line is that we should make artificial gravity research a priority in order to support the expansion of humanity out into space, but we don't need to use artificial gravity as a gating item for exploring our Moon or Mars.

[punder]

Probably been said many times already, but at this point, if you give any credence to EM's ambitions, people will be living and working in 1/6 and 1/3 g long before any rotating hab could possibly be in operation. Especially given NASA's long-established institutional opposition--they're all about microgravity, viewing AG as a positive danger to their research paths and funding. EM isn't going to bother. Bezos is still years away from his first orbital launch.

Seriously, assuming someone comes up with a plan right now that actually gets funded, launch is still at least a decade away.

AG research is absolutely essential in my view but the ship has sailed. The first variable-g facility will probably be established on the Moon, after humans have been there for years already.

[Paul451]

No, because what is the different between humans experiencing 1/3 G on Mars and humans experiencing 1/3 G on an artificial gravity research station?

Billions upon billions of dollars, plus years of time before they can come home, (assuming your transport system has the capacity to bring them home in the same numbers as went out,) if we find humans can't handle long-term life on Mars.

[Edit: That said, I'm not disagreeing with Punder. Not only do we see opposition from within NASA, but even from those who want to bypass NASA, like Musk. We may only get the results we want when Musketeers start dying on Mars.]

[Coastal Ron]

No, because what is the different between humans experiencing 1/3 G on Mars and humans experiencing 1/3 G on an artificial gravity research station?

Billions upon billions of dollars...

The reality of the situation is that Elon Musk is going to Mars, and there will likely be a LOT of people that will volunteer to go - without knowing whether 1/3-G has deleterious effects on the human body. So they are going to be a HUGE ongoing experiment into many things, including 1/3-G effects.

...plus years of time before they can come home, (assuming your transport system has the capacity to bring them home in the same numbers as went out,) if we find humans can't handle long-term life on Mars.

People are willing to risk their lives for things like climbing the highest mountain on Earth, so does anyone think there will be a shortage of qualified people going to Mars on SpaceX transportation? People are AMAZING at rationalizing risk... 

Which is why we don't NEED artificial gravity stations to find out ahead of time if people can handle 1/3-G on Mars, colonists and visitors will tell us that.

But again, we will need artificial gravity to expand humanity out into space, and I do agree that we should start building such structures and spaceships as soon as possible so that we can iterate the designs as quickly as possible.

[Asteroza]

@Asteroza I was a little confused to by your description especially the reference to despun. Attached is my full description.

despun == non-rotating core for you

The basic dilemma is ease of access. Do you want a

1. truss framework mounted on the despun core, with attendant pressurized tunnels to manufacturing modules for shirtsleeve access? This effectively requires hard docking the manufacturing modules (at least when humans want access), plus vibration isolation measures up to whatever are practical limits.

2. Keep the modules on the truss backbone, but no tunnels, and use an OTV-esqe vehicle for service access? Same vibration isolation issues remain though.

3. Offboard freeflyer serviced by an OTV-esqe vehicle? Need effectively a full service module with power/cooling to provide house services to the manufacturing modules, but potentially could guarantee a much lower vibration environment and potentially better zero-g environment (any movement of humans to/from the ring to the core will not be smooth, janking around the core and anything attached to it)

[mikelepage]

despun == non-rotating core for you

The basic dilemma is ease of access. Do you want a

1. truss framework mounted on the despun core, with attendant pressurized tunnels to manufacturing modules for shirtsleeve access? This effectively requires hard docking the manufacturing modules (at least when humans want access), plus vibration isolation measures up to whatever are practical limits.

2. Keep the modules on the truss backbone, but no tunnels, and use an OTV-esqe vehicle for service access? Same vibration isolation issues remain though.

3. Offboard freeflyer serviced by an OTV-esqe vehicle? Need effectively a full service module with power/cooling to provide house services to the manufacturing modules, but potentially could guarantee a much lower vibration environment and potentially better zero-g environment (any movement of humans to/from the ring to the core will not be smooth, janking around the core and anything attached to it)

Probably option 3 is the only thing that will serve if you really need 0xG and no vibration.  Essentially telerobotic operation (during manufacturing runs) which can be easily serviced when necessary.

Otherwise you can probably have spun core module(s), containing a despun framework inside the pressure vessel that holds your equipment.

[spacenut]

Mars gravity may not affect humans as much while wearing spacesuits.  If a man weighing 150 lbs on earth, weights 50 lbs on Mars, but wears a 100 lb spacesuit, he still has to move around.  However, conditions may be different inside their habitats over the long term.

[Coastal Ron]

Mars gravity may not affect humans as much while wearing spacesuits.  If a man weighing 150 lbs on earth, weights 50 lbs on Mars, but wears a 100 lb spacesuit, he still has to move around.  However, conditions may be different inside their habitats over the long term.

That's one of the reasons why I don't think we need to wait for research on 1/3-G artificial gravity stations before going to Mars since the conditions on space stations (with limited room) are going to be significantly different than what would be experienced setting up colonies on the surface, and under the surface, of Mars.

[bad_astra]

No, because what is the different between humans experiencing 1/3 G on Mars and humans experiencing 1/3 G on an artificial gravity research station?

Billions upon billions of dollars, plus years of time before they can come home, (assuming your transport system has the capacity to bring them home in the same numbers as went out,) if we find humans can't handle long-term life on Mars.

[Edit: That said, I'm not disagreeing with Punder. Not only do we see opposition from within NASA, but even from those who want to bypass NASA, like Musk. We may only get the results we want when Musketeers start dying on Mars.]

They're going to die somewhere. Human mortality rate will remain, I am reasonably comfortable to say, 100% in the foreseeable future. The only way to reasonably handle a Mars colony in the era of chemical rockets is a one way trip, true, but that price and time disadvantage goes away with a lunar surface outpost, leaving no immediate needs for a rotating station any time soon. It will be needed at some point, sure.

It's building Bay Bridge when there's no San Francisco or Oakland yet.

[sghill]

The only use I can see for partial-g rotation is as a test of low-g human health.
However the moon is much closer

You think the moon is closer than LEO?

The cost of building a small test facility in LEO is much less than building a moon base. Let alone a Mars colony.

So shouldn't we learn if, for example, humans can actually handle long term Mars-g before we send humans?

When I hear about a test base with sub-orbital BFR operations going into Antarctica, let alone LEO, I'll believe they are getting real about Mars.

[Lampyridae]

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.

I think the scientific goal of using artificial gravity as a countermeasure, or using it to eliminate the effects of "being in space" for biological smaples (radiation etc) would dictate a different approach than artificial g for tourism. That kind of thing might simply be an evolutionary thing as space hotel "products" are developed. Circular running trucks on Bigelow modules (would not generate a "feeling" of gravity, as per Skylab astros) through to bigger internal setups like the standard 2001 internal carousel. I honestly feel that will be the actual roadmap, space agencies will just get cold feet over it and rather design a better space treadmill even with all the centrifuged rodent data they're going to get.

And as much as people say "Elon Musk is going to Mars," that in no way is a given. In addition to simply going off his rocker or shuffling off the mortal coil, Musk may simply fail to raise enough money to do it / not enough rich people might not actually like living underground on Mars eating powdered mealworms waiting for the next ships to bring new people to talk to and caviar. But somebody will do something in space - the capability is emerging for new commercial spaceflight opportunities.

[Roy_H]

@Asteroza I was a little confused to by your description especially the reference to despun. Attached is my full description.

despun == non-rotating core for you

The basic dilemma is ease of access. Do you want a

1. truss framework mounted on the despun core, with attendant pressurized tunnels to manufacturing modules for shirtsleeve access? This effectively requires hard docking the manufacturing modules (at least when humans want access), plus vibration isolation measures up to whatever are practical limits.

2. Keep the modules on the truss backbone, but no tunnels, and use an OTV-esqe vehicle for service access? Same vibration isolation issues remain though.

3. Offboard freeflyer serviced by an OTV-esqe vehicle? Need effectively a full service module with power/cooling to provide house services to the manufacturing modules, but potentially could guarantee a much lower vibration environment and potentially better zero-g environment (any movement of humans to/from the ring to the core will not be smooth, janking around the core and anything attached to it)

If you read my full description you'd know I picked option 3.
Description attached.

[Asteroza]

@Asteroza I was a little confused to by your description especially the reference to despun. Attached is my full description.

despun == non-rotating core for you

The basic dilemma is ease of access. Do you want a

1. truss framework mounted on the despun core, with attendant pressurized tunnels to manufacturing modules for shirtsleeve access? This effectively requires hard docking the manufacturing modules (at least when humans want access), plus vibration isolation measures up to whatever are practical limits.

2. Keep the modules on the truss backbone, but no tunnels, and use an OTV-esqe vehicle for service access? Same vibration isolation issues remain though.

3. Offboard freeflyer serviced by an OTV-esqe vehicle? Need effectively a full service module with power/cooling to provide house services to the manufacturing modules, but potentially could guarantee a much lower vibration environment and potentially better zero-g environment (any movement of humans to/from the ring to the core will not be smooth, janking around the core and anything attached to it)

If you read my full description you'd know I picked option 3.
Description attached.

Chanting "Dragon Lab!" while invoking the name of our lord and savior Musk does not a freeflyer make. Though it is a reasonable start, not withstanding fluids servicing issues. A "build it and they will come approach" where the freeflyer comes to the station is not entirely unreasonable either, rather than sending an OTV out for tending.

I'd point out that your choice of independent elevator cab module does directly lead to an OTV based on it, simply due to the high docking rate capable ports and reasonable life support systems (for when there is a docking problem with the elevator and riders get trapped, though the default for that is simply loading up with one time CO2 scrubber canisters and rescue balls while depressurizing the whole elevator module for rescue).

Many would argue for a despun backbone truss with tunnels and de-berthed but restrained modules (with reasonable motion/vibration isolation) for man tending is substantially easier and is the 80% solution.