Asteroids are the new gold mines. Fly to an asteroid, dig up its minerals, become a billionaire. I used to think this was crazy and will never make sense financially. But after reading a lot, I now think that maybe it works – by letting bacteria do the digging. How do you dig with bacteria? Is it even legal to mine asteroids? And will it happen in your life? That’s what we’re going to talk about today.
Space agencies like NASA and ESA have found around 25,000 asteroids. In 2020 alone, they discovered 3,000 new near-Earth asteroids. About 900 of them have an extension of 1 kilometer or more.
What makes asteroids so interesting for mining is that their chemical composition is often similar to that found in the core of our planet. Platinum group metals are very expensive because they are useful but rare in the earth’s crust. On an asteroid, they can be much easier to dig out. And that’s an easy way to get rich – very, very rich.
The asteroid Psyche, for example, is about two hundred kilometers in diameter, and astrophysicists estimate that it is about ninety percent metal, mostly iron and nickel. Lindy Elkins-Tanton, chief scientist for NASA’s Psyche Mission, estimated the asteroid to be worth about $ 10 trillion. This is a 1 followed by 19 zeros. Now imagine if that thing was made of platinum …
By the way, NASA is planning a mission to Psyche, which should start in 2022. Not because of the trillions, but because they want to study its composition to learn more about how planetary systems are formed.
How do you find an asteroid that is good for mining? Well, at first it shouldn’t take forever to get there, so you want one that gets reasonably close to Earth every now and then. You also don’t want it to spin too much as that would make it very difficult to land or operate. And finally you also want one that is cheap to get to, that needs a little acceleration during the flight, a little “Delta V” as it is called.
How many asteroids are there that meet these requirements? The Harvard astrophysicist Martin Elvis estimated it using an equation now known as the Elvis equation. It is similar to the Drake equation, which is used to estimate the number of extraterrestrial civilizations by multiplying many factors. And like the Drake equation, the Elvis equation is heavily dependent on the assumptions you make.
In any case, Elvis estimates with his Elvis equation that only about 10 of the known asteroids are worth mining. With the others, the cost-benefit ratio is not right because they are either too difficult to achieve or not worth enough mining or are too small. In principle, one could also think of catching small asteroids and bringing them back to Earth, but in practice this is difficult: the small ones are difficult to find and track. At least for the moment it doesn’t work.
So the first two problems with asteroid mining is how to find an asteroid and get there. The next problem is digging. The gravitational pull on these asteroids is so weak that you can’t just drill into the ground, but simply push the spaceship off the asteroid.
Perhaps the most obvious way to get around this problem is to anchor the digging machine to the asteroid. Another solution NASA researchers are pursuing is shovels that dig in two opposite directions at the same time, so there is no net force to knock the machine off the asteroid. NASA is also looking into the possibility of using a swarm of small robots instead of a large machine to coordinate their tasks.
Another smart idea is optical digging. Use mirrors and lenses to focus sunlight to heat the surface. This allows the surface to be burned off layer by layer and the material can then be collected in bags.
And then there is mining with bacteria. Using bacteria for mining is actually not a new idea. It’s called “biomining,” and according to some historians, the Romans did it 2,000 years ago – although they almost certainly didn’t understand how it worked, as they didn’t know about bacteria from the start. But we now know that some bacteria eat and break down minerals. And during their digestive process, they separate off the metal that you want to extract. So basically the idea is you send the bacteria to your asteroid, let them eat the dust, and wait for them to be digested.
On earth, biomining is responsible for about twenty percent of global copper production and five percent of global gold production. But how can bacteria survive on asteroids? You’re not very good at tucking them into spacesuits!
For one thing, you wouldn’t throw the bacteria directly at the asteroid, but put it in some kind of gel. Still, the conditions on an asteroid are pretty harsh and you need to find the right bacteria for the job. It’s not hopeless. Microbiologists know that some types of bacteria have adapted to temperatures that would easily kill humans. For example, some bacteria can live at temperatures of up to one hundred and thirteen degrees Celsius, others at temperatures as low as minus twenty-eight degrees Celsius. At low metabolic rates, they can even survive at minus forty degrees. And some types of bacteria survive a vacuum of as little as 10 to minus five pascals, which should allow them to survive near a spacecraft.
What about radiation? Here, too, bacteria are remarkably resistant. The bacterium Deinococcus radiodurans, for example, can withstand ionizing radiation of up to twenty kilograys. For comparison: In humans, acute radiation poisoning sets in at about zero point seven gray. The bacteria can easily tolerate twenty thousand times as much!
And while the perfect bacteria for space mining has not yet been found, there is a lot of research going on in this area. This looks like a really promising idea to me.
But you might be wondering now, is it even legal to mine an asteroid? Probably yes. This type of question is addressed by the nineteen sixty-sixty-seven space treaty signed by one hundred and eleven countries, including the United States, Russia, and almost all of Europe.
According to this treaty, celestial bodies may not be subject to “national appropriation”. However, the treaty does not deal directly with the extraction of “space resources,” these are things that you will find on these celestial bodies. Some countries have interpreted this to mean that commercial mining is not a national appropriation and is allowed.
For example, since 2015, American citizens have had the right to own and sell space resources. Luxembourg created a similar legal framework in 2017. Russia is also about to pass such a law.
This isn’t the only development in the area. You can now get a university degree in space resources, for example from the Colorado School of Mines, the University of Central Florida and the University of Luxembourg. At the same time, several space agencies are planning to visit other asteroids. NASA not only wants to fly to Psyche, but also to Bennu, which is expected to come close to Earth on September 23rd.
The Chinese National Space Agency has proposed a similar mission to collect a sample from the asteroid Kamo’oalewa. And there are several other missions on the horizon.
And then there is industry interest. About a decade ago, a number of start-ups emerged with the goal of mining asteroids, such as Planetary Resources and Deep Space Industries. These companies attracted some investors when they showed up, but have since struggled to attract more money, and they have basically disappeared – they were bought by other companies more interested in their assets than promoting the asteroid mining adventure .
The problem is that asteroid mining is a real business, but it’s a business that still has a lot of research to be done: how to tell which asteroid is a good target, how to get to the asteroid, how to dig on it. And let’s not forget that once you’ve done that, you have to bring the stuff back down to earth. It would take billions of upfront investments and decades to pay off even at best. While it looks promising, it seems unlikely to me that private investors will drive technology development in this area. It will likely be left to tax-funded space agencies to fund this research for much longer.