I've found a water world that is a candidate for terraforming and that world has fairly large ring. What I came to think about is that I really wouldn't want to live, even though it would be spectacular, in a world where there are millions of rather large rocks that may fall down with catastrophic result. But perhaps these rings are really stable and the rocks are actually locked in orbit with no possibility to enter the atmosphere with out some force from outside the ring. It is so or do we see rocks falling out and into the atmosphere of let say Saturn or Jupiter (it has a faint ring)?
Are the rocks in a ring stable?
- Thread starter Salkinius
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by definition every object in orbit is always falling all the time, so no, they'd probably be in a stable orbit since they're also as old as the planet.
a stable orbit is where an object is falling fast enough that it falls all the way around the planet without a ballistic trajectory (IE hitting the floor) - think about it this way, if you launch a rocket straight up, it comes back down to the ground. if you launch it at an angle, it lands further away. for it to be in orbit, it would have to be going fast enough that it's trajectory would miss the ground entirely, and bring it back to another circle. (hence the falling, it falls so far it misses the floor)
it's likely that some of the inner rocks will end up in a decaying orbit, though. but these may burn up in any atmosphere. (if the ring is large diameter and inner radius then it won't have any of these, if it's very close it might.)
a stable orbit is where an object is falling fast enough that it falls all the way around the planet without a ballistic trajectory (IE hitting the floor) - think about it this way, if you launch a rocket straight up, it comes back down to the ground. if you launch it at an angle, it lands further away. for it to be in orbit, it would have to be going fast enough that it's trajectory would miss the ground entirely, and bring it back to another circle. (hence the falling, it falls so far it misses the floor)
it's likely that some of the inner rocks will end up in a decaying orbit, though. but these may burn up in any atmosphere. (if the ring is large diameter and inner radius then it won't have any of these, if it's very close it might.)
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The rings are only a fraction of the rocks in a solar system. There's hundreds of thousands of them careening all over the place. If you look up "Amor Asteroid", you'll see a belt of them that mostly traverse the orbit of Mars. Deimos & Phobos are likely amor asteroids that got caught by Mars. Check out the 2009 Jupiter impact event:
http://en.wikipedia.org/wiki/2009_Jupiter_impact_event
This ought to answer your question about the stability of rings.
Generally, though, measured over human lifetimes, space rocks are very stable. Judged by planetary lifetimes, well, look at the moon and decide why it is cratered so. Likely something sooner or later will come into impact with the rings. Rings don't just magically appear: they are themselves the result of a planetary impact. So if one thing can come along to make rings, certainly another could travel the same path.
After all that, you could also measure stability in stellar lifetimes instead of planetary ones. Stars inhale and exhale sort of like anything else that lives and breathes. If they cannot breathe anymore, they fall apart and die, a truly simplistic explination for a complex phenomenon. Main sequence suns like Sol will expand and eat a few planets before they cool off.
Believe it or not, there exist plans to save the Earth from stellar expansion, which should occur in roughly 4-5 billion years. The big minds are considering strapping engines to the Moon and using it as a gradual slingshot to break Earth out of solar orbit. Several thousand passes ought to be gentle enough to break the Earth free without destroying everything. But there are also plans to mount engines on the continents and go at it that way. Tough luck, Australia.
We have to act fast, though. Just because the Earth may be swallowed by the Sun in 4 billion years doesn't mean it won't get sweltering hot, first. Earth will probably endure Venus or Mercury like surface temperatures in under a billion years anyways. Even Canada. Scotland might be nice, though: no more crazy horizontal rain all the time.
EDIT: Thinking more on the stability of rings, it's the people that are the problem. Consider that in ED there is more than enough space for everyone, yet everyone is constantly at war. So you set up Damocles City on ringed planet Twelvefield, sooner or later some military genius will hit upon the idea of strapping cheap engines onto the rocks and bombarding Damocles with stones from space. Each rock would hit with many hundreds of times the force of a nuclear blast. Maybe in the far future there's a defense for that, but even that far ahead, Sir Isaac Newton will still be relevant.
http://en.wikipedia.org/wiki/2009_Jupiter_impact_event
This ought to answer your question about the stability of rings.
Generally, though, measured over human lifetimes, space rocks are very stable. Judged by planetary lifetimes, well, look at the moon and decide why it is cratered so. Likely something sooner or later will come into impact with the rings. Rings don't just magically appear: they are themselves the result of a planetary impact. So if one thing can come along to make rings, certainly another could travel the same path.
After all that, you could also measure stability in stellar lifetimes instead of planetary ones. Stars inhale and exhale sort of like anything else that lives and breathes. If they cannot breathe anymore, they fall apart and die, a truly simplistic explination for a complex phenomenon. Main sequence suns like Sol will expand and eat a few planets before they cool off.
Believe it or not, there exist plans to save the Earth from stellar expansion, which should occur in roughly 4-5 billion years. The big minds are considering strapping engines to the Moon and using it as a gradual slingshot to break Earth out of solar orbit. Several thousand passes ought to be gentle enough to break the Earth free without destroying everything. But there are also plans to mount engines on the continents and go at it that way. Tough luck, Australia.
We have to act fast, though. Just because the Earth may be swallowed by the Sun in 4 billion years doesn't mean it won't get sweltering hot, first. Earth will probably endure Venus or Mercury like surface temperatures in under a billion years anyways. Even Canada. Scotland might be nice, though: no more crazy horizontal rain all the time.
EDIT: Thinking more on the stability of rings, it's the people that are the problem. Consider that in ED there is more than enough space for everyone, yet everyone is constantly at war. So you set up Damocles City on ringed planet Twelvefield, sooner or later some military genius will hit upon the idea of strapping cheap engines onto the rocks and bombarding Damocles with stones from space. Each rock would hit with many hundreds of times the force of a nuclear blast. Maybe in the far future there's a defense for that, but even that far ahead, Sir Isaac Newton will still be relevant.
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Depends on how large the rocks are too. You might just get spectacular meteors once in a while.
Also if one rock is moving ever so slightly faster or slower than another one they may collide and push each other out of stable orbit and hit the planet.
Even if they just pass real close their individual gravity might be enough to give an unstable orbit.
Even if they just pass real close their individual gravity might be enough to give an unstable orbit.
This reminded me of flight school, Hitchhiker's Guide style.
I was watching Wonder of the Solar System and Mr Cox was saying how the ice in Saturns rings is constantly in flux, each piece constantly hitting other pieces and chipping bits off. One of Saturns rings is made almost entirely from ice which is being blown off a moon by eruptions of water from under the surface. I think this is right anyway.
I think i'm also correct in saying they had to alter the path of the Voyager because they thought there was a gap between the rings and the planet, but the gap turned out to be really fine dust that's almost invisible at the distances we can see it from. I would assume at least some of this would be constantly falling to the planet.
I think i'm also correct in saying they had to alter the path of the Voyager because they thought there was a gap between the rings and the planet, but the gap turned out to be really fine dust that's almost invisible at the distances we can see it from. I would assume at least some of this would be constantly falling to the planet.
some particulate and smaller chunks probably, they'd burn up in an ELW atmosphere. i think the majority of it is locked into orbit through it's angular velocity rather than it's relative velocity (IE you can get knocked about but not lose orbital velocity see the film gravity for easy examples of this)
So I gather that even though the rocks are stable in orbital ring the likelihood of a meteor strike on the planet is far greater than it is on a planet with no ring? Right? So my question is still valid. Would a world with a ring in game really be up for terraforming? Would there even be an earth like planet with these conditions?
If a terraformable planet has sizable rocks in its rings, then the chances of an impact are naturally higher. Even a near-miss from an asteroid could throw parts of the ring out of its orbit and send them in assorted directions, including down to the planet below. Of course, in the year 3300, one could just send out a ship or two to demolish incoming asteroids or cause them to change orbit away from settled planets.
Tempus-Fugit
Banned
The examples of rings we have in out solar system are not made of giant rocks. They are made mostly of small ice crystals that wouldn't even get close to making it through even the thinnest atmospheres.