Mining is a messy process. It takes a lot of effort to break open rocks to get the materials needed to keep our current technological level on earth. The march of technology has produced some massive leaps and bounds in communication and quality of life improvements. However, most of these are predicated on the availability of difficult-to-find elements. From smartphones to microwaves, and even electrical power plants need large volumes of minerals. Anglo American explains that biomining, also known as bioleaching, is a process that uses microbes to extract minerals from the earth. The process generates significantly less pollution than traditional mining methods and makes for a unique way of getting metals to the surface of the planet. Some organizations have also used bioleaching to clean up mining sites that are no longer being used. Aside from the process's obvious usefulness here, it has a far more practical application in space.
Asteroid Mining with Bacteria?
One of the core components of our modern lifestyle that is under threat is the availability of rare-earth metals. While these aren't actually "rare," the name is fitting because they are difficult to extract and are usually found in compounds with other materials. The extraction method for rare-earth metals can lead to massive amounts of pollution. Additionally, since getting to these materials is challenging, they're relatively expensive. It's one of the reasons why expensive electronics prices won't see a meaningful decrease. The South China Morning Post mentions that China supplies 85% of the world's rare-earth metals, a concern for many countries in the West. However, as rare as these metals are on earth, they are abundant in asteroids and other planets within the solar system.
The problem with mining those metals out in space is that the typical material, staffing, and resources needed would cost more to get into space than they would bring on return. Low-tech mining might work if we already had an established moon base, but with each other planet we had to go to, the logistics would lead to even more money being spent just to catch up with demand. Biomining is one solution, but the concern has always been that the microbes used in biomining may not interact well with a zero-gravity environment. For biomining outside of the earth's atmosphere to make sense, we must first see if microbes can survive and thrive in low-gravity environments.
The Vanadium Test
One of the more useful rare-earth metals that we have access to is vanadium (V) and is used in construction materials and tools to add strength to standard steel. A paper published in Frontiers in Microbiology delves into the question of whether vanadium can be biomined in low-gravity settings. The scientists collected basalt, an igneous rock, that showed signs of having vanadium within it. Using ICP-MS (inductively coupled plasma mass spectrometry), the team determined that the basalt did indeed contain vanadium. The basalts chosen for this experiment were similar to those that one would find on the moon or Mars. The rocks were sterilized by high-heat application, which did not change the internal mineralogy of the stone as determined by X-ray diffraction performed before and after the sterilization.
The bacteria used in this study aren't by any means something that the average reader would recognize. Bacillus subtilis and Sphingomonas desiccabilis are both harmless microorganisms that no one even knows exist. They spend a lot of their time on basalt rock and soil, tirelessly processing crusts on the Colorado Plateau. S. dessicabilis is also used in promoting positive gut health. However, these microorganisms both "consume" rocks, among them basalt. The thinking is that, with the bacteria consuming the rock, the remaining compound would be vanadium. Testing this hypothesis would take a specialized experiment.
To ensure that the experiment took into account the rigors of space, the samples were put onto a SpaceX Dragon capsule and launched into space. They were collected by the ISS and kept under observation for twenty-one (21) days in several variations of gravity produced by a centrifuge attached to the KUBIK incubators used for the test. As a control, a ground test was also run in tandem with those on the ISS, using a similar setup but run at 1g (earth gravity). The comparison of the results showed no significant difference between the low-gravity test and the one done on earth, suggesting that biomining might be a viable way to approach getting rare-earth metals from an asteroid or another planet.
The Wonders of Biomining to Save our Planet
Previous research in microgravity experiments has shown scientists that tiny organisms may behave differently when in low-gravity environments. Research has shown that DNA can auto-reform in microgravity, providing an avenue of study for healing degenerative diseases such as cancer. The experiment sought to determine whether biomining would be affected by this microgravity, and the result was a resounding no. But where does that leave us in our eternal search for rare-earth metals? Does it work for other rare-earth metals like Lanthanum and Yttrium? The chances are that these methods will also work with other rare-earth metals since they already function with metals like gold and silver. Without risking human life to mine these metals, we create a much safer work environment for individuals dealing with ore extraction. However, the benefits to the planet are much more significant than this.
Mining creates a lot of problems for the benefits it gives to us. Industrial mines leave behind massive tailings that contain slurry that would be dangerous if released into the environment. Aside from that, these mining operations routinely spew out tons of greenhouse gases, adding to the issue of global warming. Since many of these mines operate in third-world countries with little oversight for environmental abuses, their emissions continue unchecked. The hope is that by applying these microbes to other planets and the surfaces of asteroids, we can preserve the earth we have here and stop extracting its natural resources. The realizing of this plan may be a while off, but this research is a step in the right direction.