3 ms·

4 rpm is about as fast as you can spin to avoid vertigo when turning your head. So for 1g that requires a diameter of 56 meters (about the size of the leaning t

4 rpm is about as fast as you can spin to avoid vertigo when turning your head. So for 1g that requires a diameter of 56 meters (about the size of the leaning tower of Pisa), which is big. Other challenges include how to spin it up (and down) safely, how to dock with non-spinning things, how to deal with changes in mass distribution, and how to put thrusters on it for use when it's spinning. None of these is impossible, but together they create a serious engineering problem, and the size of the whole thing is ultimately the dealbreaker.

jandrese 5y ago
The ISS is 109m end to end so a 56 meter diameter isn't an impossible dream. I've toyed around with a design that uses basically a shell around Starship that would be bolted together in orbit to form the station. I was aiming for 2 RPM however. Docking would be via a central hub. Ships would have to match rotation to dock, but it shouldn't be too hard. My conclusion is that if the money and/or political will were there we could start doing this today, but the project would be hugely expensive (even with SpaceX cutting launch costs to a fraction of what they were only a few short years ago) and once you have it built it will be looking for a purpose. It would be cool for people to basically commute up to the central part (via elevator) to do zero-g research stuff, then commute back to the ring to live and avoid the various health problems with long term zero-g living like bone density loss. You can even build a simple starter station that has only two segments on opposite sides of the central hub. This is less cool since you don't get the jogging path around the station. If stability is an issue you could also include a computer controlled mobile counterweight on the ends. I also had the concept of building it as a double hull with a layer of water between the inner and outer to reduce radiation flux and absorb micrometeorite impacts. But in the end you are still talking about a hugely expensive project that solves problems that aren't all that bad yet. About the only way I could see this being built is if Elon decides to go all in on space and liquidates his fortune to build it. The instant some annoying bean counters ask the question "is this the best way to spend this money" the project is dead.

jandrese 5y ago

The ISS is 109m end to end so a 56 meter diameter isn't an impossible dream. I've toyed around with a design that uses basically a shell around Starship that would be bolted together in orbit to form the station. I was aiming for 2 RPM however. Docking would be via a central hub. Ships would have to match rotation to dock, but it shouldn't be too hard. My conclusion is that if the money and/or political will were there we could start doing this today, but the project would be hugely expensive (even with SpaceX cutting launch costs to a fraction of what they were only a few short years ago) and once you have it built it will be looking for a purpose. It would be cool for people to basically commute up to the central part (via elevator) to do zero-g research stuff, then commute back to the ring to live and avoid the various health problems with long term zero-g living like bone density loss. You can even build a simple starter station that has only two segments on opposite sides of the central hub. This is less cool since you don't get the jogging path around the station. If stability is an issue you could also include a computer controlled mobile counterweight on the ends. I also had the concept of building it as a double hull with a layer of water between the inner and outer to reduce radiation flux and absorb micrometeorite impacts. But in the end you are still talking about a hugely expensive project that solves problems that aren't all that bad yet. About the only way I could see this being built is if Elon decides to go all in on space and liquidates his fortune to build it. The instant some annoying bean counters ask the question "is this the best way to spend this money" the project is dead.