So I found out that it would under certain circumstances be economic to harvest Asteroids.

Given the following:

  • Technological level is nearly similar to todays Earth.
  • There are transportships which can carry material through any place of the solarsystem.
  • There is a facility in the Main Asteroid Belt which can process said asteroids.

My question now: Is installing a facility inside an asteroid belt and navigating around in said asteroid belt safe?

What to do with the waste? Get a ship and throw it in the sun?

How much would accidents increase the danger in the area (Kessler Syndrome)?

I think that slow moving asteroids can easily be evaded or catched and redirected/processed, but how high is the risk of fast moving asteroids? Or how likely would it be to get into a high-density area where are simply too many objects for any actions?

I thought about placing the facility in an higher or lower orbit than the belt, but that would result in mining ships (which would collect asteroid-material for processing) would either have to catch-up with the station, fall back to it or make a nearly full round around the sun to get to the station again. This seems impractical.

  • $\begingroup$ Larethian: You've mentioned playing KSP, have you tried out Space Engineers? Like KSP, it is also available on Steam, and complements KSP almost perfectly. KSP teaches orbital mechanics and the process of creating systems to get around, Space Engineers deals with space survivability and material resource management. It features meteor showers/storms, floating debris, and refining facilities inside of asteroids- all features of your question. Both games are sandbox-type simulations and both are highly addictive! $\endgroup$
    – Steve
    Commented Dec 10, 2014 at 22:41
  • $\begingroup$ Yes, there's no safer occupation than mining. Especially when you're perched on a snowball whipping through space at a million miles an hour. WhoooooOoooooooooOoooo Safe! $\endgroup$
    – Samuel
    Commented Dec 10, 2014 at 23:58
  • 1
    $\begingroup$ @Steve I have and play both. I know that KSP simulates the orbital mechanics quite well, but I hvae no idea about real asteroids. SEs Asteroids are pretty static, and I wasn't sure about the Meteors realism (come on, flaming balls in space?) $\endgroup$
    – JFBM
    Commented Dec 11, 2014 at 0:31
  • 1
    $\begingroup$ Odds of major asteroid/Earth collisions can be greater due to size of Earth. In the asteroid belt itself, objects tend to move at about the same (orbital) speeds, so relative velocity is usually near zero. $\endgroup$ Commented Dec 11, 2014 at 1:30
  • 1
    $\begingroup$ One additional element to this question that I am interested by- is there a risk of bringing enough stuff to earth/earth orbit that we start causing problems due to changes in mass or gravitational effects? $\endgroup$
    – glenatron
    Commented Dec 11, 2014 at 10:16

7 Answers 7


Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist's, but that's just peanuts to space.

--Douglas Adams, The Hitchhiker's Guide to the Galaxy

The distances involved are literally astronomical.

A "high-density area" in an asteroid belt is still going to be better than 99% empty space. Get the movie images of ships being immediately pelted by thousands of rocks the moment they cross the "boundary" into an asteroid field out of your head -- that's complete fiction.

Case in point: We've sent numerous probes through the asteroid belt to regions beyond (e.g Voyager I, which has "left the solar system" a couple dozen times...), and did absolutely nothing to evade asteroids or protect against them while passing through the belt.

That said, you put a big, "stationary" industrial processing center anywhere in space, and you do run the risk of asteroid impacts. So figuring out ways to protect your center is still a good idea. Most asteroids are essentially pebbles, really, so just using a tough outer shell will cover you against greater than 99% of the impacts you'll encounter during the lifetime of the facility. [Not to imply that dust/pebbles are harmless, mind you, just that, relative to the "big 'uns", they're easier to defend against by just using a really tough outer shell; in any case, it's barely a marginally-increased threat in the asteroid belt versus anywhere else in space.] The really big rocks are so few and so far between (literally astronomical distances between them) that your odds of ever being struck by one really aren't worth considering. If you really want to be paranoid, though, you could always find a big asteroid and mine into it, then build your processing center inside.

And if in the off chance a big asteroid is heading straight toward you, you'll generally have plenty of time to put together a crack team of aging ex-astronauts to fly out to the thing, drill a couple of holes, and set the nukes. Or just get out of the way. Or, if in the unlikely event neither is possible, just evacuate the facility, consider it a loss (if it actually does get hit) due to natural disaster, collect the insurance payout (you did buy the asteroid rider on your insurance policy, right?), and then rebuild (just like terrestrial industrial facilities have to be rebuilt after hurricanes, tornadoes, earthquakes...).

Really, working in the asteroid belt is no more dangerous than being in any other part of space. Maybe a 0.000000000001% increase in your odds of getting hit by a big space rock. Given all of our history of space flight, going to space is far safer than crab fishing in the Bering Sea, and working in the asteroid belt is very unlikely to dramatically alter that fact.

And ultimately, no matter where you put it, mining ships will have to catch up or fall back to your facility. That's just how space travel works (here again science fiction movies have lied to you). Everything's in its own orbit, and rendezvousing always requires moving to higher and/or lower orbits. The only exception would be if you put your processing facility directly on or in orbit of the rock you're actively mining, but at that point it might make more sense to just incorporate the processing facilities directly into the mining ships themselves so they can always take them with them!

And the waste? Just chuck it into space. See again: Space is very big. Kessler syndrome is exceedingly unlikely to cause you any problems out there -- it's really only a (potential) issue in low-Earth orbit, and that's only because we're talking about a very small amount of space. If you're really worried about it, pulverize it into dust first. You're probably doing about the same thing to extract the ores you're actually after anyway.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ Commented Dec 11, 2014 at 19:01
  • $\begingroup$ You mentioned that pebbles weren't worth worrying about. Except that a speck of dust nearly put a hole through the Space Shuttles wind screen. Things in space move incredibly fast - making even small objects very dangerous. This makes working on the inside of an asteroid very attractive. $\endgroup$
    – Jim2B
    Commented Oct 6, 2015 at 19:02
  • $\begingroup$ @Jim2B Edited to reflect what I meant about dust/pebbles being less of a worry (versus not a worry at all). You're absolutely right that even really small things, given enough speed, can be very dangerous, and hopefully this clears it up that I was referring not to absolute danger, but to relative danger: A very fast piece of dust might nearly punch a hole in a window, but an equally-fast rock the size of Texas will utterly pulverize the shuttle without even slowing! It's also worth noting that that speck nearly punched a hole, proving the point that a tough shell can be enough protection. $\endgroup$
    – Kromey
    Commented Oct 6, 2015 at 19:28
  • $\begingroup$ "And the waste? Just chuck it into space." Don't see why. It will make excellent protection against the rare collisions. The longer you operate and accumulate buffer material, the safer (and more reliable) the refinery is. It will also be cheaper than chucking it, so the refinery will be more profitable. $\endgroup$ Commented Oct 6, 2015 at 23:27
  • $\begingroup$ @WhatRoughBeast Chucking it is more expensive than refining it into a usable building material and then affixing it to your structure? How?? $\endgroup$
    – Kromey
    Commented Oct 6, 2015 at 23:37

Safety is a matter of perspective. Simply living in space is dangerous. We take measures to reduce the risks, but they are still there.

Now while the majority of the asteroids in the solar system are in the asteroid belt there are still plenty moving around in other areas. Finding these more singular ones might be a much 'safer' bet, at least to start with, partly because they could be much closer to an earth orbit, but I'm not sure if that is as important. A single largish asteroid could take several years to mine down to nothing. I also wouldn't worry much about the waste, likely it could be used for something and if not if it is kept together is could be just a small asteroid floating around, waiting for someone to need what is in it.

Now the asteroid belt, while it covers a large area and has a lot of stuff in it, apparently has less mass in total than our moon.

About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, and Hygiea. Vesta, Pallas, and Hygiea have mean diameters of more than 400 km, whereas Ceres, the asteroid belt's only dwarf planet, is about 950 km in diameter.

So our asteroid belt is no where near as crowed as we see on the star wars flight scenes.


Safety isn't a particular issue, but with anything close to current technology, "the Asteroid Belt" is a vast place to be commuting around-- it encircles the sun in an orbit wider than the Earth's, and traveling from one asteroid to another would in general be a long and expensive voyage. You'd probably focus on just one juicy asteroid, in which case it would make a lot of sense to live inside it (since you're excavating anyway); then you have good protection from both radiation and debris.

Of course, if the destination for the mined resources is Earth, there is a lot to be said for bringing the mountain to Mohammed as Rob Kinyon says-- either parking it in orbit or just (carefully) landing it in the ocean. No commercial enterprise is going to pay $6 million a year for someone to work a jackhammer if they don't have to, after all.

However, a major market for asteroid-mined materials would be other space construction projects, where anything shipped from Earth is hugely expensive because of launch costs. The economics of that market would favor extracting and refining minerals at the source, and launching them on a slow but super-efficient trajectory to their destination. So, you'd continually fire aluminum ingots out of a cannon on Ceres, expecting to sell them 20 years later when they show up orbiting Ganymede. It raises a lot of interesting narrative possibilities (e.g. people hijacking the material en route)...


Today, mining is one of the most dangerous occupations a person can engage in. According to the CDC, there were 19.8 workplace fatalities per 100,000 miners in the US in 2010. There are also other risks that are harder to measure, such as increased cancer risk due to exposure to mining dust. In the developing world, the fatality rate is higher still.

One occupation that is more dangerous is fishing, due in large part to the fact that out at sea, there is limited access to rescue services or medical treatment. This would also be the case for asteroid mining, increasing the risk.

Another occupation that is more dangerous is space exploration, with roughly 7.5% of all astronauts having died in accidents. Since asteroid miners would also be astronauts, this would also increase their risk. Astronauts are also exposed to high levels of cosmic radiation, which is expected to increase their cancer risk, but there is insufficient data to quantify this risk.

So even leaving aside the risk of asteroid impacts (which as Kromey has explained, is not as serious a problem as you might imagine), asteroid mining would be one of the most dangerous occupations around.


Asteroid mining is entirely possible - you just have to be very patient for things going back and forth over astronomical distances under budgetary restraints (not spending a lot for faster movement).

Moving a large processing facility out to the asteroid belt and then from asteroid to asteroid seems excessive as moving the asteroid to a refining facility seems more plausible, especially considering the easier task of exploiting near-Earth objects as well. The 'asteroid field' is not a thick chaotic mass of constant collisions and dodging rocks, but just some objects which happen to have the same orbit (with big spaces in-between). There is a question about this over on the physics board which might give you a better idea about the scales involved.

The cost of moving people out to the asteroid belt, keeping them in habitat there, and returning them in a reasonable amount of time would be exceedingly ridiculous. The radiation exposure during the transit to and from the site alone would be worrisome. If there is a need for human interaction, instead of purely automated processes (with some telepresence controls, though the time delay might present difficulties there), moving the asteroid back to a processing facility in Earth orbit would be a better solution.

Collisions are not an issue - I suppose making a mistake on trying to land on a tumbling object might be a concern, but impact with another is unlikely as they likely too far apart and their relative velocities would almost certainly be negligible. Comets might be a collision risk, as they would not be in the same orbit, but that risk would be the same (negligible) no matter where you are.

As far as 'waste' goes, there is no such thing - if it isn't an economically valuable material, it counts as either shielding or reaction mass.


Why aren't you refining as you mine? Why spend the fuel to transport material with no economic value? Why have people involved?

In Mining the Sky, Dr. John S. Lewis talks about using high pressure and high temperature carbon monoxide to vaporize and then deposit metals out of ground up ore. Different temperature and pressure combinations will vaporize different metals. So the same refinery can reprocess the dust multiple times to get different metals. Those metals would likely be chemically pure (unless two metals have similar temperature/pressure combinations). Why transport kilograms of rock to get grams of metal when you can just send the metal?

This process can be completely automated. Dr. Lewis' plan calls for the metals to be stockpiled for later retrieval but you can add some kind of launcher.

The waste dust is just deposited on the surface of the asteroid.


The cheapest and easiest thing would be to move the asteroid into L4 (next to the asteroids already there). It would take a few years after pushing it, but it would be captured by L4. Then, you handle the smelting there, then launch the finished products back to earth along the orbit. Don't need humans - teleprescence robots would be enough with a delay of 15min or so.

Remember - one 5km diameter asteroid has more useful material in it than all mining on earth in a decade.


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