Asteroid mining for fun and profit

The complexities of mining asteroids for resources are daunting. Here is a proposal on how to simplify it. And maybe even make it profitable.

(Working on the) Asteroid, from Wikimedia Commons

The concept of mining asteroids for resources is well-established. At least theoretically. Not much asteroid mining has actually taken place but there is at least an extensive Wikipedia page about it.

Most asteroids are quite far away from Earth. This is not necessarily a problem. Everything in space is moving, orbiting around something. When traveling somewhere in space you are not primarily interested in the distance to your destination but in the change of velocity required to get to the same orbit as your destination. This change in velocity is called delta-v.

Objects in space might be separated by great distances but very low delta-v. Traveling between such objects will take very long time but require very little change in velocity meaning it requires very little energy. An example of this is an object orbiting the sun at the exact same velocity as Earth but on the opposite side of the sun. The distance between the Earth and this other object will be very large but since they both have the same orbiting velocity the delta-v requirement to go from one to the other is minimal.

The opposite is also possible, short distances and great delta-v. For example, the distance between Earth's surface and an Earth orbit is only a few hundred kilometers. But the delta-v required for this short hop is more than 9000 m/s, a significant velocity and the very reason for all those powerful rockets.

Asteroids usually fall into the long distance, low delta-v category. Especially the near-Earth asteroids have orbits that are quite similar to Earth's and thus require very low delta-v to reach. The near-Earth asteroids also have another interesting quality. Having orbits similar to Earth means that they sometimes collide with Earth, this is usually in the form of harmless meteorites, but sometimes during Earth's history it has been in the form of catastrophic impacts. The mere risk of these apocalyptic asteroid impacts has led to quite a lot of money being spent on discovering and risk assessing near-Earth asteroids. To date more than 30,000 have been identified.

A planetary smorgasbord

Asteroids are not much different from earth. They share the same origin as earth and contain about the same type of metals, minerals and molecules as earth. But since they are much smaller than earth their contents are generally easier to get to. You do not have to dig kilometer after kilometer into the ground to mine the asteroids. On most asteroids everything is close to the surface.

There are different kinds of asteroids, increasing chances that you will find the one suiting your needs. The three main types are M-type, S-type and C-type asteroids, standing for metal, stone and carbonaceous. These three types could be vaguely likened to earth's geological division into core (M-type), mantle (S-type) and crust (C-type). This is no coincidence since asteroids have gone through some of the same planet forming processes as the Earth and hence have some of the same characteristics.

Made in space

The most straight-forward way to make money from asteroids is to mine them and send the results back to earth. There are many valuable metals and minerals in the asteroids, but platinum is usually mentioned as the best candidate for extraction. Platinum is a rather dense metal useful in some electronics and in catalytic converters. It is also as expensive as gold but much more abundant than gold in the asteroids.

It is probable that other elements will be mined from the asteroids as well, if mining ever commences. The real problem with platinum extraction from the asteroids is not how to get to the platinum but rather how to get it back to Earth. Or at least how to get it back to Earth in a way that is still profitable. This is a major problem but there are entities that think they can solve it. The American company AstroForge is determined to do precisely this.

Made for space

Since getting things from space to Earth is such a hurdle, other prospective asteroid miners have had the revolutionary idea to not export to earth at all, instead focusing on the space market. Of course, there is not much of a market in space, but the one there is will pay handsomely for almost everything.

The big advantage with the space market is that the competition sits on Earth's surface and it costs a fortune to transport anything from Earth to space. Supplies for astronauts that would cost a pittance on Earth are exorbitantly expensive once they reach space. This is a market opportunity for someone who can produce things in space.

One thing that is easy to produce on asteroids is water. Both S-type and C-type asteroids contain significant amounts of water locked into their minerals. Astronauts of course need water. But water can also be easily electrolyzed into hydrogen and oxygen, which happens to be the two ingredients in rocket fuel. Someone who is going to, for example Mars, will need a lot of hydrogen and oxygen to power their spaceship. Lifting it all up from Earth will cost a small fortune. Why not pay a small fortune to have someone produce it in space instead?

This was the business plan behind the two most famous asteroid mining companies: Planetary Resources and Deep Space Industries. I have to write about them in the imperfect since both companies have folded, in 2018 and 2019 respectively. Apparently it is no cake walk producing water in space.

Space is hard

Both Planetary Resources and Deep Space Industries foundered for a lack of investment capital. This might be due to the impatient nature of modern capitalism. But it is also a testament to the peculiar investment conditions that bedevil asteroid mining. Asteroid mining takes time. Even if an asteroid mining mission was launched today it would still take years, probably more than a decade, before there was any water to sell to prospective space buyers. That is the problem with the great distances of space. They take time to defeat. And that sort of patience is hard to come by in the investment sector.

Especially when you consider the daunting challenges involved in asteroid mining. Launching things into space is routine these days (something I wrote about recently). Traveling to distant asteroids is not routine, but not unheard of either. Transporting an asteroid back to Earth is unheard of. It is not that complicated in theory, but since no one has done anything similar chances are it will take a couple of tries to get correct.

Even if you manage to get your asteroid and take it back to Earth orbit the worst problems are still to come. What do you do with an asteroid? Almost every technology developed for terrestrial mining is dependent on gravity or air pressure, neither of which is present in space. Not even a simple sieve will work in space. Most probably there are methods for extraction that will work even in zero gravity, zero atmosphere conditions. But finding them, and finding out that they work, will most probably take a lot of time and cost a lot of money.

This is part of what makes water production in space so attractive. In contrast to platinum extraction, which no one knows exactly how it will be done, water extraction is relatively simple: You just crush the asteroid rock and heat it, water will be released as water vapor and can be collected and sold.

A bright idea for making money from asteroids

M-type asteroids are made of pure, or almost pure metal. Iron is the main constituent but most M-type asteroids also contain significant levels of nickel, making them into a sort of stainless steel. If the metal is pure enough these asteroids will in practice be big lumps of ready-made steel.

Steel is not much sought after by asteroid miners. Steel is too cheap on Earth to make exports in that direction very unprofitable. And modern spaceships are made from much fancier materials than steel, making it difficult to sell to the space economy as well. Some day, when humanity is ready to build giant space habitats, there will be a market in space for loads and loads of steel. But that day can be hundreds of years away for all that we know.

An alternative to selling your resources is to use them yourself and produce other sellable things. Gerard K. O'Neill, the 1970s crusader for space colonization (whose book I wrote about here), envisaged early space colonization making money from electricity production in space where the electricity was then beamed down to consumers on Earth.

Solar power in space is much simpler than solar power on Earth's surface. But it is still not uncomplicated. At least not when done on scale. And beaming great amounts of power through the atmosphere is untested and might be unfeasible or at least uneconomical. It might be, however, that the whole electricity thing is a diversion. A lot of electricity on Earth is used to produce light. It seems rather circumstantial to convert light to electricity in space, only to convert it back to light on Earth. Especially since light is much easier to relocate than electricity.

If you happen to have a great lump of stainless steel in orbit around Earth it is comparatively trivial to transform this lump into mirrors. It is mostly a matter of applying energy, readily available from the sun, to melt the metal and then reshape it into flat or slightly convex mirrors that can reflect light down to Earth. The zero gravity is actually a positive in this case since the mirrors need very little scaffolding to stay in place and stay directed at a single point on Earth's surface.

There are many points on Earth's surface that need some extra light. And there is surprisingly much money to be had supplying it. Even a geographically small country like the UK spent over a billion dollars on street lighting last year. Even though I have not been able to find corresponding numbers for other countries, the global total must be one or two magnitudes higher than that.

Reality, always the reality

Unfortunately it is not likely that the entire street lighting market will be surpassed by space lighting anytime soon. While the total market for street lighting might be gigantic it is also fragmented, supplied by millions and millions of lamp posts. Substituting millions of lamp posts will require millions of space based mirrors. And while it might be trivial to produce light-reflecting sheets of steel from a steel asteroid it is slightly more complex to rig them all up on some sort of scaffolding. Not to mention the high degree of accuracy that is needed to adjust every individual mirror to hit just the right spot down on Earth. These engineering problems can no doubt be solved. It is more doubtful if they can be solved easily and cheaply enough to make the project worthwhile.

Then there is the bane of sunbathers and space street light suppliers alike: clouds. An overcast day can easily block out 90% of incoming light and sometimes up to 99%. Bright sunlight has a luminance of 100,000 lux, significantly more than streetlights which usually produce something in the range of 5-50 lux. And since sunlight is cheap in space we could overcome this problem by just supplying more light, right? Unfortunately street lighting depends on an ability to aim the light on the streets you want to light up. One effect of overcast clouds is that they scatter the light over a wide area. Even if you supply 100,000 lux to a particular street that is no good if your light gets scattered all over the city.

Another problem is that these types of solar satellites need to be placed in a constant position above Earth. This means geostationary orbit and a geostationary orbit is always directly above the equator. Except for the equator all locations will get its mirrored light at an angle, in higher latitudes the angle will be quite steep. Street light coming from afar at an angle is generally no good. It will be blocked out by buildings meaning it is useless in many situations.

These two flaws are grave but not completely fatal to the project of solar street lighting. They limit its potential but there are still plenty of cloud-free locations close to the equator that could also use some light. I do not know how much Dubai spends on street lighting each year but I do know that they have a lot of street lights. Then there is the possibility of using easily adjustable solar mirrors to light up areas temporarily; workplaces, disaster areas or maybe sports stadiums. The possibilities are endless. 

If any of you readers are still not convinced by the arguments for space based street lighting, I understand you. I am not quite ready to invest all my savings into this either. But I do think that those who are already engaged in asteroid mining enterprises should take a serious look into this. After all, a few meteorites aside, light is the only thing that Earth gets from space. Instead of inventing something entirely new, why not just perfect the one space import there already is?