[Space] What if we sent an "artificial planet" to space?

[windows_x_seven]

Hi.

I've been thinking, what if we sent an "artificial planet" to space, and leave it there for a couple of million years (stable orbit)?

By artificial planet, I mean a sphere with an iron core, things like our planet has, an atmosphere with similar gases to our own, 24 hour day/night cycle (spinning), you know. (EDIT: As in "sphere" and "artificial planet", I do NOT mean a thing as big as our planet. A 3 or 5 meter sphere is what I have on mind.)

Do you think that that would be an useful experiment about finding out the beginning of life, or another subject?

Please leave a comment.

(also, that double subject thing, that was on purpose.)

Edited March 19, 2015 by windows_x_seven
Added stuff.

[FishInferno]

I would like to know how to build said planet

[RainDreamer]

I think it would be more useful to just find a planet with similar characteristics that you describe, rather than creating one our own. If we are capable of creating such things, humanity has been so far advanced in technology that I suspect people already figured out the origin of life.

Unless you mean a cube sat-sized planet. In which case I doubt it has enough mass to hold its own atmosphere. Even the moon only has microscopic atmosphere. So maybe a sealed environment with artificial atmosphere...but then we might as well direct that kind of research toward creating sustainable bio domes for long term travel through space.

Edited March 19, 2015 by RainDreamer

[Robotengineer]

If it were possible, it might be an interesting idea. However the sheer size, millions of years timespan, and the fact that we don't know how to build a planet makes it impossible*.

*Impossible with current or even predicted future technology.

[windows_x_seven]

By planet, I don't mean one as big as ours.

A 3m, or 5m sphere is what I was thinking about because of rocket sizes.

If the object won't generate enough gravity to hold onto it's atmosphere, what about using glass in a spoke-and-wheel way?

And about building it, it could be done by astronauts or robots. But adding water, dirt and air to it would have to happen in a zero-g environment, however how to do it if a glass dome is used? Split it?

Edited March 19, 2015 by windows_x_seven

[peadar1987]

A 3m sphere would have negligible gravity, and not be able to hold onto an atmosphere, keep a liquid core, maintain a magnetosphere, etc. I doubt we'd learn anything from it.

[windows_x_seven]

A 3m sphere would have negligible gravity, and not be able to hold onto an atmosphere, keep a liquid core, maintain a magnetosphere, etc. I doubt we'd learn anything from it.

Physics seems to have punched me.

Glass dome and magnetic rocks/metals?

[RainDreamer]

Will still need basic building blocks of life like water and all the other chemicals. And holding them all in a container with neligible gravity...I think we are just going to have a very fancy slush of random stuff in an orb.

It would be just better that we build a flat surface biome in a climate controlled container inside a shielded satellite so that radiation doesn't just kill whatever comes up from our primordial soup plate. But if we are doing all that shielding, doing the same thing on earth is probably easier.

[Slam_Jones]

I'm trying to imagine how such a small object can have enough gravity to keep an atmosphere in place. It'd have to have some strong electro-magnets to keep it from flying into space, simulating Earth's magnetic field.

Without the magnetic field, Earth becomes Mars, and mini-planet does nothing interesting, since solar winds would strip away any unshielded atmosphere.

You'd also need a few different chemical reactions going on in the "core" to produce the right elements, etc.

Edited March 19, 2015 by Slam_Jones

[windows_x_seven]

Will still need basic building blocks of life like water and all the other chemicals. And holding them all in a container with neligible gravity...I think we are just going to have a very fancy slush of random stuff in an orb.

It would be just better that we build a flat surface biome in a climate controlled container inside a shielded satellite so that radiation doesn't just kill whatever comes up from our primordial soup plate. But if we are doing all that shielding, doing the same thing on earth is probably easier.

Well... looks like it's pointless, then.

Anyways, thanks for your comments.

[stupid_chris]

At this point you're basically proposing to send a round ISS in orbit.

[RainDreamer]

At this point you're basically proposing to send a round ISS in orbit.

No, it is a Death Star.

[Sampa]

there appears to be one serious problem with your theory. Gravity. How would you suggest we give this artificial planet its gravity to maintain its atmosphere? centrifugal force? I think not. That would only throw off its atmosphere. Also, space dust would easily start to slow its rotation down. Forgive me for being blunt, but I say it like I see it!

[Kerbart]

Wouldn't it be much easier to put a glass dome on earth with all the "ingredients" in it, sterilize it and seal it off?

[vger]

This sounds like a job for a "Genesis Torpedo," or the more practical equivalent.

As RainDreamer said, you're better off just going out to find a 'dead' body that fits your specifications, and then "terraform" it. You'll save a lot of time and effort, and won't need 10,000,000,000 dV to get the iron into orbit.

I'm trying to imagine how such a small object can have enough gravity to keep an atmosphere in place. It'd have to have some strong electro-magnets to keep it from flying into space, simulating Earth's magnetic field.

What if it was heavily-compated iron?

Bit of a tangent, but I've always wondered if compressing matter into a small enough space (without ending up with a singularity) could create a planetary core with a gravity well strong enough to have an asteroid-sized rock with a stable atmosphere comparable to 1atm.

Also curious if this could occur naturally, if the solar system contained enough heavy elements while it was forming. For instance, if Earth had a core made of uranium instead of nickel-iron. Granted, that would probably be a very radioactive place, but I'm just thinking in terms of an atmosphere at all, not a habitable world by human standards.

Edited March 19, 2015 by vger

[WestAir]

Giving the "million years" timescale, a computer simulation might prove more fruitful.

[PB666]

No, it is a Death Star.

Death Star did not have a filled metal interior. If you hurled a 5 meter iron object at a death star it would likely go through with a nominal loss of velocity.

[magnemoe]

This sounds like a job for a "Genesis Torpedo," or the more practical equivalent.

As RainDreamer said, you're better off just going out to find a 'dead' body that fits your specifications, and then "terraform" it. You'll save a lot of time and effort, and won't need 10,000,000,000 dV to get the iron into orbit.

What if it was heavily-compated iron?

Bit of a tangent, but I've always wondered if compressing matter into a small enough space (without ending up with a singularity) could create a planetary core with a gravity well strong enough to have an asteroid-sized rock with a stable atmosphere comparable to 1atm.

Also curious if this could occur naturally, if the solar system contained enough heavy elements while it was forming. For instance, if Earth had a core made of uranium instead of nickel-iron. Granted, that would probably be a very radioactive place, but I'm just thinking in terms of an atmosphere at all, not a habitable world by human standards.

You could imagine an mercury type planet with an huge iron core and just an thin rock layer because you hit an larger body, some claim that mercury was the body who hit earth and created the moon.

Yes it had to be larger say 0.4-0.5 g to hold atmosphere, this is rare but not implausible.

More fun if you found an miniature black hole you could build an roof around it who would be ground. However it had to have an decent mass, moon equivalent would probably work, your problem is that if its too small you would get 1g at ground however gravity would tapper off very fast so the upper atmosphere would have less gravity and could easy escape.

Same is true for iron planets so they would lose air faster than Mars with 0.3g, anybody know how small you could get?

Way easier to make an giant rotating space station it could easy be large enough to have an working ecosystem and its far more practical as you have 0g in center and its no issue to dock with.

[Vanamonde]

It wouldn't end well.

[dbmorpher]

Assuming we did create a small ecosystem in space and just let it sit for millions of years it wouldn't have the influx of resources the earth got from comets and asteroids, also in such a small ecosystem there wouldn't be enough organisms for evolution to occur past a microscopic scale. Even then the population size makes it very vulnerable for complete extinction.

[peadar1987]

Bit of a tangent, but I've always wondered if compressing matter into a small enough space (without ending up with a singularity) could create a planetary core with a gravity well strong enough to have an asteroid-sized rock with a stable atmosphere comparable to 1atm.

Also curious if this could occur naturally, if the solar system contained enough heavy elements while it was forming. For instance, if Earth had a core made of uranium instead of nickel-iron. Granted, that would probably be a very radioactive place, but I'm just thinking in terms of an atmosphere at all, not a habitable world by human standards.

Well acceleration due to gravity is given by g=GM/(r^2). G is a constant (6.7E-11), M is the mass of your body, and r is the distance from the centre. If r is 100km, M is 1.5E21kg. Our sphere has a volume of 4.2E15m^3, so our density would have to be 35700kg/m^3. The densest substance we know of is Osmium, with a density of 22590kg/m^3. The density of the earth is 5510kg/m^3.

Luckily, the Schwarzschild Radius for such a mass is 0.000002m (according to this), so your planet wouldn't collapse into a black hole at least.

Rearranging the equation for acceleration due to gravity and replacing the mass of the body with the volume of a sphere multiplied by the density of Osmium, we get:

g=G*((4/3)*PI*r)*DENSITY

Setting g to 9.8, as on earth, we get, for a planet the density of Osmium, a radius of 1,580,000m. This is about a quarter the radius of earth (slightly smaller than the moon), and is, as far as we know, the smallest a planet can be and still have earth-like gravity. (In reality, it would probably be a bit smaller, as the Osmium would compress and become denser. I don't have the expertise to work out a general solution for this, as it involves some tricky nonlinear maths as the density changes and pressures both feed back on each other)