Commercial Space Station Design

[sevenperforce]

There have been numerous threads about people in space, and reasons for people to be in space, and how it could possibly be economical to put people in space. There hasn't ever been much of a consensus.

However, we now (with the launch, mission, and splashdown of Dragon 2) have a way to put people in space, commercially, at a price that is at least reasonably low in comparison to every other possible launch provider in history.

Of course there isn't much of a destination at this point, other than the ISS.

So let us suppose, just for the sake of this thread, that someone constructs a business model for flights to a LEO commercial space station, and they execute. What would that station look like? I can think of a lot of different variables. Should you choose a low or a high inclination? With a polar orbit, can reach it from any point on the globe without a plane change, and the views are tremendous, but it's more challenging than a low-inclination orbit. It also limits return in a way that a lower-inclination orbit does not. There are many more questions:

• Eccentric or circular?
• Orbital period?
• Artificial gravity -- partial, none, or complete?
• Cartesian assembly or circular?
• Power management?
• Heat management?

I'm sure I'm missing many more...but if any group would be able to propose a lot of good ideas for a commercial space station (assuming, always, that the budget is large but not unlimited) it would be this group. What do you guys think? 

[Ultimate Steve]

10 minutes ago, sevenperforce said:

 

• Eccentric or circular?
• Orbital period?
• Artificial gravity -- partial, none, or complete?
• Cartesian assembly or circular?
• Power management?
• Heat management?

Sorry, I accidentally wrote an essay!

 

Eccentric would be great as you get to see variations in how far away Earth is, but it brings a few issues up. Too eccentric, and Dragon 2 won't be able to reach it. Too eccentric, and you're in the Van Allen belts, and that's no good. An eccentric orbit will also lead to different heating cycles, especially over the course of a year, you'll spend a different percentage of your orbit in sunlight/darkness as your periapsis could be facing the sun, but 6 months later your apoapsis is facing the sun... It shouldn't be a huge problem, but it should be considered. With those things considered, you can only make it a little elliptical, and at that point, the views aren't that much better, so I'd probably go with circular.

I'd stick with low Earth orbit, but maybe a bit higher than the ISS, giving an orbital period of 1.5-2 hours.

If the Van Allen belts weren't a thing, and Dragon 2 was more capable, I'd suggest a higher, very elliptical orbit, but unfortunately we have constraints.

I'm assuming this would be a tourism station, with maybe some science thrown in, but I might be wrong. If it's a tourism station, then I can't imagine people staying for much more than a few months. I watched a Mir documentary today, and it said that the cosmonauts mood got significantly worse after 3 months. Granted, this station will be much more modern than Mir. As far as scientific research goes, sticking with the 6 month system currently used by the ISS should work out fine. As a result of that, I'd give artificial gravity a no, especially since it hasn't really been tested. Plus, zero-g is a big part of the space tourist experience. Unless this is for a research station. Then, a partial gravity station would be alright. I'd love to see some Martian gravity experiments get done.

Not sure what Cartesian/circular is asking.

Power and heat are a few other things to consider. The simple answers are probably solar panels and radiators, but the specifics of that are pretty complicated.

A list of other things to consider:

• Communications
• Life support. (Oxygen, backup oxygen, food and water storage, water reclamation, etc.)
• Which docking ports to bring? It would be unwise to rely on just Dragon 2.
• Number of docking ports. I'd suggest at least 3.
• Viewpoints. Ideally something 2-3x as good as the Cupola module.
• Airlocks.
• How many modules?
• Space management. Where's the kitchen? Spacing of bathrooms? How big are the bedrooms? Etc.
• Current standardized systems. I know the ISS uses standardized racks for experiments and such.
• I'd probably design the whole thing in metric unless there are widely accepted standardized systems or Dragon 2 systems that use American.
• S T O R A G E. The lack of storage space was a HUGE problem on Mir, and is still a problem on the ISS, although to a lesser extent.
• Computer systems. Hardware? Operating system?
• Accessibility of components for repair.
• Fire suppression systems.
• Environmental controls, like temperature, humidity, etc. I read somewhere once that the ISS has cold and warm spots based on distance to temperature control systems.
• Airflow. I might be wrong, but IIRC the ISS has a lot of little fans to keep air circulating, because in zero-g CO2 could pool up around people's faces and that's definitely not ideal.
• Control. Reaction wheels or RCS thrusters? Both?
• Gravity gradient stabilization to save on fuel? I don't think it would work with such a small spacecraft, though.
• Will it have a robotic arm to aid in assembly if there are multiple modules?
• Microbe control. A big problem on Mir.
• Odor control. Also a big problem on Mir.
• Foreign gas filtering/control. If something unexpectedly outgasses and the system is not equipped to deal with that gas, it's going to stay in the station until it naturally leaks out, which will take quite a while.
• Hatch design, especially on multi modular designs.
• How many people should the station support at once?
• How long should the station keep them supported for?
•  Will it be continuously inhabited, or just when a spacecraft is visiting?
• What material should the main body of the station be made out of?
• Using inflatable modules would give more space and would be cool, but would probably mean buying from Bigelow.
• Exercise equipment.
• Propulsion for orbit boosting. Integrated, or only via visiting spacecraft?
• How are you getting the modules to the station? Designing a space tug? Integrated propulsion and control on every module?
• Inclination - I'd do about the same as the ISS so you can reach it from the same launch sites as the ISS. Russia, Florida, etc. Polar would mean most likely Vandenberg, which has never had a crewed launch and isn't set up for it.
• Wet workshop?!?!?!? Falcon 9 second stages are fairly large, but it's never been done before and brings its own host of problems, but that is a lot of extra volume.

Two more big ones.

Launch vehicle consideration. The biggest thing here is whether or not Starship becomes a thing.

	You design around Starship	You design around something else
Starship becomes a thing	Yay!	Your space station is small and expensive compared to just launching a group of people on a Starship.
Starship doesn't become a thing	You have oversized modules that can't be launched by anything and you can't recoup development costs.	Yay!

We can debate all day about whether Starship will work or not, but both are possibilities. I think it would be much more interesting to design around current rockets, however, especially as you are talking about Dragon 2, and there would probably be fewer unknowns. If we ignore Starship, our main options are:

• Falcon 9 - Low cost, smallish fairing.
• Proton - Larger fairing (I think), bigger payload, but they want to phase it out, it's a bit less reliable, etc.
• Atlas V - More expensive than F9, but about the same in capability once you factor in the capability lost for Falcon's reusability.
• Delta IV/Delta IV Heavy - Being phased out, really expensive, but can get a lot of stuff to orbit with a pretty big fairing, so probably no.
• H-II or H-III - Japanese launch vehicle. Capability similar to Falcon 9. H-II is more expensive, but H-III when it debuts, aims to be cheaper at about 50 million.
• Ariane 5/6 - More expensive, but similar capability to everything else.
• Soyuz - Price point probably similar to Falcon 9, less capability.

There are a few other serviceable options like Antares, GSLV, Zenit, Vulcan, etc. But those are our main options. Most signs point to the Falcon 9, but it would probably be unwise to be reliant on one company for everything, so a contingency option would probably be a good thing to have.

 

Another thing to think about is station end of life. Usually, stations are de-orbited, but I think it would be amazing if, at the end of this station's life, it was brought back to earth and placed in a museum. Granted, this relies upon a cheapish shuttle-like vehicle existing at the end of life date, like Starship or something. Things to consider when taking this approach are: The modules being able to be undocked, and redocked, being able to structurally handle re-entry when in a cargo bay, and probably a few other things.

 

Given these things, I think we can narrow this down to a few general designs:

1. Small-ish one module space station, extremely simple, launched on a Falcon 9 or similar. The size of a wider, larger school bus. Intermittently crewed by regularly launched Dragons. Might use Dragon's life support, even. Wait, that's probably a bad idea, scratch that. A place for tourists to stay, with large windows, to look down at Earth for a few days. It can be done in a reasonable timeframe on a reasonable budget, and might break even by the time Starship starts regularly operating. Pros: Low cost, simpler than other options, quickest to build option, most doable. But you have to pack everything into one module, including beds, windows, and all other systems. You wouldn't have to develop a space tug for docking, though.
2. Medium sized multimodular station for tourism and research. Basically a modern, smaller version of the ISS with a few modules. Multiple craft can dock, you can stay there for months. You get NASA as a customer as you have space to do research. You might even get development money from them if you are lucky. You have way higher development and launch costs, however, and you need to develop a space tug to get the modules to the station. You also risk not breaking even if Starship becomes a thing.
3. Go all-in on Starship. Design huge modules, build a huge thing, etc. Biggest risk, probably the biggest development cost (mitigated by the fact that you can have more design margin because of Starship's payload capacity), you have to wait for Starship to become a thing, if it does. Biggest payoff if it works. Potentially the lowest launch cost of all options. You also don't have to design a space tug if Starship is fitted with a robotic arm.

Personally, option one sounds the most interesting right now, as I think two would be too much to think about and there are a lot of what ifs on three.

 

Oof, that's a lot of stuff, so you probably won't have the time to comment on everything, but I'd like to hear what you have to say about some of it.

[qzgy]

 

19 minutes ago, Ultimate Steve said:

Not sure what Cartesian/circular is asking

My guess is would you make it a ring style station or a more iss like one, with things at right angles or 90 degrees and what not. 

[kerbiloid]

Spoiler

 

 

[Ultimate Steve]

13 minutes ago, qzgy said:

My guess is would you make it a ring style station or a more iss like one, with things at right angles or 90 degrees and what not. 

Ah, okay! I'd tend to go with ISS-like unless we have a large budget and a relatively inexpensive super heavy launch vehicle.

[sevenperforce]

24 minutes ago, qzgy said:

 

My guess is would you make it a ring style station or a more iss like one, with things at right angles or 90 degrees and what not. 

Yep, you were right.

You can conduct a ring station modularly.

[kerbiloid]

2 hours ago, sevenperforce said:

Eccentric or circular?

Any known crewed docking in a non-circular orbit?
(Except Apollo/LEM rearranging, of course.)

Definitely, circular.

2 hours ago, sevenperforce said:

Orbital period

Defined by the altitude.

2 hours ago, sevenperforce said:

Artificial gravity -- partial, none, or complete?

As artificial gravity requires radius, then "small several-person station without AG" vs "large tens-person station with AG".

2 hours ago, sevenperforce said:

Cartesian assembly or circular?

Small without AG, several persons - cartesian.
Large with partial AG, tens persons - cartesian with a rotating section made of a bunch of 4-m-wide parallel cylinders
Huge with full AG, for ~10k - rotating as a whole, hard bunch of 40-m-wide parallel cylinders.

2 hours ago, sevenperforce said:

Power management?

Nukes, to troll the greanpeace.

Small, several persons - exercycle+dynamo solar panels. 
Large with AG, tens persons - nuke
Huge with AG, for ~10k - Nuke

2 hours ago, sevenperforce said:

Heat management?

Any option in vacuum except the radiator panels?

2 hours ago, sevenperforce said:

Should you choose a low or a high inclination?

Small - high, to outsource photographing.
Large - low, because too many people to carry.
Huge - low or equatorial.

The economical model is the main question...

Edited March 11, 2019 by kerbiloid

[Green Baron]

Well, all imaginable designs for space stations and more are around somewhere, my question would be, what kind of "commerce" would the station be good for ? Who would travel to space for an exchange of ideas or to sell and buy things ?

I mean: would you set out on the ocean or on an airliner just for "commerce" or rather to travel from a to b ? Sure, you can do commerce in a vessel of any type, but the reason you boarded it was for travelling (or leisure), or not ?

But who (apart from the people who build giant yachts to do commerce on them) will go to space for commerce ?

And, may i say, it needs more than a crew capsule to build a station of any type. And, if i am not mistaken, such a contraption must be in a high orbit to avoid collisions with the fast growing cloud of things up there.

Edited March 11, 2019 by Green Baron

[kerbiloid]

2 minutes ago, Green Baron said:

what kind of "commerce" would the station be good for ?

Off-shore banking. Literally.

[Lisias]

1 hour ago, Green Baron said:

I mean: would you set out on the ocean or on an airliner just for "commerce" or rather to travel from a to b ? Sure, you can do commerce in a vessel of any type, but the reason you boarded it was for travelling (or leisure), or not ?

In the 70s and 80s, India had no footprint on IT. None. Zero. Squat.

But they had a lot of cheap human labor. So they started to sell low tech IT services for Europe, specially Data Typing. At that time, digital telecommunication was in their infancy, but it already was there using dial-ups and modens from 300 to 2400 and even 9600 (expensive as hell, by the way), and companies were starting to get digital somehow - with tons and tons of documents in need to be typed in order to be processed.

India offered the best service at the time, guaranteeing up to 100% error free: they put two or more typists working on the same data (as much as the client wanted to pay for accuracy), compared the results, and typed again anything that mismatched. Europeans mailed the tons os papers to be typed, India transmitted back the data by modem.

And then there was no more Data Typing Bureau in Europe, and there were no more available clients for the emerging IT industry on India. So they tried USA - but USA was too far away, air mailing tons of paper would be expensive as hell and shipping by water unfeasible -not to mention transmitting back the data on noisy underseas copper cables. And, of course, moving to USA and paying all the local taxes and labor fees would make the deal unattractive.

So they just hired a freaking transatlantic, anchored it overshoes at the international waters and put a lot of Indians typing night and day, with boats bringing the jobs and delivering the tapes with the data to be mailed or transmitted on the continent.

And that was the demise of the Americans Typing Bureaus too.

I don't know exactly what will be the type of service, but I bet that something like that will be the first economical race to the Space; tax and labour fess evasion.  

[Green Baron]

Earthly analogies don't work in a deadly environment where one has to bring in every single molecule necessary for upkeep. Earth has infrastructure, atmosphere, gravity, shielding, water and food. Space not. Models and depictions of space stations are available for a cent a dozen, none is realistic (yet ? ever ?).

There are more than enough competing opportunities for all types of "commerce" here on earth, where there is air and food and no immanent danger of technical failure. The guys from that "commercial" model (IT, tax exemption, whatever) usually are not the ones who love to live risky ;-)

The longer i think about it (30 seconds or so :-)), the more i think that a station for commerce makes no sense.

Edit: searching "space station design" just results too much information :-)

Edited March 11, 2019 by Green Baron

[kerbiloid]

Spoiler

53 minutes ago, Lisias said:

In the 70s and 80s, India had no footprint on IT. None. Zero. Squat.

https://2001.fandom.com/wiki/Dr._Chandra

Spoiler

53 minutes ago, Lisias said:

guaranteeing up to 100% error free

 

Edited March 11, 2019 by kerbiloid

[YNM]

10 hours ago, sevenperforce said:

Eccentric or circular?

Sadly, circular. But :

10 hours ago, sevenperforce said:

Orbital period?

I'll go with orbital height: Fairly high, so while you don't see the roundness of the Earth change at the station, it'll continually change during rendezvous. Downside is, the occupants spend more time at the capsule, so we'll need something comfy... but comfy is cost.

10 hours ago, sevenperforce said:

Artificial gravity -- partial, none, or complete?

Probably none, or we'd have rotating torus such that you can feel gravity when you want to but also feel none of it when you want so. As a result...

10 hours ago, sevenperforce said:

Cartesian assembly or circular?

... already answered above.

10 hours ago, sevenperforce said:

• Power, Heat ?

Standard fins and PV panels. Probably on a dedicated truss area.

 

8 hours ago, Ultimate Steve said:

Which docking ports to bring? It would be unwise to rely on just Dragon 2.

IDSS should be supported better in the future. Dragon 2 is the first implementation.

Would have both docking ports and berthing - the berthing system would have to be drawn-up such that you can transfer fuels and liquids across it.

8 hours ago, Ultimate Steve said:

Airlocks

... Through berthing/docking ports ?

8 hours ago, Ultimate Steve said:

Airflow

Must. Dusts don't fall off the air in space, so the air has to be moved around continuously (and filtered and cleaned).

8 hours ago, Ultimate Steve said:

robotic arm

Must, given berthing. But only in the ports area.

8 hours ago, Ultimate Steve said:

• How long should the station keep them supported for?
•  Will it be continuously inhabited, or just when a spacecraft is visiting?

Depends on the size. If we're talking something meant for >10 people, continuous. If less, then only in preparation for tourists.

Edited March 11, 2019 by YNM

[magnemoe]

3 hours ago, Green Baron said:

Well, all imaginable designs for space stations and more are around somewhere, my question would be, what kind of "commerce" would the station be good for ? Who would travel to space for an exchange of ideas or to sell and buy things ?

I mean: would you set out on the ocean or on an airliner just for "commerce" or rather to travel from a to b ? Sure, you can do commerce in a vessel of any type, but the reason you boarded it was for travelling (or leisure), or not ?

But who (apart from the people who build giant yachts to do commerce on them) will go to space for commerce ?

And, may i say, it needs more than a crew capsule to build a station of any type. And, if i am not mistaken, such a contraption must be in a high orbit to avoid collisions with the fast growing cloud of things up there.

Main purpose it to rent out for research, this can be everything from adding parts to the station to simply putting an sample on the outside for long term space exposure. 
NASA and other would purchase this as an service, the station owners would be responsible to run and maintain the station also run it as an hotel for the researchers. 
Pretty sure NASA would enter an long term rent here who would be the give the project an stable guarantee income. 

One problem with ISS is that the crew spend most of their time maintaining the station leaving little time to research. 

Down the line tourism might be relevant 
Also stuff like assemble structures like antennas for used on satellites 

[Lisias]

2 hours ago, Green Baron said:

Earthly analogies don't work in a deadly environment where one has to bring in every single molecule necessary for upkeep. Earth has infrastructure, atmosphere, gravity, shielding, water and food. Space not. 

The transatlantics hired by India to do data typing overshores to USA hasn't neither - except by breathable air. Food, water, medcare, everything has to come from the continent.

Since prices on USA were way higher than on India, given the scale of the enterprise, such provisions probably were sent from India using cheap shippings by ship (couldn't help myself on this  ).

Once kicking provisions to space is cheap enough by kilogram sent (what not mean that the shipment itself would be cheap - compare the prices of shipping a container with the cost of the ship and the fuel for the trip), my guess is that some kind of stunt like I described would be probably the entry point for a lot of poor countries on space.

 

1 hour ago, kerbiloid said:

https://2001.fandom.com/wiki/Dr._Chandra

In 1968, the first IT plant on India (practically Burroughs, using Tata as local dealer) was just one year old. From 1973 to early 80s (less than 10 years), the presence of the Indian IT on the World were insignificant in absolute numbers [but they were there already!!!], but on the 80's the growth was astonishing. Absolutely astonishing, in 1983 or 84 half the IT magazines of that time were talking about India (it was this way that I learnt about the transatlantic stunt, and when in the 90's they published about the IT Services Bureau demise in Europe, I already knew the reason).

I bet my mouse Arthur C Clarke knew about Mumbai, and wonder if he did it to prank IBM - that was acting as tech consultant for Kubrick on the movie. Clarke wrote the script/book at the same time Kubrick shoot the picture.

Source: https://en.wikipedia.org/wiki/Information_technology_in_India

Edited March 11, 2019 by Lisias
Typo and an additional remark to better clarify the idea (in italics)

[CastleKSide]

 

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

"In October 2010, Bigelow announced that it has agreements with six sovereign nations to utilize the on-orbit facilities of the commercial space station: United Kingdom, Netherlands, Australia, Singapore, Japan and Sweden."

A bit off topic, but addressing the concerns that a commercial space station doesn't have a viable business model, Bigalow thinks they have one and I doubt the nations are getting free access. When it comes to evaluating a proposed business I trust the capitalist.

 

[Green Baron]

hmm ... do they have one customer who pays 25m$ to rent a yet non existent module ? It has become quiet around them ... after all the announcements. I doubt that there is actual business for them.

Edited March 11, 2019 by Green Baron

[Lisias]

5 hours ago, Green Baron said:

hmm ... do they have one customer who pays 25m$ to rent a yet non existent module ? It has become quiet around them ... after all the announcements. I doubt that there is actual business for them.

Musk didn't have [HAD] a client willing to pay for his rockets when he started Space-X.

Neither Bezos with his Blue Origins - but this one had some funding by (indirectly) participating on government funded programs some time later.

Virgin Galactic already sold some tickets to space, by the way.

From all of these, who is commercially operative and recently docked on ISS?  Yep. That crazy loud mouth called Musk.  

Life is more interesting than our imagination sometimes.

Edited March 11, 2019 by Lisias
AAAAAARRGH!!!! :( (hate touchscreens and especulative auto-completes)

[StrandedonEarth]

I see two likely customers for a commercial station: Hotels (tourism) and film studios, for unmatched realism (the novelty factor alone will sell tickets for the first few movies). 

Logistics depot is another possibility down the line. 

One thought about power/heat: As many ways to reclaim heat back into power as reasonable (thermocouples and such)

[Green Baron]

2 hours ago, Lisias said:

Musk didn't have a client willing to pay for his rockets when he started Space-X.

He had NASA. And that's something different. There was need for a rocket, especially was there need for a capsule to transport humans to the ISS. He first tried to buy Russian hardware for the first steps, that didn't work because too expensive, then he invested some of his own multi billion money and offered his private stuff like plane and soon after the first tests were successful got a multi billion funding from NASA. His rockets do fly and i believe even earn money, if we take the funding for granted. I doubt they can ever pay that back.

But i don't see any reason or need for a commercial space station, a tourist every 2 years isn't enough. Ok, i am exaggerating, but not much :-)

Edited March 11, 2019 by Green Baron

[kerbiloid]

"Vintage-Garbage"
Garbage collectors. Cleaning the orbit. Gathering, repairing, and selling vintage devices.
Getting to your upper stage and delivering it to the recycler.

(Also can spy the customer's spouse with a telescope.)

[NSEP]

Having Starship wouldn't have a big advantage for a tourism station, it would have an immense advantage.

A wet workshop Starship can give you around 2000m^3 in a single launch. That is more than enough to house 100 tourist comfortably at a time for a week stay, perhaps even 200 people. Heck, even as a bonus if Super Heavy is capable of doing SSTO flights, and we would do a wet workshop mission on the empty booster (with not much payload) in orbit, that will give us around 4000m^3 of volume to mess around with, then also turn the Starship used to send cargo to the empty Super Heavy vehicle and turn that into a wet workshop as well. Double Bonus. 6000m^3, enough for 300-600 tourists.

(maybe just launching seperate more conventional modules will turn out to be more cost effective, however, but we will see i geuss)

All we have to do now is add power, air conditioning, radiators, and all that kind of stuff that will make you go ''oh its still going to be extremely expensive and complex'' and there you go boom.

An important thing about space hotels is cost. In order to make space tourism in orbit affordable for the common public, you need tens of thousands of tourists costumers coming to a cheap tin can space station every year. Its sort of like the ''Cost per KG'' thing, the best way to lower the cost is to make stuff bigger and dumber, although ''dumb'' might not go that well with manned spaceflight.

Edited March 11, 2019 by NSEP

[Lisias]

2 hours ago, Green Baron said:

He had NASA. And that's something different. There was need for a rocket, [cut by me]

The freaking autocomplete "typed" have, I meant HAD. (sigh). This changes your line of arguing somehow?

If not, yes. There was a need for a new and cheaper rocked, and that's the reason SpaceX managed to get there.

 

2 hours ago, Green Baron said:

But i don't see any reason or need for a commercial space station, a tourist every 2 years isn't enough. Ok, i am exaggerating, but not much :-)

Being probably the reason Musk is betting on Mars and Moon.  

So, yeah. People willing to build that space station will need to pull it out a need from their hat. Tax evasion usually is a very lucrative reason. So I stick with my argument - one of the main uses of such space station will be tax and labour fee evasion.  

[sevenperforce]

Starship will definitely be a gamechanger, if it gets up and running. For the moment, though, we're limited to what can be flown on existing hardware.

With respect to inclination...higher is better for universal access. You can access a near-polar orbit from the Cape; you just need to do a bit of a dogleg, which Falcon 9 can certainly do. If you do an 80-85° inclination, then you can burn due south (or even south-southeast) because there's enough of a circumferential component to the orbital velocity that you don't need to cancel Earth's rotation like you do with a true polar orbit.

Nonzero orbital eccentricity could be very interesting if the argument of periapsis was equal to the inclination. Then, your farthest distance from Earth takes you (nearly) over the south pole and you zip at high speed over the north pole. Heat management remains the same year-round and the "night" portion of the transit is brief. For certain portions of the year, there is no night on the space station at all. You get the visual impact of eccentricity but there isn't much trouble with phasing at launch because each launch site has roughly the exact same parameters for each launch window.

One of the earlier comments involved air circulation; you need fans to move air around or it will just sort of pool up. Another discussed artificial gravity, and another reaction control. There could be a way to handle all simultaneously. If the station is constructed as a torus with an open hallway running all the way around the circumference, then fans could be designed to push air around the hallway to induce a very, very slight breeze. The moving air would be enough to produce a small rotation of the station...not enough to cancel the sense of weightlessness, but enough that objects naturally settle outward rather than floating endlessly. You could adjust orientation by reversing the fans, etc.

With respect to heat and power management, I guess the question is whether you'd be looking at gimballed radiators a la ISS, or panel radiators like on the Dragon 2 trunk. It would also be really cool (no pun intended) if the station dispensed with traditional solar arrays altogether and used circulating coolant from sunside to shadeside as its primary power source. 

[HvP]

5 hours ago, StrandedonEarth said:

... film studios, for unmatched realism (the novelty factor alone will sell tickets for the first few movies).

I'd bet on that happening at some point. With the most expensive blockbuster films running a quarter-billion dollars the cost of a SpaceX flight seems like a match made in heaven... er, the heavens.

The biggest hurdles to that would be the weight cost of equipment and the space required to block out filming. You can rent a whole "vomit comet" for less than $200,000 with plenty of room to work. Of course, you're stuck with short takes of thirty-seconds or less.

Still, with the cost of launches coming down and the cost of movies going up, it's only a matter of time.

Edited March 11, 2019 by HvP