Artificial Gravity Habitats

[AngelLestat]

Just use a tether+counter weight to get artificial gravity.. 

But if we use artificial gravity (any kind) we are giving up having a better radioactive passive shielding against sun particles.

[fredinno]

3 hours ago, cubinator said:

That's probably what will happen. The first small missions will probably use non-rotating inflatables. The wide spinning ship is probably 2100s material.

Or something like Natuilius X.

[K^2]

28 minutes ago, fredinno said:

Or something like Natuilius X.

Nautilus X is inherently limited. It's better than microgravity on longer missions, but it's not good enough for a permanent settlement in space. The fundamental problem with centrifugal gravity is that human anatomy is pretty good at detecting rotation and isn't happy with it. In a large section of population, problems start to occur at mere 2RPM. If you have a trained crew, you can push it to 5RPM, but past that, you are likely to start having issues even with them. At 5RPM, you need a ring 70 meters in diameter. That's too large for a ship we're likely to build in any foreseeable future.

Nautilus X demonstrator module for ISS was meant to have 40 foot diameter and spin at up to 10 RPM. Even then, it could only generate 1/2 Earth's gravity. However, the main idea behind that is to have a ship with mere 5RPM that can generate roughly Moon's gravity in its habitat module, drastically reducing the negative side effects of low gravity the crew would suffer otherwise. This is not an environment you can permanently live in without developing serious health problems, but it is an environment you can suffer for over a year during, say, a Mars fly-by mission.

In contrast, if we go back to the idea of building a permanent outpost, you really do have to cut it down to 2RPM and ramp up gravity to 1g in order to allow general population to live there. If you were to build it as a ring, it would be nearly 1/2 kilometer across. This isn't some crazy science fiction, and if we absolutely had to build something like this, we actually can. But it's orders of magnitude beyond what we can afford with current space exploration budgets. That's where tethered designs come in. They don't require you to build a habitat ring kilometers long. They simply require a habitat module and a counterweight module. In many designs, counterweight contains all of your power generation/collection systems. Even if counterweight ends up lighter and has to extend further out from the rotation center, it's not a huge deal. A 1km long suspension cable we can do. Especially in the windless environment of space.

So realistically, if we are going to build a station with artificial gravity, the first one will be something like this. It will have a hub module with docking ports near the middle. It will have a habitat and counterweight or two habitat modules connected by long cables. And it will have a small elevator/airlock module that will be able to ride between the modules on these cables. Gentle rotation of the hub can easily be matched by any docking ship, and the elevator module will make it easy to transfer crew and supplies between modules. No complicated bearing mechanisms necessary, since the whole thing spins, including any ships that happen to be docked.

In theory, a structure like this can even be expanded, with additional pairs of habitat modules added suspended from the hub. And potentially, it could even grow into a full ring over time. Not that I expect the very first station to serve long enough for this to happen.

[Atlas2342]

So bigger or faster?

[Camacha]

10 hours ago, cubinator said:

That's probably what will happen. The first small missions will probably use non-rotating inflatables. The wide spinning ship is probably 2100s material.

You can easily build a spinning ship that is not too big. If you build an inhabited module on one end of a long stick and something else that is about as heavy on the other, you can have a baton style gravity ship. You could even do something like that with the existing capsules.

It is not huge spinning ship or bust

Edited February 11, 2016 by Camacha

[Atlas2342]

How about a Hermes-esque rotating hab? Would it work?

11 hours ago, K^2 said:

Nautilus X is inherently limited. It's better than microgravity on longer missions, but it's not good enough for a permanent settlement in space. The fundamental problem with centrifugal gravity is that human anatomy is pretty good at detecting rotation and isn't happy with it. In a large section of population, problems start to occur at mere 2RPM. If you have a trained crew, you can push it to 5RPM, but past that, you are likely to start having issues even with them. 

I could imagine dizziness and stuff like that but what other problems would the crew experience?

[p1t1o]

43 minutes ago, Atlas2342 said:

How about a Hermes-esque rotating hab? Would it work?

I could imagine dizziness and stuff like that but what other problems would the crew experience?

With rings beneath a certain [quite large] size, there perceived force of gravity will be different between your feet and your head - stronger at the feet than at the head, basically tidal forces - and this will be seriously uncomfortable. I'm not sure how it manifests, but I think it causes problems with balance, blood pressure, blood "pooling", nausea etc.

[Atlas2342]

How about not making gravity, gravity? Magnetic shoes anyone? Oh wait......

[fredinno]

14 hours ago, Atlas2342 said:

So bigger or faster?

 

13 hours ago, Camacha said:

You can easily build a spinning ship that is not too big. If you build an inhabited module on one end of a long stick and something else that is about as heavy on the other, you can have a baton style gravity ship. You could even do something like that with the existing capsules.

It is not huge spinning ship or bust

 

7 hours ago, Atlas2342 said:

How about not making gravity, gravity? Magnetic shoes anyone? Oh wait......

 

20 hours ago, K^2 said:

Nautilus X is inherently limited. It's better than microgravity on longer missions, but it's not good enough for a permanent settlement in space. The fundamental problem with centrifugal gravity is that human anatomy is pretty good at detecting rotation and isn't happy with it. In a large section of population, problems start to occur at mere 2RPM. If you have a trained crew, you can push it to 5RPM, but past that, you are likely to start having issues even with them. At 5RPM, you need a ring 70 meters in diameter. That's too large for a ship we're likely to build in any foreseeable future.

Nautilus X demonstrator module for ISS was meant to have 40 foot diameter and spin at up to 10 RPM. Even then, it could only generate 1/2 Earth's gravity. However, the main idea behind that is to have a ship with mere 5RPM that can generate roughly Moon's gravity in its habitat module, drastically reducing the negative side effects of low gravity the crew would suffer otherwise. This is not an environment you can permanently live in without developing serious health problems, but it is an environment you can suffer for over a year during, say, a Mars fly-by mission.

In contrast, if we go back to the idea of building a permanent outpost, you really do have to cut it down to 2RPM and ramp up gravity to 1g in order to allow general population to live there. If you were to build it as a ring, it would be nearly 1/2 kilometer across. This isn't some crazy science fiction, and if we absolutely had to build something like this, we actually can. But it's orders of magnitude beyond what we can afford with current space exploration budgets. That's where tethered designs come in. They don't require you to build a habitat ring kilometers long. They simply require a habitat module and a counterweight module. In many designs, counterweight contains all of your power generation/collection systems. Even if counterweight ends up lighter and has to extend further out from the rotation center, it's not a huge deal. A 1km long suspension cable we can do. Especially in the windless environment of space.

So realistically, if we are going to build a station with artificial gravity, the first one will be something like this. It will have a hub module with docking ports near the middle. It will have a habitat and counterweight or two habitat modules connected by long cables. And it will have a small elevator/airlock module that will be able to ride between the modules on these cables. Gentle rotation of the hub can easily be matched by any docking ship, and the elevator module will make it easy to transfer crew and supplies between modules. No complicated bearing mechanisms necessary, since the whole thing spins, including any ships that happen to be docked.

In theory, a structure like this can even be expanded, with additional pairs of habitat modules added suspended from the hub. And potentially, it could even grow into a full ring over time. Not that I expect the very first station to serve long enough for this to happen.

Only problem with a tethered design is that you get a station difficult to dock to due to rotation, unless you have a hinge, motor, and a "node" at the center, which would basically make this like a Nautilus-X with an oversized ring.

Also, 0G is a huge reason to go to space, so you'd also have a lot of non-rotated modules.

I was also thinking more near-term.

So the future is most likely to have hybrid space stations. a 1/2 km 2-3 m diameter narrow "hallway" with HAB quarters at each end, (possibly with a rail to make transportation through it faster) but most of the rest of the station in inflatable 0G modules.

[K^2]

6 minutes ago, fredinno said:

Only problem with a tethered design is that you get a station difficult to dock to due to rotation, unless you have a hinge, motor, and a "node" at the center, which would basically make this like a Nautilus-X with an oversized ring.

I have explicitly addressed docking and how it works without any moving parts with a tethered design. That was the emphasis on an entire paragraph. That is a big part of the reason why I'm calling for such a design. There is a difference between skimming a long text, and replying without even reading.

[fredinno]

10 hours ago, K^2 said:

I have explicitly addressed docking and how it works without any moving parts with a tethered design. That was the emphasis on an entire paragraph. That is a big part of the reason why I'm calling for such a design. There is a difference between skimming a long text, and replying without even reading.

Sorry.

[Atlas2342]

Do we have cables strong enough to handle the load?

[p1t1o]

1 hour ago, Atlas2342 said:

Do we have cables strong enough to handle the load?

The load will only be the mass of your rotating modules multiplied by whatever force of G you are generating, as your induced G will probably be some fraction of Earth-G then the force on your cable will be some fraction of the modules Earth-surface-weight. So yeah, I think we have cables strong enough to build a decent sized rotator, since we have cables strong enough to do this:

https://en.wikipedia.org/wiki/File:TAISUN_with_SCARABEO_9.JPG

 

14 hours ago, K^2 said:

I have explicitly...etc

...bit much dude, bad day?