Asteroid Habitat

[neilsox]

I like habitats at the mass center of asteroids. A small dimension of 50 to 100 meters may be ideal for the first attempt: These come closer to the Earth than the moon several times per year, so the trip can be made from the ISS to the asteroid in an unshielded ship in a few hours, instead of days. Ten hours at 25,000 miles per hour = 250,000 miles, and perhaps twice that average speed is possible without significant technology advances. It will be necessary to launch while the asteroid is almost a million miles before it's closest approach, and most of the delta v will be used to match the speed of the asteroid, so a soft landing can be made. Some asteroids will be too fast in the wrong direction, so the crew may need to stand by on the ISS for more than a year.
The craft should have a rocket engine at each end, so it can be held stationary on the asteroid surface while the lower engine burns it's way into the asteroid. Asteroids this small have only micro gravity. Hopefully about half the length of the ship is below the surface when the fuel is used up. It may take a day to cool to human tolerable temperatures. The rest of the way to the mass center will be human muscle with picks and shovel. If a seal between the space craft and hole is successful the work area can be pressurized with 99% oxygen. The back up plan is a 3 meter sphere which will be inflated at the mass center of the asteroid to serve as a extra room in addition to the space craft. Unless the asteroid has lots of radio active isotopes, the mass center has very low radiation exposure. If the asteroid is a gravel pile, it will be necessary to put bands around the outside as the gravity is not enough to keep even 4 psi of breathing air from expanding the asteroid to distruction. If the rendezvous fails, the spacecraft may have enough life support to land on a different asteroid, or return to Earth in about a year. By then the crew will have extreme radiation exposure, but they may live a few more years. I have more details, but your comments, please. Neil

 

[yevaud]

One proposed method of creating Asteroid habitats is to bore into the center of a nickel-iron body, emplace there a very large contained mass of ice, and then seal the hole back up. Rotate the asteroid about it's center of mass, and illuminate with thin mylar mirrors, concentrating sunlight on them.

Over time, the asteroid will become molten, and after a time, once the heat has reached the center, the mass of ice - now long melted - will finally explode spectacularly. It would inflate the molten mass of nickel iron into a large, hollow sphere, perfect for the creation of a habitat.

 

[Shpaget]

Over time, the asteroid will become molten, and after a time, once the heat has reached the center, the mass of ice - now long melted - will finally explode spectacularly. It would inflate the molten mass of nickel iron into a large, hollow sphere, perfect for the creation of a habitat.

Why would it explode? You need a lot of heat to evaporate water, and that heat wouldn't come at once, so water would slowly boil.
Also, chances are that the asteroid isn't perfectly spherical, so it wouldn't expand regularly and would start to leak somewhere, or even pop like a balloon.

 

[yevaud]

Sorry, but this is/was not my idea, I'm merely repeating it. However, it was variously noted by people at places such as the L5 Institute (many years ago) that this was feasible.

As to the explosion aspect, what does a contained gas do if severely heated and yet still contained past the physical limits of it's containment? Yes, a nice explosion.

 

[Saiph]

so...asteroid popcorn? I think it's feasable...but a bit optimistic.

and very neat

 

[yevaud]

Neat, yes.

Sometimes it's those wild-ass ideas that work best.

 

[kelvinzero]

You guys are all kidding right?

This is cartoon physics. It would work in worlds where crates of ACME dynamite are a common depilatory for coyotes

 

[yevaud]

Why wouldn't it work? A small expansive explosion at the center-of-mass of a molten chunk of nickel-iron? It'd inflate it like a balloon.

 

[Shpaget]

There are techniques for explosion molding, but it is used for shaping of sheet metals and a die is always used.
To use this method on something as asteroid, you would need to melt it completely to fuse all the chunks, expand it and cool it rapidly.
Let's say you have big enough mirrors to heat it up and you can figure out exactly how large your explosion you need.
How would you get that charge in the middle of giant lump molten iron? Remember, we're in space, cooling is serious problem, and you have millions of tons of liquid iron that will fry anything you send.
Even if you manage to do it, there is no guarantee that the asteroid is homogeneous, so the explosion will probably cause uneven expansion which will lead to either forming a small bubble on one side, near surface, or it will rip the asteroid apart.
So let's assume you did manage to heat it, get the explosive in the middle and that the detonation went perfectly.
You now have a bubble of molten iron. How long will it take it to cool down? Will it stay inflated long enough or will it collapse before it solidifies?

 

[yevaud]

That was all explained or at least blatantly implied.

 

[thnkrx]

In a different vein, this approach might make for a nifty (and much safer/cheaper) 'spaceship to Mars' type deal. Simply find an asteriod that makes the occasional 'close approach' to both Earth and Mars - maybe nudge one until it is in the 'correct' orbit. Set up your habitat at the asteriods center (maybe using some of the fancy robot stuff that gets mentioned now and again). At that point it is just a matter of getting from Earth to the Asteriod - which technologically should be no more difficult than getting from Earth to the Moon - and then kicking back until the Asteriod approaches Mars, at which point you depart. The thickness of the asteriod should stop all but the absolute nastiness of radiation, as well as various micometeors. Depending on the exact configuration of its interior, it might also be possible to 'spin' the asteriod to create artifical gravity that is medically acceptable with technology only slightly beyond todays.