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Setting A World In An Asteroid Belt

I'm interested in setting my story in an asteroid belt, with the belt basically being the outer space equivalent of an archipelago. First, I would want to know if it is even feasible to have an asteroid belt filled with habitable worlds, and I was also wondering what the effects of living in a such a low gravity environment would be on any living things in my story. Is there any way to keep a reasonable level of gravity on various asteroids without messing up the entire scenario? Also, what length would the day night cycle be on asteroids like these, as well as the year length? For the sake of this thread, lets just assume that all the main asteroids in the belt are around the size of Pluto, maybe a bit bigger.
 

ThinkerX

Myth Weaver
Depends on the tech level.

That said, given enough mass (density), the larger worlds might be able to retain a thin atmosphere.
 

Vaporo

Inkling
A dwarf planet/asteroid the size of Pluto would have very little gravity. Even if they were made entirely of something really dense like lead, they wouldn't have much gravity. To reach the kind of density required to make an object that size have more than maybe a tenth of a G, it would have to collapse into a neutron star. As you might imagine, this is not very hospitable to life as we know it.

Even if a pluto-sized planetoid had earth-like gravity, it still probably couldn't support a breathable atmosphere. The reason that the earth can support an atmosphere is that the average speed of particles in the air is lower than orbital velocity. Because of this, the any air that tries to fly off the earth just falls back down. Thus, an atmosphere. So almost any life would be confined to manmade biospheres. Any people living in a low or zero gravity environment would suffer from a number of health issues, primarily muscle loss and loss of bone density. These effects could be mitigated, though, with the clever use of centrifuges.

Year length could be almost anything, depending on the size of your parent star and how far away the planetoids are. The length of the day would be limited by the orbital velocity of your planetoids. i.e. A planet spinning at a speed near its orbital velocity would be distended into an egg shape, and a planet spinning faster than its orbital velocity would tear itself apart.

Also, depending on their number, gravity, and orbit, there may be a distinct threat that these planetoids could collide.
 
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jm.milks

Scribe
The most obvious effect of low gravity environments on living organisms is muscle growth. Within the first few generations during colonization, you're people /organisms would be skinny af. Like picture the skinniest person in sub Saharan Africa and then a bit skinnier.

That is, at least if there's no such thing as artificial gravity, which could be achieved in various ways (such as with circular structures rotating fast enough to match whatever level of gravity they need. Think of the gravitron at the fair if you've ever been on one).

In zero gravity, people will be taller, and though with a relatively miniscule muscle mass, would still retain the same sense of strength as they would on earth, again relatively.

The primary purpose of an asteroid colony would be for mining the various elements and resources found in asteroids, so 9/10 it would be a mining colony, though between the four major colony types (agricultural, productive, commercial, scientific), there could also be research colonies, depending on nearby anomalies or things you could place (maybe there are remnants of a decreased civilization across the system).

Day cycles wouldn't matter, and year cycles would depend on how far away from the star (and how large). In such a situation, they would likely adopt increments based on mathematical formulas (the way a second is measured by a set number of vibrations in a certain particle).

If you have any more questions I'll be happy to help with what I know. Just message me if I didn't give what you were specifically looking for.

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Thanks for the replies! If pluto-sized is too small, then how big would the asteroids have to be to be habitable while still falling into an asteroid belt-ish formation? They don't have to be very close together, just close enough that someone would be able to travel between them in a reasonably short amount of time.
 
Also, an alternative for me would be to set it on a ring of moons around a planet. Would that make more sense? And once again, how large would the moons have to be to be habitable? For this situation, just assume the planet the moons are orbiting is Earth-sized.
 

jm.milks

Scribe
Pluto is a dwarf planet, and anything that large our larger would be subject to strikes every so often because of its gravity. (It would also clear out an area around it eventually from absorbing asteroids)

Another thing to keep in mind is that asteroid belts are much more spread out than people illustrate (they rarely ever collide because they're so far apart), but I could envision it only taking about an hour or two for anyone to commune between.

As for moons around a planet, if you want habitual worlds, (earthlike composition and can sustain biological life), you're likely limited to four moons that reside in the goldilocks zone.

The gas giant (it would have to be one) could sustain the electro magnetic field, so planets could be smaller (mars size?) and still retain its atmosphere and protection. Compasses would point towards the gas giant, alternatively to asteroid mining, settlements could harvest gases from the giant for fuel on floating platforms suspended by balloons (picture oil platforms in the ocean, but floating in a an everlasting hurricane).

There could be numerous moons, as well several ring systems around the same planet (rocky if in habitable zone, icy rings if father away). Rocky rings would function much like an asteroid belt, and everything I've said would apply (though a bit closer in most cases).

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teacup

Auror
"The Expanse" does this so it might be worth reading or watching that (it's a book series and a tv show now.) Or you could do both, since the books have the people born on the belt different to how they are in the show.

Pasted from "http://expanse.wikia.com/wiki/Belter" :
"Humans born to the Belt are taller and thinner than those on Earth and Mars because of the decreased gravity. "
"Due to the effects on the human body in low gravity, Belters have great difficulty in completing normal, healthy pregnancies. Abdominal and uterine muscles atrophy from underuse, rendering labor a very lengthy, painful, and dangerous process. When possible, Belter women will relocate to Ceres station where the spin gravity allows a more predictable pregnancy and delivery."


I think there's more to it than what's on that link, but I can't remember all of the things life on the belt affects. (This is referring to the books, not the show. I can't remember how the show did it.)


I think in both they have it so the people aren't living on the asteroid surfaces beneath the sky like you would a planet. I can't remember which, but the places the people live are either structures on the surface but under a dome or whatever, or they're structures inside the asteroids. They aren't naturally habitable so water and oxygen and whatever else is imported from elsewhere.
 

jm.milks

Scribe
"The Expanse" does this so it might be worth reading or watching that (it's a book series and a tv show now.) Or you could do both, since the books have the people born on the belt different to how they are in the show.
...

That sounds like an awesome series.

You had a lot of good points I forgot, and reminded me of another thing. Astronauts never have the urge to pee (No gravity to give the sensation), so they need to do it regularly and with help sometimes or their bladders will burst

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teacup

Auror
You had a lot of good points I forgot, and reminded me of another thing. Astronauts never have the urge to pee (No gravity to give the sensation), so they need to do it regularly and with help sometimes or their bladders will burst
Thanks, as did you:)
Woah that's cool, I didn't know that.


I like the series a lot so far, just started book 4. I recommend both the show and the books.
 

jm.milks

Scribe
Thanks, as did you:)
Woah that's cool, I didn't know that.


I like the series a lot so far, just started book 4. I recommend both the show and the books.
I've seen ads for it, but been hoping for it to wind up on Netflix or Hulu. I had no idea it was a book series til today. I'll certainly check those out first.

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teacup

Auror
I've seen ads for it, but been hoping for it to wind up on Netflix or Hulu. I had no idea it was a book series til today. I'll certainly check those out first.
It took a while for me to get into it, but once I did I loved it, so if you feel the same at first I'd say to just keep at it. Hope you enjoy them :)
 
I think it would make the most sense to have the setting be on 5 or 6 habitable moons orbiting around gas giant, with mostly earth-like conditions and gravity, with many other smaller moons also orbiting the planet. Are there any other problems with this or does this work out?
 

jm.milks

Scribe
The only issue with that is the moons would have to orbit each other so closely that they would be effected by each other's gravity. That or be spread out in such a way that at least one or two would spend much of their orbital period outside of the habitable zone, either too close, too far, or both to the star.

But honestly, this is a very little known, and science can be stretched a bit in a fantasy setting.

Hell, if a civilization is advanced enough, they could use synthetic fusion to heat any object too far from the sun.

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Vaporo

Inkling
The only issue with that is the moons would have to orbit each other so closely that they would be effected by each other's gravity. That or be spread out in such a way that at least one or two would spend much of their orbital period outside of the habitable zone, either too close, too far, or both to the star.

The moons could also be in orbital resonance with each other, like the moons of Jupiter:
Galilean_moon_Laplace_resonance_animation_2.gif
 

Penpilot

Staff
Article Team
Without the intervention of technology or magic, asteroids are not massive enough to keep an atmosphere dense enough for life. They also don't have magnetic fields which aids in protecting the planet from radiation.

From this wiki entry. Planetary habitability - Wikipedia, the free encyclopedia it says the following.

it would be fair to infer that the lower mass limit for habitability lies somewhere between that of Mars and that of Earth or Venus: 0.3 Earth masses has been offered as a rough dividing line for habitable planets.[42] However, a 2008 study by the Harvard-Smithsonian Center for Astrophysics suggests that the dividing line may be higher. Earth may in fact lie on the lower boundary of habitability: if it were any smaller, plate tectonics would be impossible. Venus, which has 85% of Earth's mass, shows no signs of tectonic activity. Conversely, "super-Earths", terrestrial planets with higher masses than Earth, would have higher levels of plate tectonics and thus be firmly placed in the habitable range
 

Trick

Auror
If you're going for a fantasy/sci-fi mix, why not have the asteroids contain some sort of practically unending fuel/energy source that allows for everything needed to make them habitable? It could power an entire mechanized ecosystem.
 
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