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What if we spun up a solid Iron-Nickel asteroid such that it experienced an outward centrifugal force sufficient to simulate Earth or Mars gravity, and suppose we enclosed such an asteroid in a transparent gas bag that was sufficient to contain a 1-bar atmosphere of breathable gases?
Now we are too lazy to build a full-fleged O'Neill habitat or cylinder, so we just spin up a solid asteroid instead, let all the loose chunks and pieces fly off of it until we have left a solid core of asteroid that is in one piece and capable of holding itself together. The asteroid should be made to spin along the plane of the ecliptic and a mirror would then reflect sunlight towards one of the poles of the asteroid. We would then carve out ledges along the sides of the asteroids so we can build houses and do are gardening for human habitation.
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No-ones doing anything to my asteroids without my permission.
Anyway, you would use metal asteroids sa source of metal for habitats on other asteroids.
Use what is abundant and build to last
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I was thinking of the smallest body one might "terraform" in the traditional sense. That means placing the atmosphere on the outside of the asteroid. Since asteroids are small, this is feasible in the near future. The idea is simpy this, you create a balloon that contains a breathable atmosphere and you envelope an asteroid with it, then place an airlock on the outside of the balloon. Either a spaceship might dock with the outside of the atmospheric envelope or if the ship is small enough, it might be cycled through the airlock and into the interior. An asteroid that is 200 meters in diameter would have to rotate about 3 time per minute in order to create a 1g environment for people clinging onto its sides. This would work well if the asteroid was somewhat flattened. We'll call its axis of spin the "Equator" though I'm not in anyway pretending that this asteroid is in any way a ball or a sphere. Probably ball-shaped asteroids would be the worst candidates for this because that would mean the asteroid was made of alot of loose material held together by its weak gravity.
Consider this for a moment: Say you picked up a rock the size of your fist and you spun it on its axis so that it experiences 1g centripedal force on some of its outer extremities along its axis of spin. Does the rock break apart? Probably not. Now imagine this same exercise being performed on a boulder the size of your car. I'm sure there are plenty of boulders this size that will not break apart under their own weight when spun this rapidly. I'm sure that among the asteroids their are also boulders around 200 meters in diameter and larger that can be spun for gravity yet will not break apart under the stress. What we want is a flattened boulder at least 200 meters in diameter that provides a surface to cling to for human habitation and to support an ecology clinging to the side of a cliff. The gas bag or balloon can be held fast to the asteroid by counter-rotation cables attached the the "poles" of this asteroid/boulder. Also the gas bag only needs to be transparent perpendicular to the asteroids plane of spin as the sunlight is going to be reflected by a space mirror to hit the side of the asteroid. Also a cyclonic air current will have to be induced such that the movement of the air around the asteroid approximately matches the spin of said asteroid, but like a cyclone the air spins fastest in the vicinity of the asteroid and gradually slows down the further outwards one travels until one reaches the surface of the gas bag or balloon.
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What if we spun up a solid Iron-Nickel asteroid such that it experienced an outward centrifugal force sufficient to simulate Earth or Mars gravity, and suppose we enclosed such an asteroid in a transparent gas bag that was sufficient to contain a 1-bar atmosphere of breathable gases?
Now we are too lazy to build a full-fleged O'Neill habitat or cylinder, so we just spin up a solid asteroid instead, let all the loose chunks and pieces fly off of it until we have left a solid core of asteroid that is in one piece and capable of holding itself together. The asteroid should be made to spin along the plane of the ecliptic and a mirror would then reflect sunlight towards one of the poles of the asteroid. We would then carve out ledges along the sides of the asteroids so we can build houses and do are gardening for human habitation.
Not a very efficient habitat, considering the very limited living space gained for the massive investment required in building and maintaining a several kilometre wide gas bag and of course the energy needed to rotate a billion tonne asteroid in the first place.
It isn't just a case of whether or not it is technically possible, but whether it is desrable compared to the alternatives.
An O'Neill sphere capable of housing 10,000 people would weigh in at less than 100,000 tonnes without shielding. You could probbaly build them even smaller with compact architecture.
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Lets consider the alternatives then. A kilometers wide gas bag is liable to be less massive than a manufactured kilometers wide O'Neill habitat. In the second case the whole habitat rotates and the walls of the habitat not only has to be strong enough to hold in all the air, but also the weight of all that shielding, the slag, rock, and concrete, the water, the soil, the plants, people and all the buildings people choose to live in on the inside of the habitat.
With the asteroid, you start by rotating the asteroid, other than the gas bag, there is very little else to bring. The asteroid is already there, nature provides it. To get the right orbit, you just pick the right asteroid, no moving of billions of tons of rock. To spin it up, you need only the most efficient of propulsion systems, an ion rocket, or perhaps an array of solar sails, very little reaction mass is expended, and the Sun provides all the energy you need. I'd say you spin up the asteroid first and see what breaks off or falls off, and when the asteroid is done falling apart you get a solid chunk that can hold itself together, you then bring or manuacture the gas bag. The gas bag isn't that massive relative to its volume, it doesn't even have to rotate. There is a hole and a flap in the side of the gas bag that is large enough to admit entry of the spinning asteroid.
Once the asteroid is inside, the flap is closed and sealed, with an airlock and docking port attached. The bag is then pressurize inflating to its full volume and as gas is produced or delivered the gas pressure increases until it reaches full sea level air pressure on Earth. What about the minimal living area, much depends on the original shape of the asteroid. If the asteroid is round, then there is not much to cling to, if it is in the shape of a dumbbell, that would be much better, there are many asteroids to choose from, I'm sure if we searched through them, we would eventually find one whose shape served our purpose. That is just the start however, as settlement activity increased, we could carve out further space inside. With an O'Neall, the whole entire habitat basically has to be finished before people can start moving in.
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Lets consider the alternatives then. A kilometers wide gas bag is liable to be less massive than a manufactured kilometers wide O'Neill habitat. In the second case the whole habitat rotates and the walls of the habitat not only has to be strong enough to hold in all the air, but also the weight of all that shielding, the slag, rock, and concrete, the water, the soil, the plants, people and all the buildings people choose to live in on the inside of the habitat.
With the asteroid, you start by rotating the asteroid, other than the gas bag, there is very little else to bring. The asteroid is already there, nature provides it. To get the right orbit, you just pick the right asteroid, no moving of billions of tons of rock. To spin it up, you need only the most efficient of propulsion systems, an ion rocket, or perhaps an array of solar sails, very little reaction mass is expended, and the Sun provides all the energy you need. I'd say you spin up the asteroid first and see what breaks off or falls off, and when the asteroid is done falling apart you get a solid chunk that can hold itself together, you then bring or manuacture the gas bag. The gas bag isn't that massive relative to its volume, it doesn't even have to rotate. There is a hole and a flap in the side of the gas bag that is large enough to admit entry of the spinning asteroid.
Once the asteroid is inside, the flap is closed and sealed, with an airlock and docking port attached. The bag is then pressurize inflating to its full volume and as gas is produced or delivered the gas pressure increases until it reaches full sea level air pressure on Earth. What about the minimal living area, much depends on the original shape of the asteroid. If the asteroid is round, then there is not much to cling to, if it is in the shape of a dumbbell, that would be much better, there are many asteroids to choose from, I'm sure if we searched through them, we would eventually find one whose shape served our purpose. That is just the start however, as settlement activity increased, we could carve out further space inside. With an O'Neall, the whole entire habitat basically has to be finished before people can start moving in.
You could equally argue that all of the materials needed to build an o'neill habitat are already there. If you are happy with the location, very little extra energy is needed to lift the materials out of the asteroids limited gravity well and construct whatever habitat you want. Solar power can provide the heat needed to melt the metal and glass that you need.
The problem with a spinning gas-bagged asteroid as far as I can see is that little useful surface area is available and to create it one must carve out caves and ledges from solid stainless steel. If we take this idea to its logical limit and maximimise the internal surface area through extensive digging, then we have a hollowed out asteroid that looks very much like ........an O'neill habitat.
So the question is, do we mine the asteroid and use the materials to build a habitat, or do we try to achieve the same thing by carving out a natural stainless steel asteroid and encasing it in a bubble?
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The latter involves less processing of material, the structure of a hollowed out asteroid is what's left behind, while the structure of an O'Neill colony is what's dug out of the asteroid.
Consider this: You can live in the cavity of a partially hollowed out asteroid and as the population increases, you can dig out some more. Leaving aside the external gas bag, you can pressurize the hollowed out interior. As for spinning the asteroid, some asteroids may be spinning fast enough already. There are hundreds or thousands of asteroids if not millions, they've probably undergone some collisions, and some solid fragments while quite sizable may be spinning quite rapidly. Perhaps its not so much the spinning up of an asteroid as much as a systematic search of the asteroid belt and near Earth asteroids looking for just the right type spinning at the right rate, If we can find that asteroid, we could move right in! I'm not sure if that asteroid exists, but seeing how there is so many in the Solar System, it just may. If it is close enough, we could visit it perhaps using the spaceships we develop for travel to Mars or if close enough, the Moon. We don't have to manipulate large masses if we find just the right asteroid, it may be a matter of statistics and asteroid detection.
The ability to mount a manned expedition to Mars implies a similar capability of sending men to an asteroid. While Mars gets all the glory, an expedition to Mars has a potential side benefit of opening up manned expeditions to the asteroids. Whereas you can set up a dome on Mars, you can bag an asteroid using a similar material.
Another thing to consider is this: Asteroids initially provide plenty of radiation shielding, all you have to do is dig out the tiniest of tunnels deep enough, and you've got the whole bulk of unprocessed asteroid material to protect you from solar flares and cosmic rays. Think of it this way, the conventional inhabitation of space leading to an O'Neill colony starts out with "tin cans" in orbit, aluminum frame assemblies much like what the International Space Station is to day. As your population gets bigger, you build more "tin cans" and add on to a "tinker toy" like structure of aluminum air frames, all of which provide very little protection from radiation by themselves, but you can send a crew of 6 to an asteroid that is miles wide, and in fact about the same size as those proposed O'Neill colonies, and much more massive as they are solid rock as opposed to to wheels, hollow spheres, or hollow cylinders. With the right sort of equipment a crew of six could dig right into that asteroid and make a home for themselves, need more room, they can dig some more, add more people and they dig some more. With an O'Neill colony, you need something like about 10,000 people already living in space to even begin the construction of such a colony, and probably only one that "just fits" such a crowd would be the one that is built, if more people come you have to build more structure rather than digging out of the structure that is already there.
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Hello, anyone there? Spinning an asteroid would just fling you off.
Use what is abundant and build to last
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Hello, anyone there? Spinning an asteroid would just fling you off.
Not unless you are in the habit of standing on ceilings.
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So you want to hollow it out and live on the inside. Then what is the point of the gasbag? Just make the asteroid airtight with the waste materiels, add an airlock... congratulations, you have an o'neill habitat. With thicker walls for radiation protection.
Use what is abundant and build to last
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You may be right, it was a thought experiment on what's the smallest body you can terraform. The choices are either the bag spins with the habitat or it doesn't. If it doesn't what's the keep the asteroid spinning as air drag will tend to slow it down. If the air and bag spins with the asteroid, every now and then chunks of the asteroid may break off due to the tunneling activity and very likely fall to the air bag memberane and puncture it. On the other hand an airbag may be more airtight than a rock. If the airbag is not much bigger than the asteroid, it might connect to the asteroid at the poles, and it would help the asteroid contain its gasses. Even in a vacuum, there is always the danger of extending the tunnel in the asteroid too far and breaking the air tight seal within the asteroid.
I think a spinning asteroid is likely to be compartmentalised into a series of air tight chambers connected by airlocks. Sunlight can come in through shafts from the center of the asteroid, there would likely be a hole drilled through the poles of the asteroid, where one side you can dock with and the other side where a mirror would focus sunlight into which would them be directed to the air tight chambers in the rim. The asteroid would not likely be one hollow shell such as an O'Neill, as the structure is made of rock, not of tempered steel, and some allowances need to be made for weaknesses in the structure of the body to allow for thicker walls and supporting layers of rock.
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DPS: Sending humans to an asteroid?
http://www.planetary.org/blog/article/00001184/
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An interesting question is exactly how much of a "sample" could they return to Earth? Does the "Sample" actually have to fit inside the spacecraft?
One possibility is that they could have an asteroid sample that's actually larger than the Orion Spacecraft and return that to Earth placing it in a highly elliptical orbit around the Earth whose low point is just above the top of Earth's atmosphere. Then NASA could launch an Ares V spaceship to maneuver this asteroid chunk so that it matches the Orbit of the International Space Station and then have scientists onboard the Space Station examine this "Sample" further. They could do experiments with it such as material processing. Perhaps the asteroid chunk could eventually be attached to the space station and maybe some of its material could be used for radiation shielding.
This borders on actual Asteroid mining doesn't it. Well the gravity of an asteroid is negligable, the main trick is changing the orbit of as large a chunk of the asteroid as we can manage and placing it in orbit around Earth. If NASA successfully mines an asteroid with Constellation equipment, this might oprn up some commerical opportunities.
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