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Obtaining minerals in space may be a little easier than we thought – with the help of some of Earth’s smallest inhabitants.
Experiments aboard the International Space Station have shown that bacteria can improve the efficiency of space extraction by over 400%, providing a much easier way to access materials such as magnesium, iron and rare earth minerals that we use widely in electronics and alloys.
Here on Earth bacteria play a very important role in extracting minerals from the soil. They are involved in the natural weathering and degradation of rocks, releasing the minerals they contain.
This bacterial capacity to leach metals from their environment has been used to facilitate human mining operations; Called biomining, it has a number of advantages. This can help reduce dependence on cyanide for gold mining, for example. Bacteria can also help decontaminate polluted soils.
In space environments, such as asteroids, the Moon, and even Mars, mining will be a valuable tool when we set up human outposts. Transporting material from Earth is expensive; even the cheapest option, SpaceX’s Falcon Heavy, costs US $ 1,500 per kilogram (2.2 pounds) of payload. Scientists therefore studied the feasibility of bio-extraction in space.
“Microorganisms are very versatile and as we move through space they can be used to accomplish a variety of processes,” said astrobiologist Rosa Santomartino from the University of Edinburgh in the UK. . “Elemental mining is potentially one of them.”
Over a period of 10 years, the team developed a small device the size of a matchbox called a biomining reactor that could be easily transported and installed on the International Space Station. Then, in July 2019, 18 of these biomining reactors were shipped to the ISS for low Earth orbit experiments.
(Cockell et al., Nature Communications, 2020)
Each biomining reactor contained a bacterial solution that submerged a small piece of basalt, a type of volcanic rock abundant on the Moon. For a period of three weeks, the basalt from each reactor was exposed to the bacterial solution to determine if the bacteria could perform the same weathering function of rocks in a low gravity environment.
In simulated Mars gravity, simulated Earth gravity (using a centrifuge), and microgravity, the team performed experiments with separate solutions of three different bacteria: Sphingomonas desiccabilis, Bacillus subtilis and Cupriavidus metal durans. A bacteria-free control solution was used as a reference.
The researchers found that there were no significant differences in bacterial leaching performance depending on the severity conditions, and for B. subtilis and C. metallidurans, the extraction of rare earth minerals was lower and not significantly different from the control solution, respectively.
However, the S. desiccabilis The solution removed many more rare earth minerals from the basalt than the control solution.
“For S. desiccabilis, in all rare earth elements and under the three conditions of gravity of the ISS, the organism had leached from 111.9% to 429.2% of non-biological controls, ”the researchers wrote in their article.
As microgravity has been shown to influence microbial processes, the similarity between the concentrations of minerals extracted under the three gravity conditions was somewhat surprising. However, the team noted that all three bacteria reached similar concentrations under all three conditions of gravity, likely because they had enough nutrients to do so.
They concluded that with enough nutrients, biomining is therefore possible under a range of gravity conditions.
“Our experiments support the scientific and technical feasibility of biologically enhanced elemental mining across the solar system,” said astrobiologist Charles Cockell of the University of Edinburgh.
“While it is not economically viable to harness these elements in space and bring them to Earth, space biomining could potentially support an autonomous human presence in space.
“For example, our results suggest that the construction of robotic and anthropogenic mines in the Oceanus Procellarum region of the Moon, which contains rocks rich in rare earth elements, could be a successful direction of human scientific and economic development. beyond Earth. . “
The research was published in Nature communications.
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