This year has certainly been all about microbes, and a new paper keeps this trend going -- but not how you'd expect.
Microbes can help extract economically-important materials from rocks in zero-gravity, a new paper reports. The findings showcase the potential of microscopic life in such applications even in space. They also point to the possibility of 'biomining' being used as a critical transition step before settling another planet.
The smallest miners
Rare earth elements are, as their name suggests, quite rare. But they're also critical for high-tech applications due to their often-unique physical and chemical properties. Due to their rarity, such elements are very challenging and expensive to mine and refine, and we're limited in how much we can produce. Demand for such materials will soon outstrip supply. One solution, however, may lie just above the skies.
Having the ability to identify and isolate rare earth elements will be extremely important for humanity as we seek to expand to other worlds -- bonus points if we can do it easily and cheaply. Microbes are already used in this role on Earth, and the new study reveals that they can work just as well in low- or zero-gravity conditions.
The team worked with three species of bacteria (Sphingomonas desiccabilis, Bacillus subtilis, and Cupriavidus metallidurans) in microgravity conditions that simulated the environment aboard the ISS or that on Mars. They measured how efficiently these could leech 14 rare earth elements from basalt rocks, which are very similar to those on the surface of the Moon and Mars. Trials on Earth were carried out in parallel with these experiments to give the team a control group in normal gravity conditions.
All in all, S. desiccabilis successfully extracted the elements from rocks in all three gravity conditions. It was quite effective across all conditions and showed the highest extraction efficiency (around 70%) of all the bacteria tested with the elements Cerium and Neodymium. The other two species were either less effective in low gravity conditions (compared to normal gravity), or were completely unable to perform the task.
The findings suggest that not all the species we use for mining here on Earth would function well, or at all, in other gravity conditions. However, they also clearly show that some of these species would. Identifying which ones these are will be a species-by-species process, but it would definitely pay off in the long term.
That being said, the idea of carrying microorganisms from Earth to another planet is quite a philosophical can of worms. While it may definitely help us extract the things we need from deposits far away, such a step risks fundamentally altering (or replacing) a celestial body's biosphere.
The paper "Space station biomining experiment demonstrates rare earth element extraction in microgravity and Mars gravity" has been published in the journal Nature Communications.
