Minerals in space can be a little easier than imagined – with the help of some of Earth's tiniest inhabitants.
Experiments aboard the International Space Station have shown that bacteria can increase the efficiency of mining in space by more than 400 percent, offering a much easier way to access materials such as magnesium, iron, and rare earth minerals, which are widely used in electronics and alloy manufacturing. .
Here on Earth, bacteria play a very important role in extracting minerals from the earth. They participate in the natural weathering and destruction of rocks, releasing the minerals they contain.
This ability of bacteria to leach metals from the environment has been exploited in mining operations; called biomining, it has several advantages. This can help, for example, reduce reliance on cyanide in gold mining. Bacteria can also help decontaminate contaminated soil.
In space environments such as asteroids, the Moon and even Mars, mining will be a valuable tool as we build human outposts. Delivering materials from Earth is expensive; even the cheapest option, SpaceX's Falcon Heavy, costs $ 1,500 per kilogram of payload. Therefore, scientists have studied the possibility of bio-production in space.
“Microorganisms are very diverse, and as we move into space, they can be used to perform many processes,” explained astrobiologist Rosa Santomartino of the University of Edinburgh in the UK. “Elemental mining is potentially one of them.”
For 10 years, the team developed a small matchbox-sized device called a bioprospecting reactor that could be easily transported and installed on the International Space Station. Then, in July 2019, 18 of these bioprospecting reactors were sent to the ISS for experiments in low Earth orbit.
Each biomass reactor contained a bacterial solution into which a small chunk of basalt, a volcanic rock abundant on the moon, was submerged. Over a three-week period, the basalt was exposed to a bacterial solution to determine if the bacteria could perform the same function of weathering rocks in low-gravity conditions.
In simulating Mars gravity, simulating Earth's gravity (using a centrifuge), and microgravity, the team experimented with separate solutions of three different bacteria: Sphingomonas desiccabilis, Bacillus subtilis, and Cupriavidus metallidurans. A control solution without bacteria was used as a baseline.
The researchers found that there was no significant difference in bacterial leaching efficiency depending on gravity conditions, and for B. subtilis and C. Metallidurans, the REE recovery was lower and not significantly different from the control solution, respectively.
However, the S. desiccabilis solution removed significantly more rare earth minerals from the basalt than the control solution.
“For S. desiccabilis, in all the individual rare earths and under all three gravitational conditions on the ISS, the organism leached from 111.9% to 429.2% of non-biological controls,” the researchers wrote in their paper.
(Cockell et al., Nature Communications, 2020).
Since it was previously shown that microgravity affects microbial processes, the similarity between the concentrations of minerals extracted under all three conditions of gravity is surprising. However, the team noted that all three bacteria achieved the same concentrations under all three conditions of gravity, probably because they had enough nutrients to do so.
They concluded that with enough nutrients, biodiversity is possible under a variety of gravity conditions.
“Our experiments confirm the scientific and technical feasibility of biologically enhanced mining of elementary resources in the solar system,” said astrobiologist Charles Cockell of the University of Edinburgh.
While it is not economically feasible to mine these elements in space and bring them to Earth, space bio-mining has the potential to support a self-sustaining human presence in space.
For example, our results show that the construction of robotic and manned mines in the region of the Moon Oceanus Procellarum, where there are rocks with high concentrations of rare earth elements, could be one of the fruitful directions of the scientific and economic development of mankind outside the Earth. '
The research is published in Nature Communications.
Sources: Photo: The bacterium Sphingomonas desiccabilis growing on basalt is visible on the right in the naturally porous rock used in the Biorock study. Credits: Rosa Santomartino, UK Center for Astrobiology / University of Edinburgh
