A new investigation by University researchers on the International Space Station is asking the question: could we unleash microbes to mine rocks in space?
For centuries, people have done the hard work of mining useful minerals and metals from solid rock. Then, scientists learned how to harness the power of tiny microbes to do some of this labour for them. The process, known as biomining, has now become commonplace on Earth.
As humans plan expeditions to places such as the Moon and Mars, biomining offers a way to obtain needed materials on other planetary bodies rather than bringing them from Earth. This approach is called in-situ resource utilisation. However, microbes and rocks interact differently outside of Earth's gravity, potentially affecting the output from extra-terrestrial biomining.
A new investigation on the International Space Station represents the first study of how microbes grow on and alter planetary rocks in microgravity and simulated Martian gravity. The study, BioRock, is also the first test of extra-terrestrial biomining and the first use of a prototype miniature mining reactor in space.
"We're studying three types of microbes, giving us the first comparison between behaviours of different microbes in the space environment," says Professor Charles Cockell, Chair of Astrobiology at the UK Centre for Astrobiology at the University of Edinburgh. "Scientists know very little about how microgravity affects microbe and mineral interactions, but previous research demonstrates that the attachment of microbes to surfaces, or formation of biofilms, occurs differently in space.
“In general, biofilms increase, grow thicker and show particular shapes and structures in microgravity. We expect to see similar behaviour by the microbes in the BioRock investigation.”
Pieces of the puzzle
For the investigation, Professor Cockell and his team are using basalt rock that is naturally very vesicular, or contains lots of spaces, to see how the bacteria interact within these cavities in microgravity. Basalt also makes up most of the crust of the Moon and Mars. Back on Earth, researchers will then examine how the microbes grew across and into the rock and will compare the three types of microbes.
They also will look at the elements leached into the fluid around the rock, and examine how well the different microbes extracted more than 20 different elements from the rocks. The three microbes include one isolated from desert crusts in the western United States Colorado Plateau, one provided by the German Aerospace Centre, and another known for its resistance to heavy metals provided by the Belgium Nuclear Research Centre.
"The BioRock experiment starts putting the pieces of the puzzle together," says Professor Cockell. "Understanding how microbes interact, grow and extract elements from a rock surface in microgravity and simulated Mars gravity will tell us, for the first time, if low gravity affects the ability of microorganisms to attach to rock surfaces and perform biomining. In other words, whether extra-terrestrial mining is possible."
The results should provide qualitative and quantitative comparison of bacterial and rock interactions taking place at terrestrial gravity, simulated Martian gravity, and microgravity levels. Bacteria could be the key to turning the surfaces of desolate worlds such as the Moon or Mars into fertile farmland where visitors or colonists could grow their own food. That would, again, majorly cut down on the amount of food needed for long-term missions, while also providing much-needed variety and nutrition that are difficult to provide in space rations today.
"We hope to gain insights into how microbes grow in space and how we might use them in human exploration and settlement of space, from mining to turning rocks into soils on the Moon and Mars," says Professor Cockell. “Microbe-rock interactions can turn rock into soils and explorers might one day use them to transform regolith - the layer of dusty, fragmented debris covering the surface of the Moon, Mars, and asteroids - into soils for growing plants.”
The BioRock experiment is designed to last three weeks, after which the reactors will be sent back to Earth for study at Stanford University. Upon completion, the team already has plans for future experiments. They hope to study more microbes and materials, allowing them to try out different combinations to find the right microbes for the job, no matter where in the solar system that work might take them — and us.
"Microbes are everywhere - in our food, our homes, and our industrial processes - and they do hugely important things in our everyday life," says Professor Cockell. "As we move into space, we can harness microbes to make our lives easier and improve the success of space settlements. BioRock is about forming a new space-faring alliance with the microbial world - using microbes to advance a permanent human presence in space."
And letting the tiny organisms do some of the hard work.