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I'm just a guy who is interested in all topics around space, so forgive me if it is a dumb question.

I have read some things about asteroid mining in the past and I think it's a really interesting topic, as it opens up a lot of possibilities.

But one thing came to my mind. Humans tend to pushing things a little too far sometimes when we want to reach a goal. So, imagine, we are getting really good at off-earth mining at a larger scale and in a larger timespan, we continue to mine thousands and thousands of asteroids. Wouldn't that affect the gravitational balance of our star system at some point, or is the gravitational influence of an asteroid belt negligible? I am talking about extreme examples, like removing nearly the whole asteroid belt beyond Mars. Also, what would happen to all the stuff we don't need from an asteroid?

I'm sure I'm not the first one who thinks of something like this, but I found nothing about this particular topic.

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  • $\begingroup$ This question would probably be better asked on the space exploration stackexchange site. $\endgroup$
    – David Hammen
    Jun 9, 2016 at 10:46
  • $\begingroup$ I think the true potential of asteroid mining isn't so much overloading the planet with everything we can get our hands on because planets-worth of useful materials are drifting around just past Mars, but instead these materials are far more likely to just be used for the creation of massive structures that are built in space and stay in space. The solar system never loses mass; the mass just gets moved around a bit. The only way this might cause gravitational disruption to things is if we somehow clumped the entire asteroid belt together and made an artificial planet out of it. $\endgroup$
    – Logan
    Jun 9, 2016 at 13:06
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    $\begingroup$ @DavidHammen Your answer may be geared toward Space Exploration, but even though the premise of the question is asteroid mining it is perfectly on topic here since it is merely asking "If the asteroid belt were depleted, would it affect the gravitational balance of the solar system?" This is an astronomical question. $\endgroup$
    – called2voyage ♦
    Jun 9, 2016 at 15:55

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Something to remember is that the total mass of asteroids in the asteroid belt is tiny compared to the masses of the planets. Ceres, the largest body in the asteroid belt by a wide margin, is only 0.00015 times the mass of Earth, Ceres itself accounts for about a third the belt's mass:

Asteroid belt facts from ScienceDaily

I haven't been able to find any papers or articles that suggest the residents of the asteroid belt have any measurable perturbation on the orbits of Jupiter and Mars (the other way around is a different story!). If the asteroids that spend most of their time near Mars and Jupiter were to disappear, I doubt there would be any observable effect on the orbits of the planets.

Consider that comets and asteroids commonly pass close to Earth and the Moon and their influence on Earth's orbit is negligible.

As for what we would do with what we don't need from an asteroid, there are a few options I could think of based on the size of the target. With smaller asteroids, if there is a risk that any changes to its orbit (such as an impact or accidental explosion) that would send it close to Earth, a complete controlled demolition of it might be warranted, or simply attach large chemical rockets to it and push it away. In the near-future, it is likely that even if we do start mining asteroids, provided we haven't dangerously altered its orbit, they will simply be abandoned afterwards.

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  • $\begingroup$ I think this answer is good. I really thought the total mass of all asteroids in the belt would be higher. Regarding the dust of the asteroid remains, today I read about a plan to bring the asteroids with some kind of vessel to earth instead of going there and mine them at their original position. In my scenario with this method, I think we would either get some rings of dust around our planet or we would try to steer them into the atmosphere (not really safe, isn't it?) $\endgroup$
    – Matthias Nicklisch
    Jun 10, 2016 at 9:16
  • $\begingroup$ Thank you! You're right, moving anything into orbit poses risks, and new planetary rings would make launching from the surface even more difficult. Regarding asteroid redirection or mining, I think any further questions on those would be better suited to SpaceExploration or WorldBuilding. $\endgroup$
    – user10106
    Jun 10, 2016 at 12:04
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So, imagine, we are getting really good at off-earth mining at a larger scale and in a larger timespan, we continue to mine thousands and thousands of asteroids.

First off, that is a problem for our children's children's children to solve. It is not our problem. The quantity of materials mined from space so far is a bit over 380 kilograms, the 382 kilograms returned from the Moon by the Apollo missions, the 300 grams of materials returned from the Moon by automated Soviet spacecraft, 7 particles of interstellar dust returned from comet Wild 2 by the Stardust spacecraft, and 1500 particles of dust returned from asteroid Itokawa by the Japanese Hayabusa spacecraft.

For the foreseeable future, there is very little stuff in asteroids that is worth anything on Earth. There is no point in mining commodity metals in space and bringing that material down to Earth. Doing so would be a money-losing proposition. Mining precious metals in vast quantities would turn those expensive precious metals into worthless commodity metals.

One thing that might be of value on Earth is helium 3, but that is so very, very rare that bringing it down to Earth will have zero effect on the Earth's mass. This of course depends on making fusion viable; that's been cited as being twenty years in the future since the 1960s. Current estimates are well beyond 20 years.

The foreseeable future (at most 50 years from now; anything beyond that is science fiction) of asteroid mining is using those materials mined in space in space. That opens the door to extracting substances that are extremely common on Earth. The same economics that dictates that mining precious metals in space doesn't make sense economically means that sending consumable up into space doesn't make much sense economically. For now, the most valuable substances to be mined in space are volatiles such as water and methane. This assumes a sizable space infrastructure that needs those substances.

Wouldn't that affect the gravitational balance of our star system at some point, or is the gravitational influence of an asteroid belt negligible?

The asteroid belt accounts for about a billionth (one part in 109) of the mass of the solar system. The gravitational influence of the asteroid belt is negligible.

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