I think this should have included the currently most advanced manufacturer of inflatable (though not round/rotating) space modules: Sierra Space.
See e.g. https://www.theverge.com/2024/7/25/24206219/nasa-sierra-spac...
Inflatable Space Stations
31–40 of 50 posts
Re: Inflatable Space Stations
#32Love the painting of the huge toroidal space station—with the houses and forests inside. I had a thought experiment: if you could ride a bicycle (motorcycle?) against the direction of spin of the station you would essentially be "stationary". You would still have a velocity into the always-sloping-up wheel. What if you rode up a gentle ramp? Could you break away from the surface of the wheel then and become "weightle…
Important to note that while the station has angular velocity it is not usually accelerating.
If you decelerate and cancel your own angular velocity relative to the station hub, you do indeed simply stop experiencing gravity.
Imagine instead jumping off the 'stationary' hub of a rotating station. You simply float under no gravity until you hit the ring. The angular velocity imparted on you by the ring is the gravity you perceive. But once you have that angular velocity, you can jump from the ring's inner surface and fall back down as if the gravity were real.
One way such stations are imagined in media is with a spiral ramp from the surface of the ring up to the hub. It works just like you expect. You gradually shed your angular velocity by climbing the 'gravity well'.
Re: Inflatable Space Stations
#33I never understand why the rotating station concepts seem to all have rigid tethers, either in the form of a central boom or a rigid circular structure. It would seem like you could get a much larger diameter, so less rotational velocity and more comfort, by attaching rigid, or inflatable in this case, structures with a tether. Compressive loads are non existent, you just need to resist tensile loads. Maybe I'll go a…
There are compressive forces. If mass inside the ring is not balanced, it can drag the ring into an ellipsoid. The inner sides of the ellipse are compressed.
A rigid ring can resist some of this inherently, but a rigid spoke to the hub cleanly takes up all the inward forces.
If your ring is not rigid, any perturbations can cause oscillations that throw the whole thing out of balance. Like a gas leak in one compartment adding thrust at a weird angle. Soon the whole ring will be oscillating along its plane, which is obviously bad. You can actively correct with thrusters on each segment, but that's a lot of extra complexity.
Basically it's all about stability. A big rigid object is much harder to shake apart. A metal circle will stay a circle in a lot more circumstances than a circle of rope will. Doubly so when rotating in zero gravity.
Flexible tethers are mainly good for small scale. Swinging a crew capsule about a big mass (Project Hail Mary, Stardancer) is indeed cheap and easy. With the complication that you must completely spin down to maneuver or dock.
Re: Inflatable Space Stations
#34I suspect without ISRU production of bulk orbit sheet metal, the most feasible solution is to repurpose rockets in their whole. Building a station this large is gonna be costly even within the cargo hold of starship. But six of them, gutted of insides as welded end to end could provide the vast majority of the bulk mass. This assume rather sophisticated orbital welding and object manipulation; but its feasible we cou…
aren't rockets like the starship almost the opposite of what you want in a space station? They want to minimize the integrity of the rocket as much as possible (without blowing up) to reduce the mass while for a station you want robustness (for pressure & impacts).
Starship tanks likely hold several bars of pressure and survive transportation to orbit...
Re: Inflatable Space Stations
#35Anything that can be inflated can usually be deflated.
They are one time inflated, become rigid afterwards to withstand meteoroids, I think.
Re: Inflatable Space Stations
#36Earlier quoted context omitted.
aren't rockets like the starship almost the opposite of what you want in a space station? They want to minimize the integrity of the rocket as much as possible (without blowing up) to reduce the mass while for a station you want robustness (for pressure & impacts).
Starship tanks likely hold several bars of pressure and survive transportation to orbit...
That is actually with the caviat that the internal pressure help structurally a bit. But that is still plenty for a gentle rotation in otbit and 1 bar of pressure.
And if the plan is to do this; you want to prepare the rocket for this purpose anyway so nothing stops you from making a thicker wall and sacrificing payload capacity since the hull is the payload.
Re: Inflatable Space Stations
#37I suspect without ISRU production of bulk orbit sheet metal, the most feasible solution is to repurpose rockets in their whole. Building a station this large is gonna be costly even within the cargo hold of starship. But six of them, gutted of insides as welded end to end could provide the vast majority of the bulk mass. This assume rather sophisticated orbital welding and object manipulation; but its feasible we cou…
> repurpose rockets in their whole
Reminds me of a short sci-fi story:
> The engines are part of the orbiter, so they can be brought home and reused. The solid boosters drop off minutes after liftoff and are recovered for refurbishment. Even the unmanned heavy-lift cargo launchers use the same basic system. But until our group came along, the huge external tanks were simply dumped, after fueling the shuttle to almost orbital velocity.
> [...] The main purpose of the design is simply to keep the tanks from falling. The two massive ends of the Farm act like a dipole in the gradient of the Earth's gravitational field, so each deck winds up orbiting edge-forward, like a flat plate skimming. This reduces the drag caused by the upper fringes of the atmosphere, extending our orbital lifetime.
Re: Inflatable Space Stations
#38Earlier quoted context omitted.
I thought most asteroids were basically just gravel piles loosely held together by internal gravity?
If we're talking about objects in the asteroid belt, the internal consistency varies wildly. Most smaller objects are indeed rubble piles: boulders, pebbles, and sand-like grains, down to dust. As you'd expect, they're very weak structurally. Notably, the OSIRIS-REx probe was nearly swallowed by its loose material during the sample collection on Bennu. Some of the other large, iron-rich asteroids like Ceres, Vesta, P…
Your claim about Bennu fascinated me...
"The spacecraft risked being swallowed whole by the asteroid as it collected the sample. As OSIRIS-REx touched the ground in October 2020, pebbles began flying about. The timely ignition of its thruster kept it safe and led to the creation of a puzzling large crater 8 meters (26 feet) across." https://www.iflscience.com/nasas-osiris-rex-was-almost-swall...
Wow.
Re: Inflatable Space Stations
#39Re: Inflatable Space Stations
#40This has been suggested before for a permanent station "on" Venus, floating in its atmosphere.
The atmosphere is caustic, but that's just a design material issue. By maintaining a positive pressure, small punctures would just be a loss to O2 supplies; crew wouldn't need any special safety equipment to patch the holes.
Energy could be obtained via solar, chemical engines, or both. Temperature could be controlled by hovering at a spot near the day/night horizon; since the day sid is too hot and the night side too cold, there exists a Goldilocks region.
Venus is generally closer than Mars, with a weak magnetic field that would help reduce radiation (along with the atmosphere).