Author Topic: Realistic, near-term, rotating Space Station  (Read 944960 times)

Offline Aussie_Space_Nut

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Re: Realistic, near-term, rotating Space Station
« Reply #1240 on: 10/08/2018 07:25 am »
The centre hub has a module such that [...] the inner lab remains stationary.

After re-reading, I realise that I (and I think others) misunderstood your comment as relating to the discussion on docking. I now realise it has nothing to do with that topic. You're just talking about creating a micro-g lab by counter-rotating a room inside of the hub.

That's it! :-)

Offline jee_c2

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Re: Realistic, near-term, rotating Space Station
« Reply #1241 on: 10/19/2018 06:15 am »
Kleos Space, Airbus collaboration: MoU signed
http://www.spacedaily.com/reports/Kleos_Space_signs_MoU_with_Airbus_to_collaborate_on_In_Space_manufacturing_technology_999.html

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... Kleos Space and parent Magna Parva (UK) have developed an In-Space manufacturing system that will provide a method of producing huge carbon composite 3D structures in space. A prototype system has been successfully built and tested under 'near space' conditions at Kleos' development facility. ...

Offline indaco1

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Re: Realistic, near-term, rotating Space Station
« Reply #1242 on: 10/27/2018 09:39 am »
Artificial gravity is not just for the crew.

It could be used to keep deployed very light but huge structures eg. flexible solar panels, solar sails, tethered modules and even for fluid storage and transfer (eg. BFS will use milli-g artificial gravity feed). 

I've seen many concepts that use rotation to deploy structures in the literature.



Non-native English speaker and non-expert, be patient.

Offline whitelancer64

Re: Realistic, near-term, rotating Space Station
« Reply #1243 on: 10/31/2018 07:00 pm »
Would anyone mind if I briefly!! derail this thread?

I want to turn the question around:

Given the use of a high-strength steel - we have developed some alloys with tensile strengths well above 2000 MPa - what, approximately, is the largest rotating space station we could build?

I've read on an old forum that using Titanium we could, in theory, safely make a rotating space station with a radius of 14 km (88 km circumference). Side note: Rotating that for 1g is 0.25 rpm. (0.25 rpm = 360 r/ day or 15 r/ hour)
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Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1244 on: 10/31/2018 07:56 pm »
Would anyone mind if I briefly!! derail this thread?

I want to turn the question around:

Given the use of a high-strength steel - we have developed some alloys with tensile strengths well above 2000 MPa - what, approximately, is the largest rotating space station we could build?

I've read on an old forum that using Titanium we could, in theory, safely make a rotating space station with a radius of 14 km (88 km circumference). Side note: Rotating that for 1g is 0.25 rpm. (0.25 rpm = 360 r/ day or 15 r/ hour)

I think your question meets the topic of this thread, since we're talking "realistic, near-term".

I don't know if "largest" means anything once you reach a size where humans are comfortable in a rotating space station that provides one Earth gravity - who cares if it is 200m in diameter or 1,000m in diameter? Although a larger station may mean a larger community, or provides for more open space for growing crops, etc. All good things, but not sure if that is "realistic, near-term" yet.

Once size becomes an option then I don't think it's material strength that becomes the gating issue, but logistics - how to get that much mass to the construction site in space.

For instance, I have a conceptual design that relies on Ultra-high-molecular-weight polyethylene like Dyneema to keep mass down, and it could scale up to something really massive with a future design that would look like a cocoon just by wrapping more layers around the exterior. But we don't have the logistics to build something of that size today, which is why I'm working on something more mass efficient.
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 whitelancer64

Re: Realistic, near-term, rotating Space Station
« Reply #1245 on: 10/31/2018 08:42 pm »
Would anyone mind if I briefly!! derail this thread?

I want to turn the question around:

Given the use of a high-strength steel - we have developed some alloys with tensile strengths well above 2000 MPa - what, approximately, is the largest rotating space station we could build?

I've read on an old forum that using Titanium we could, in theory, safely make a rotating space station with a radius of 14 km (88 km circumference). Side note: Rotating that for 1g is 0.25 rpm. (0.25 rpm = 360 r/ day or 15 r/ hour)

I think your question meets the topic of this thread, since we're talking "realistic, near-term".

I don't know if "largest" means anything once you reach a size where humans are comfortable in a rotating space station that provides one Earth gravity - who cares if it is 200m in diameter or 1,000m in diameter? Although a larger station may mean a larger community, or provides for more open space for growing crops, etc. All good things, but not sure if that is "realistic, near-term" yet.

Once size becomes an option then I don't think it's material strength that becomes the gating issue, but logistics - how to get that much mass to the construction site in space.

For instance, I have a conceptual design that relies on Ultra-high-molecular-weight polyethylene like Dyneema to keep mass down, and it could scale up to something really massive with a future design that would look like a cocoon just by wrapping more layers around the exterior. But we don't have the logistics to build something of that size today, which is why I'm working on something more mass efficient.

Well, the old Cosmoquest post I read said that with carbon nanotubes, rotating space stations up to 1,000 km in radius would be possible, and mentioned that with run-of-the-mill steel, only a diameter of ~3.4 km is possible (but such steel is very cheap which is why the Sanford Torus design used that size).

I guess I am looking for a specific answer to what is, at least theoretically, possible with currently-available high-strength steel alloys, but I'm completely ignorant of the math that was used to derive these radii.

You are correct that past the "comfort level" it really doesn't matter, other than you get really impressive living areas the larger they are; the 88 km in circ. (possible with Titanium) if 1 km wide, would have a greater 1g area than some island nations and could be, very comfortably, home to several tens of thousands of people.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline TrevorMonty

Re: Realistic, near-term, rotating Space Station
« Reply #1246 on: 10/31/2018 10:42 pm »
If we are building these size structures the steel will be coming from asteriods or moon. When comes to Titanium verus steel its trade between higher energy required to process titanium ore for lower transport mass.


Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1247 on: 10/31/2018 11:38 pm »
Well, the old Cosmoquest post I read said that with carbon nanotubes, rotating space stations up to 1,000 km in radius would be possible...

Unfortunately not something that would be considered "realistic" at this point.

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...and mentioned that with run-of-the-mill steel, only a diameter of ~3.4 km is possible (but such steel is very cheap which is why the Sanford Torus design used that size).

I don't see the cost of material as being the biggest cost driver for a full sized rotating space station, so I don't think starting your assumptions with steel is a good idea. Plus you have to consider the type of construction that will be used, and I don't think welding or riveting steel plates and beams will make sense.

That said, ~3.4 km for a diameter is far bigger than anything that could be built "near-term", so I guess steel could be used.

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I guess I am looking for a specific answer to what is, at least theoretically, possible with currently-available high-strength steel alloys, but I'm completely ignorant of the math that was used to derive these radii.

I use SpinCalc for helping to define rotation and gravity, then I estimate mass, then I calculate the strength needed to hold all that mass together - then I double that number.

But I'm not an engineer, and my design has lots of room for additional strengthening without affecting usable space.

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You are correct that past the "comfort level" it really doesn't matter, other than you get really impressive living areas the larger they are; the 88 km in circ. (possible with Titanium) if 1 km wide, would have a greater 1g area than some island nations and could be, very comfortably, home to several tens of thousands of people.

When talking about a "Realistic, near-term, rotating Space Station", to me that means a very small community that will be proving out what is needed to move from a Generation One rotating space station, to a Generation Two version.

So let's focus on Generation One, which is likely between 200-500m in diameter, depending on a rotation of 2-3 RPM. Many would advocate it could be smaller than 200m, and rotate faster than 3 RPM - and they may be right (no debate, I'm just putting it out there). So that is a good starting 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?

Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #1248 on: 11/01/2018 03:53 am »
One notion I would like to get away from is this idea that rotating stations are ever “finished” (as in having two phases of life: construction and use).

I think the architecture has to be such that one of the main activities of people living onboard the station is building the station. When we finally have gigantic stations, I don’t think they’ll ever be “brand new”. Rather, I think they’ll be the result of years/decades of modular construction, with new layers at larger radii being added around the circumference of the previous layer, and even these will be intended to serve as a framework for the next phase of construction.

Offline TrevorMonty

Re: Realistic, near-term, rotating Space Station
« Reply #1249 on: 11/01/2018 05:15 am »
One notion I would like to get away from is this idea that rotating stations are ever “finished” (as in having two phases of life: construction and use).

I think the architecture has to be such that one of the main activities of people living onboard the station is building the station. When we finally have gigantic stations, I don’t think they’ll ever be “brand new”. Rather, I think they’ll be the result of years/decades of modular construction, with new layers at larger radii being added around the circumference of the previous layer, and even these will be intended to serve as a framework for the next phase of construction.
If always assumed construction would happen under 0g but there is nothing stopping construction of new outer rings while rotating. Materials would just need to  be lower from inner ring.

Start with small inner cylinder or ring operating at low g eg 1/10 then expand outward.

Offline Aussie_Space_Nut

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Re: Realistic, near-term, rotating Space Station
« Reply #1250 on: 11/01/2018 06:22 am »
What I found really hard to get my head around is the mass of shielding material. If you go for an O'Neil Cylinder station with a 2 metre thick moist soil growing medium/radiation shield in a 100 metre radius station then you do the calcs on how much mass! Yikes! It's a very very very massive thing! How would you adjust the position of such a massive thing?

So you have to go to LEO to reduce your shielding.

But then you have to boost regularly so the whole thing can't be too massive......

You tend to just go around and around and around in a circular debate with no ideal solution.
(If you want a safe extended stay for many years that is.)

It seems to me that unless someone cracks the "Star Trek Shields" thing we are going to be stuck doing short term stays in space due to radiation. Therefore no rotating station required at this time. :-(

Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #1251 on: 11/01/2018 07:47 am »
What I found really hard to get my head around is the mass of shielding material. If you go for an O'Neil Cylinder station with a 2 metre thick moist soil growing medium/radiation shield in a 100 metre radius station then you do the calcs on how much mass! Yikes! It's a very very very massive thing! How would you adjust the position of such a massive thing?

So you have to go to LEO to reduce your shielding.

But then you have to boost regularly so the whole thing can't be too massive......

You tend to just go around and around and around in a circular debate with no ideal solution.
(If you want a safe extended stay for many years that is.)

It seems to me that unless someone cracks the "Star Trek Shields" thing we are going to be stuck doing short term stays in space due to radiation. Therefore no rotating station required at this time. :-(

Don't discount Equatorial LEO (<5°) too quickly, I think there is a sweet spot in ELEO somewhere around 600km, where orbital lifetimes are about 20 years, and radiation levels from GCR are below 40mSv/year with no shielding. 

http://space.alglobus.net/papers/Easy.pdf

Better (for radiation purposes) to be around 600km, as radiation in ELEO ramps up quickly as you go up in altitude (up into the inner Van Allen Belt), but you could go to 800km, where orbits are 100 years plus, and still only require a fraction of the shielding you need in interplanetary space.

Offline TrevorMonty

Re: Realistic, near-term, rotating Space Station
« Reply #1252 on: 11/01/2018 09:23 am »
The shielding can also be in an outer shell that doesn't rotate. Need a lot of shielding but support structure required to hold it in place is very light as its 0g.
No practical for LEO but ideal for Langrange point or even better asteriod belt where lots of shielding construction material is very low DV away.

If we are building an Oneil cylinder anywhere near moon then mass drivers to deliver material from moon is a given. In which case a few million tons of regolith delivered by steel canistors shouldn't be an issue. The steel would be used for construction of cylinder.

Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1253 on: 11/01/2018 09:06 pm »
One notion I would like to get away from is this idea that rotating stations are ever “finished” (as in having two phases of life: construction and use).

I think the architecture has to be such that one of the main activities of people living onboard the station is building the station. When we finally have gigantic stations, I don’t think they’ll ever be “brand new”. Rather, I think they’ll be the result of years/decades of modular construction, with new layers at larger radii being added around the circumference of the previous layer, and even these will be intended to serve as a framework for the next phase of construction.

I think that's asking too much of the designers, and too much of the early users. And we certainly don't use that method of construction here on Earth as a standard. For instance, we don't build a single level dwelling, turn it into an apartment complex, and then scale it up to a residential skyscraper.

Just as here on Earth we start with Generation One, then move onto Generation Two, then Three and so one, so it will be in space for just about everything (i.e. space stations, space ships, refueling depots, mining colonies, etc.).

I think a Generation One rotating space station will be the "minimum viable dwelling" (ala an MVP) that we can build to prove out many critical assumptions that go with rotating space stations. Such as:

- Rotation speeds
- Minimum gravity levels below 1G
- Distance from Earth for logistics reasons
- Safe radiation levels
- Features
- Self-sufficiency levels (i.e. consumables like food, water, etc.)

We shouldn't try to solve all of those challenges with our first design, and the first design should not be something that takes 100 years to finish. It's OK to finish building something and then move onto the next one. I'm remodeling my house right now, and it's no fun being in a dwelling that is not finished...  ;)
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 DistantTemple

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Re: Realistic, near-term, rotating Space Station
« Reply #1254 on: 11/01/2018 10:00 pm »
It seems in the same vein as SX's iterate... design and test/fly and see how it works then improve, compared to traditional space spending many years trying to design it exactly right, for all outcomes, and taking forever over it. After all the first generation rotating station will have a purpose as the next is built and comes online!
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Offline mikelepage

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Re: Realistic, near-term, rotating Space Station
« Reply #1255 on: 11/02/2018 03:47 am »
One notion I would like to get away from is this idea that rotating stations are ever “finished” (as in having two phases of life: construction and use).

I think the architecture has to be such that one of the main activities of people living onboard the station is building the station. When we finally have gigantic stations, I don’t think they’ll ever be “brand new”. Rather, I think they’ll be the result of years/decades of modular construction, with new layers at larger radii being added around the circumference of the previous layer, and even these will be intended to serve as a framework for the next phase of construction.

I think that's asking too much of the designers, and too much of the early users. And we certainly don't use that method of construction here on Earth as a standard. For instance, we don't build a single level dwelling, turn it into an apartment complex, and then scale it up to a residential skyscraper.
I could have been clearer. I didn’t at all mean that every single rotating station need be expansible (in fact I think most of them will be “spaceships” designed for significant dV). We’re going to build a number of those first to work out all the factors you mentioned. 

My point was just that I think the ones that become gigantic will have expansibility and self building as a core characteristic. These constructions are less analogous to single buildings than a whole city. You don’t see skyscrapers being built in the middle of the wilderness (because it needs a construction base), but the evolution of a city is that you first see single story dwellings, then multistories, then skyscrapers, often built on top of each other as time progresses.

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I'm remodeling my house right now, and it's no fun being in a dwelling that is not finished...  ;)

Well yeah 😜 you have lowered functionality as a result of the process. What I’m thinking is more like if you are living in a totally functional house, but the next block over was having a new residential development built. You might be able to hear the construction sometimes, but it’s not going to bother you much.
« Last Edit: 11/02/2018 05:32 am by mikelepage »

Offline Coastal Ron

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Re: Realistic, near-term, rotating Space Station
« Reply #1256 on: 11/02/2018 04:27 am »
My point was just that I think the ones that become gigantic will have expansibility and self building as a core characteristic. These constructions are less analogous to single buildings than a whole city. You don’t see skyscrapers being built in the middle of the wilderness (because it needs a construction base), but the evolution of a city is that you first see single story dwellings, then multistories, then skyscrapers, often built on top of each other as time progresses.

Talking about "gigantic" space stations is OT though, since they are not "realistic" nor "near-term". It is a fun topic though, but it should really be discussed elsewhere...

Quote
Quote
I'm remodeling my house right now, and it's no fun being in a dwelling that is not finished...  ;)

Well yeah 😜 you have lowered functionality as a result of the process. What I’m thinking is more like if you are living in a totally functional house, but the next block over was having a new residential development built. You might be able to hear the construction sometimes, but it’s not going to bother you much.

I'm thinking that a Generation One, realistic, near-term rotation space station will be more like a cruise ship than a suburban neighborhood, where the design will be planned out for all the parts of the station.

I also agree with you that the station itself won't be completely operational by itself. I think that wherever the station is, that it will have a fleet of support vessels to service it.
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 #1257 on: 11/02/2018 07:26 am »
Talking about "gigantic" space stations is OT though, since they are not "realistic" nor "near-term". It is a fun topic though, but it should really be discussed elsewhere...

<snip>

I'm thinking that a Generation One, realistic, near-term rotation space station will be more like a cruise ship than a suburban neighborhood, where the design will be planned out for all the parts of the station.


This discussion made me realise some implicit assumptions I've been making when I write about this (thanks), and I can't really explain them without writing about what I've been working on.

Those of you who have followed my previous posts will have seen me mention our (Exodus Space Systems') work on the Deployable Toroid Array (DeTA).  I don't like to do it too much because I really don't want to spam the thread, and there are some IP issues as well.  But I've created a new short video to show our progress to our investors, so I might as well share it here.  Note that DeTA is a "space origami" concept, which also has fractal-like properties:



Basically, when I talk about DeTA architecture, I'm talking about this folding geometry which is inherently scalable to whatever dimensions you want.  We're currently working on a prototype which is the size of a wastepaper basket, and aiming to fly one the size of a washing machine, but you could equally well scale this geometry up to human dimensions.  The most recent version shown in the video has an inner ring and an outer ring, but that outer ring (once locked in place) could easily enough become the inner ring for a larger radius DeTA with twice as many spoke/rim segments. 

Conceptually you can keep doubling spoke/rim segments for ever larger radii - that's why I call it fractal-like, and that's why I think those eventual gigantic stations we spoke about upthread could still have a common architecture with much smaller, realistic, near-term stations.

Of course, you could also do that kind of doubling to increase size without the complication of the articulated motion, but there are a number of reasons why you might want to be able to articulate into a stowed position whilst in space, not just because it fits into the payload bay of your launch vehicle better:  Whenever you have to apply significant delta V to the craft (for interplanetary injection burns, or station keeping), your craft can be much more lightweight if it has a stowed configuration where you can lock everything down before you perform the burn.  Also, there's some orientation control advantages you gain from having a "flywheel" with a variable moment of inertia. 

Perhaps most importantly, notice how the space at the very centre of the stowed config would have the extra protection you want for a radiation shelter.  Which is something you need sporadically/infrequently when you find out (with perhaps an hours notice) that there's a solar CME heading in your direction.  It's inevitable that some manned craft on an interplanetary trajectory will eventually get caught out in the open when a CME explodes past them, but it's inefficient to have large amounts of water/polyethylene/other shielding material ready at all times to shield the craft's crew.  Better that the craft itself can fold into a "turtle" protected configuration, and it won't matter if the crew go without spin G for a few hours/days while they ride out the storm.   


Offline Lar

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Re: Realistic, near-term, rotating Space Station
« Reply #1258 on: 11/14/2018 04:56 am »
Rotating Habitats and Asteroids split out to new subtopic, please use it

https://forum.nasaspaceflight.com/index.php?topic=46759.0

thanks to Paul451 for the suggestion.

Remember, if YOU are the splinter starter, you can just splinter it yourself by starting a new topic using the post you want to quote and your words... this saves mod work.

If a splinter starts, and has replies, a mod can split it out. Use Report To Mod and give the starting post for the splinter and if you can. a suggested title. if there are posts that might be easy to miss, give their links too. Thanks!
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Offline sanman

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Re: Realistic, near-term, rotating Space Station
« Reply #1259 on: 01/07/2019 05:29 am »
So what if we just discuss something simple - like a pair of modules rotating around another module-hub?

They could be linked together by a scaffolding/ladder. There could be a flexible pressurized sleeve-tube envelope surrounding that ladder, acting as a traversible corridor to link the modules together. To get from one module to another, you just climb up/down the ladder.  So the ladder would look like a tubular stack of rings that are spaced apart like rungs, held together by longitudinal pipes.

So you've mentioned that weight-shifts in the system (due to movement of people, etc) can throw the rotation out of balance and cause it to precess/tumble. But you've also said that this could be compensated for by mass-transfer, such as fluid flow/pumping.
So the longitudinal pipes on the ladder thing could channel fluids from one side to the other.

Now what else do we need to address, to get our simplest-case system to work?
« Last Edit: 01/07/2019 06:16 am by sanman »

 

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