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Most planetary rings are rich in water in the form of ice, especially now we are running low on freshwater reserves on Earth. Imagine someone discovered a huge chunk of meteorite consisting of a whopping 100 million carats and decided to auction it and then use the funds to mine the Saturn's planetary ring by hook or by crook, hellbent, relentless...

Set in the immediate future everybody raced to space once again. What would be a good non-political reason that can stop all kinds of mining of the planetary rings just within the solar system? We have volunteers, cash, Alibaba... so why not?

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    $\begingroup$ We are not running low on freshwater on Earth. There is plenty of it in Antartica, and it is about a million times cheaper to bring it from the South Pole than from outer space. Not to mention that with current commercially available technology desalinated sea water costs about one dollar per cubic meter (0.1 cents per liter). $\endgroup$ – AlexP Dec 30 '19 at 0:26
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    $\begingroup$ Penguins live on the coast. There are no penguins at the South Pole. (Antarctica is a very big place.) $\endgroup$ – AlexP Dec 30 '19 at 0:55
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    $\begingroup$ There is plenty of fresh water on Earth, even leaving Antarctica (and Greenland) untouched. The "problem" (or more accurately, fact of nature) is that it's unevenly distributed, and humans insist on overpopulating areas that have little. WRT the 100 million carats, I presume of diamond, production already has to be restricted in order to keep the price artificially high. $\endgroup$ – jamesqf Dec 30 '19 at 5:35
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    $\begingroup$ A diamond is only as valuable as the price paid by the buyer. Diamonds are basically valueless. I can buy solitaire scrap diamonds for 10 bucks a handful that once were in jewelry. $\endgroup$ – Rhodie Dec 30 '19 at 12:55
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    $\begingroup$ Does this answer your question? What motivation would people have for mining planetary rings? $\endgroup$ – Zxyrra Mar 2 at 2:57
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Two reasons

  1. Cost - it's not going to be cheaper to mine water in space. There's a massive energy cost to get something into space against Earth's gravity well, and if you're going to mine something like water, there are cheaper ways of getting it - like purifying salt water. Especially because asteroids only come in one size - bulk. If you've got need for all that iron - great! But if you don't, then it's just cheaper to mine the stuff where you don't need to fight gravity.

  2. Time - it takes a while to get asteroids from the rings of Saturn to Earth. Cheaper if you decide to spend more money on more fuel, but even still you could be looking at a turnaround time of decades, maybe even longer. And there's no guarantee that it's safe - accidents happen, which means even if you're promised five times your initial investment, that's going to take decades until you see the money and it's going to be a risk. Compare that to, say, a CD, and you'll see that people may want to make safe investments.

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    $\begingroup$ And might I add, the asteroid belt between Jupiter and Mars is closer to Earth than either of those, and has more resources of all kinds than planetary rings. $\endgroup$ – Failus Maximus Dec 30 '19 at 0:35
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    $\begingroup$ Whatever you mine now also needs to escape Saturn's gravity well to get back to Earth. Something that mining the asteroid belt won't have to deal with, if you are insistent on doing some space mining. $\endgroup$ – Ellesedil Dec 30 '19 at 18:16
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    $\begingroup$ And even getting the mined stuff to Earth is not that cheap. You have to change its trajectory enough to put it on collision course with Earth, and then you have to somehow brake it so it does not end up just disintegrating in the atmosphere or even creating a potentially dangerous impact crater. $\endgroup$ – Jan Hudec Dec 30 '19 at 23:37
  • $\begingroup$ @Ellesedil the gravity well is not that bad, the worst part is near the surface but it quickly tapers off. Mining the outer rings wouldn't be that much of an issue - rings tend to extend just to the point where the debris is flying off anyway. $\endgroup$ – toolforger Jan 1 at 11:21
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The only reason we would mine the rings is to bring water to solar system parts without water. That would NOT be Earth. We might go there for Mars or the Moon or fueling space colonies, but not for Earth. Earth has an abundance of fresh water. And we have continuously improving tech for filtration and desalination. It isn’t worth the space trip.

Isaac Asimov once wrote a short story about just how absurd the amount of water Earth has compared to human usage of the water. The story is called The Martian Way. It does a great job giving examples of just how much water Earth has for us if we just move it around. You can read about it on Wikipedia... I’m sure the actual text is archived somewhere.

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Would it be easier to mine rings, or to mine the icy bodies that feed them? How about icy asteroids, comets, or craters on the moon?

Then there's the PR element. Which would be more likely to receive a huge public outcry against it: picking up ice from the dark side of the Moon and random asteroids nobody can see, or mining those rings that so many people find beautiful? Yes, the rings wrap around planets bigger than Earth, and it would therefore take a great deal of time and effort to put a dent into them, but it's somehow much easier to see a campaign to get ring-mining regulated in the name of "protecting the heritage of all mankind" or somesuch succeeding, compared to declaring a hidden crater with some ice to be an International Park.

Things change greatly if you have other things going on in space. As many have said, mining rings for water on Earth is a waste of money and effort, when you could just use desalination or other tricks to isolate not-so-fresh water closer to home. If you have space-mining operations or colonies already, ring-mining seems slightly less pointless, but at the same time, regulating ring-mining for PR reasons also seems more likely. Especially if someone already set up ice-miners on icy asteroids or moons.

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Because it is DANGEROUS.

Space travel is full of hazards, micrometeorites can wreck a ship.Like this

The asteroid belt is full of tiny stones milling about. Each one can make fatal impacts on the ship hull.

By God's sake, a flack of PAINT shattered the windshield on a mission!

Now the asteroid belt is full of amorphous bodies, with ice and frozen gasses that will be ejected once you extract them. Lose a couple of ships to horrific accidents and the cost the just not worth it.

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    $\begingroup$ What is the photo of? Needs caption. :-) $\endgroup$ – SRM Dec 30 '19 at 18:26
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    $\begingroup$ and credit...... $\endgroup$ – Lightness Races in Orbit Dec 30 '19 at 18:30
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    $\begingroup$ bcsatellite.net/blog/… contains an image this one was cropped from. Claims it was posted on reddit Feb '18, and describes the experiment. $\endgroup$ – Bit Chaser Dec 30 '19 at 20:00
  • $\begingroup$ To expand on this, Saturn's rings are about as dense as an Earth sandstorm, and moving at thousands of meters per second. If you approach them wrong, you'll experience a hypervelocity sandblasting. $\endgroup$ – Mark Dec 30 '19 at 23:50
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    $\begingroup$ In reality, the Asteroid Belt is /extremely/ sparse. You have to worry much more about small object impacts in LEO than you have to do in the actual Asteroid Belt. It's not much more dangerous than orbiting in regular interplanetary space, and the various spacecraft humanity has sent into and through the asteroid belt have had neither the need, nor the capability to avoid being impacted by any objects that weren't visible from Earth, and close approach to any such objects were part of the initial mission design. $\endgroup$ – notovny Dec 31 '19 at 14:33
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A dire prophecy predicting doom and destruction might work. Many people would not believe in the prophecy unless otherworldly beings appear, as predicted. That might create a powerful social force for ending the extraction of resources from the planetary rings.

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In general, bulk commodities like water, fuel, food, or most minerals are terrible candidates for space production (rings or elsewhere) or for any other kind of interplanetary commerce. I used to have the intuition that, once things are "in space", it's easy to move them from place to place since they are in a low gravity environment. So you could acquire water ice out by Saturn, then gently send it on a slow orbit to Earth, and use Earth's atmosphere to slow it down for a gentle landing.

But, in fact, it takes a pretty significant acceleration to get something out of Saturn's orbit and into an orbit that will reach the Earth. Once it reaches Earth, it will be going at Earth's escape velocity and will require a significant heat shield to survive reentry, and the heat shield would need to be launched back to Saturn. You end up using fuel that is a sizable fraction of the material you are trying to transport.

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