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When you picture mining, maybe you think about pickaxes and the people wielding them, or
maybe you think about very large machines.
You probably do not picture microbes.
But it turns out tiny organisms are already hard at work in mines all over the world.
It’s called biomining.
And in a 2019 experiment, researchers sent some of these microscopic miners to the International
Space Station — a crucial step toward using biomining to explore, and eventually live,
in space.
You don’t generally find useful or valuable metals just hanging out by themselves in nature.
They tend to be mixed up with other rocks and minerals as part of ore.
Normally, to get the important stuff out, you heat up the ore, or use chemical reactions.
But in 1950, we discovered that bacteria that could lend a hand… or at least a cell.
Miners around the world have long known that flooding a copper mine and adding iron to
the water can produce copper.P03
At the time, they called this alchemy.
But turns out it was less about magic and more about the bacteria living off of the
rock.
In biomining, bacteria feed on sulfide minerals and release metals in the process.
Today, 15% of the copper and 5% of the gold on Earth is produced this way.
And there are two basic processes you can use.
In biooxidation, you use microbes to remove surrounding material, leaving behind the stuff
you’re trying to mine.
And bioleaching is kind of the opposite — microbes target the substance you’re after and dissolve
it into a liquid, which you can then separate out.
Whatever kind you use, though, biomining has a lot going for it.
Microbes can recover metals out of waste from mines or help clean up contaminated soils.
They can even help recover metals from old electronics like cell phones and computers.p06
And we know all of this works great on Earth, but it could be especially useful for mining
in space someday.
For one thing, we could bring back elements that are in short supply here on Earth — like
a group of 17 elements known as rare earth elements.
Despite the name, these elements aren’t actually all that rare on Earth.
Some of them do happen to be used in electronic devices, though, so demand is going up much
faster than supply.
We could also take advantage of biomining to supply future outposts on other worlds.
We’d need a source of metal for construction and manufacturing, but it would take tons
of fuel and other resources to load heavy mining equipment into rockets and send it
to other worlds.
With biomining, we could just bring some tiny microbes with us instead.
They could even help us turn rock into nutrient-rich soil for farming.
That is, if biomining works out there.
See, the places we’d probably settle first, like Mars and the Moon, have much lower gravity
than Earth.
The jury is still out on whether bacteria can sense a change in gravity, but we know
it can affect how microbes grow — because it changes the way things move and flow within
cells.
And that’s where the BioRock experiment comes in.
In July 2019, the European Space Agency sent teams of microbial astronaut miners to the
International Space Station to see how they fared in different gravity conditions.
They selected three types of bacteria that could interact with rock and leach out metals,
and tested each under three levels of gravity: weightlessness, Mars’s gravity, and Earth
gravity.
To simulate these, they spun up the bacteria in a centrifuge.
Being on the Space Station, everything starts at essentially zero gravity, but by spinning
the experiment, they were able to use centrifugal force to simulate different amounts of gravitational
The faster you spin them, the more artificial gravity they’re subjected to.
It’s like those rides at the fair that spin really fast and make you stick to the wall,
and you could stand up in there if you weren’t strapped down, and then you vomit.
The goal was to see how well the microbes could leach out rare earth elements from a
type of rock called basalt — because there is lots of basalt on the Moon and Mars.
After leaving the experiments in space for 21 days, they shipped them back to Earth to
see how well each team of microbes did.
One type of bacteria was unaffected by changes in gravity and did a great job of extracting
elements in every set of conditions.
A second type was less efficient in lower gravity, and for some reason, the third didn’t
end up working at all… even in Earth gravity.
So there’s still more work to be done before we’re ready to set up a biomining operation
on another world.
Luckily, we probably have some time to figure it out, since it doesn’t seem like we’ll
be starting an off-world colony any time soon.
But thanks to the BioRock experiment, we now know that biomining in space could work — we
just need to find the right microbes for the job.
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