The relevance of planets to an advanced civilization

[daniel l.]

When you consider the fact that, once hollowed out, asteroids are extremely versatile. Everything from agriculture to mass-inhabitation or industrial purposes.

Very rarely does a star system have habitable planets, but they all have asteroids, at least a few. Also, the radiation emitted by the star might prohibit humans from surviving in the open. Asteroids, on the other hand, can shield those who live in its interior.

Ultimately, colonizing an entire asteroid belt would be more practical than any single planet. Since each asteroid is separate from another by millions of miles, it is unlikely that any one calamity could destroy the entirety of a civilization that had an entire belt settled.

Trade between asteroids would actually be quite a bit easier than between asteroids or even between cities on a planetary surface. An Ion engine or a solar sail is all that's needed to cross the vast distances between them, making shipping an extremely inexpensive thing because little to no fuel is needed.

I believe that planets will be regarded primarily as the gems of space; pretty, but largely unimportant. The few habitable worlds in the galaxy might be designated as giant parks, or perhaps inhabited by people of importance, such as leaders of state.

Most of humanity will live inside asteroids. And no, it won't be anything like The Expanse. Automation will prevent such dark scenarios from happening.

[regex]

Sure, seems legit. Asteroids and small planetary bodies represent easily accessible resources once you're free of a planet.

But you should also realize that the crust of a planet with a breathable atmosphere represents far more easily accessible resources, once you're down there.

[Mitchz95]

Planets also account for the vast majority of a solar system's non-stellar resources. There's no way a space-faring civilization could turn down that much raw material.

[Bill Phil]

48 minutes ago, Mitchz95 said:

Planets also account for the vast majority of a solar system's non-stellar resources. There's no way a space-faring civilization could turn down that much raw material.

Sure, but so much energy is involved, and there's so many resources on lower gravity moons, that planets aren't that worth it. Of course, if you have enough energy to travel between stars, then mining out uninhabited planets isn't that hard.

OP:

Yeah, asteroids are good for resources, but they usually don't make good settlements. A bunch are just piles of rubble, and they can't handle too much rotation if you want to keep gravity around. Sure, you could just spin a cylinder inside and not the whole roid, but then you might as well just start mining  the asteroid and build the settlement near it. 

Not to say that there won't be colonies inside asteroids, or that it's a bad idea. The asteroid can provide ample shielding, as you mentioned. 

You don't even need to use an engine to move things around. At least not on the cargo vehicle. A good EM catapult, imparting just a little velocity, and aimed towards a "catcher" or something, will suffice. If the colonies are close to each other, you can even run a "train" between them.

[kerbiloid]

Is there a detailed list of asteroid resouces per asteroid?

[KSK]

How advanced a civilization are we talking about here?

If we're assuming access to some kind of FTL capability such that interstellar journeys can be completed within a reasonable fraction of the traveler's life time then I'd argue that all bets are off. To all intents and purposes, that civilization has access to an entire galaxy worth of raw materials and energy, plus the technological wherewithal to harness and exploit very substantial quantities of energy at a time. At that point, the decision whether or not to bother with planets almost becomes an aesthetic choice or a moral choice with access to raw materials becoming a secondary factor.

With all that said, I like @daniel l.'s jewel analogy.  A civilization that leaves inhabitable worlds as natural parks is a civilization that I'd want to be part of.

Without FTL, we're trapped in the Sol system and here I think @Mitchz95 is right. Consider that the asteroid belt is estimated to only contain about 0.04 Moons worth of material. The Kuiper belt is estimated to contain about 200 times as much. That's still a lot but not so much on the scale of the whole solar system. The Oort Cloud is hypothesized to contain still more material but at a vast distance. (Put into context - Pioneers 10 and 11 haven't reached it yet.) The trade-offs between quantity of material and time/energy requirements to exploit that material become a lot more restrictive than they would be for our FTL capable super-civilization and, whilst I'd like to believe in a predominantly asteroid inhabiting civilization, I don't think planets could or would be ignored.

 

[kerbiloid]

The Earth is much more versatile resource bank than asteroids, moons and Mars due to its hydrosphere, biosphere and long-lasting geological activity in the Solar habitable zone.
Because liquid water solves minerals and moves them to the surface, making high-concentrated hydrothermal deposites,
and because different junk sinks and concentrates on the ocean floor to be later accessed as sedimental deposites.

And compared to delta-V required for the asteroid belt and the outer planets, delta-V of lifting looks metal constructions from the Earth surface to LEU not so great price.
So, really advance civilization unlikely will prefer asteroids as sources of resources, compared to a big watered planet in a warm zone.
As an auxillliary source - of course, some of them, with an occasional rare earth elements spot.

Imho, very probably an advance civilization will rework numerous asteroids to vaults/habitats, but a really advanced civilization unlikely will need celestial bodies to live.
They will need habitable zone-sized trailer parks for their townships, their homeland planet as a sanctuary, and sometimes - warm, watered planets in a habitable zone (like ours) as a miner's paradise.

Though they for sure will need not so many resources due to ~100% recycling of their wastes.
And unlikely their civilization will have so numerous individual personatilities to colonize every piece of rock.

[Bill Phil]

5 hours ago, KSK said:

How advanced a civilization are we talking about here?

If we're assuming access to some kind of FTL capability such that interstellar journeys can be completed within a reasonable fraction of the traveler's life time then I'd argue that all bets are off. To all intents and purposes, that civilization has access to an entire galaxy worth of raw materials and energy, plus the technological wherewithal to harness and exploit very substantial quantities of energy at a time. At that point, the decision whether or not to bother with planets almost becomes an aesthetic choice or a moral choice with access to raw materials becoming a secondary factor.

With all that said, I like @daniel l.'s jewel analogy.  A civilization that leaves inhabitable worlds as natural parks is a civilization that I'd want to be part of.

Without FTL, we're trapped in the Sol system and here I think @Mitchz95 is right. Consider that the asteroid belt is estimated to only contain about 0.04 Moons worth of material. The Kuiper belt is estimated to contain about 200 times as much. That's still a lot but not so much on the scale of the whole solar system. The Oort Cloud is hypothesized to contain still more material but at a vast distance. (Put into context - Pioneers 10 and 11 haven't reached it yet.) The trade-offs between quantity of material and time/energy requirements to exploit that material become a lot more restrictive than they would be for our FTL capable super-civilization and, whilst I'd like to believe in a predominantly asteroid inhabiting civilization, I don't think planets could or would be ignored.

 

Ah, but the moon systems of the giants and their Trojan asteroids provide even more material for exploitation, without mining planets. Although some of the moons are pretty close.

And, for a settlement that is proposed, most of the mass (more than 90%) is shielding. That can be just about anything. Heck, hydrogen from a giant planet might suffice, if you can recover the energy costs by fusing some of the hydrogen you acquire.

[regex]

5 hours ago, KSK said:

Without FTL, we're trapped in the Sol system

No, we just need to tackle the problem in a different way.

As far as asteroid habitats I don't see hollowing one out to be the way to go. What seems more likely is using the valuable constituents to construct a frame (among other things) and then filling it in with all the detritus and a means of binding it. In that way you use it to the fullest. You might even have to go looking for those asteroids with a higher amount of relatively useless detritus to build habs from because I imagine there's a lot of useful material to begin with.

[mikegarrison]

Let's go back to the original post for a second, please. What data can you cite to back up the statement that all solar systems have asteroids?

[magnemoe]

1 hour ago, mikegarrison said:

Let's go back to the original post for a second, please. What data can you cite to back up the statement that all solar systems have asteroids?

We do not at least not as many as our solar system, on the other hand it will be plenty farther out. Gas giants has lots of moons. 

Main issue is why go to another star to live in its asteroid belt. it would take an long time until our own is mined dry, think dyson swarm, and they are very uncommon as we would detect them in an far distance. 
Only reason to go for asteroids in another star system would be if chased out. 

Planets with life would be very interesting for research in the first place so an permanent base makes sense, yes its likely to also contain plenty of space infrastructure. 

You can also have two planets with life, had Mars been larger as in half earth mass or more it would likely had life. This would been an major boom to space activity.

[kerbiloid]

2 hours ago, mikegarrison said:

What data can you cite to back up the statement that all solar systems have asteroids?

If it has rocky planets, it must have asteroids. Just because of statistical distribution.

[mikegarrison]

18 minutes ago, kerbiloid said:

If it has rocky planets, it must have asteroids. Just because of statistical distribution.

Well yes, I think this is likely. But my point was that until VERY recently we had no direct evidence that any other stars even had planets. We have certainly never actually detected asteroids in any other solar system. So yes, we assume that they will exist and we have good reasons for that, but we don't know that they do.

[kerbiloid]

12 minutes ago, mikegarrison said:

We have certainly never actually detected asteroids in any other solar system.

Looks like they've found something.

https://www.nasa.gov/mission_pages/spitzer/news/spitzervega20130108.html

https://exoplanets.nasa.gov/resources/30/

https://www.space.com/986-asteroids-sun-star.html