Quote from: Aussie_Space_Nut on 10/05/2018 03:27 amThe 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.
The centre hub has a module such that [...] the inner lab remains stationary.
... 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. ...
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)
Quote from: whitelancer64 on 10/31/2018 07:00 pmWould 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 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.
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. :-(
Quote from: mikelepage on 11/01/2018 03:53 amOne 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'm remodeling my house right now, and it's no fun being in a dwelling that is not finished...
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.
QuoteI'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.
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.