Building An Extra-terrestrial Habitat - One Microbe At A Time

This fluorescent work of art captures the beauty of biofilms, or the growth of microbes on rocks. In this microscopic image, Sphingomonas desiccabilis is growing on basalt. It is one of three microbes chosen for the BioRock experiment, run by a research team from the University of Edinburgh in the UK, that will test how altered states of gravity affect biofilm formation on the International Space Station. More

We are making good progress towards going to the Moon and Mars.

We are building new spacecraft, bringing astronauts to the International Space Station for extended stays and sending robots to Mars. To build a sustainable presence on these planetary bodies however, we also need local resources. Resources that may or may not be readily available on the Moon and Mars.

An important example of such resources are metals also referred to as rare Earth elements. These are often used in the production of electronics such as computer screens, metal alloys and magnet production - vital materials for building a lunar or Martian base.

Taking these building blocks with us on a spacecraft is not an option. It would be too heavy, and too expensive to take these rare elements with us from the already much-depleted Earth.

As it turns out, precious metals are present on the Moon and Mars, but they are embedded within the rock and soil, making it difficult to use them. Bringing mining equipment would, again, be too heavy and expensive to bring from Earth, and the machinery would have to be completely redesigned for use in such an inhospitable environment.

ESA's BioRock project has been working on a solution: biomining in space. Bringing the world's tiniest miners to do the extraction for us.

Biomining uses microbes to leach off the rocks and "eat" the rare Earth elements. The metals can then be extracted from the microbes, and used for further processing. This method has been used successfully on Earth for years. But could this work in space?

Promising research results

The BioRock experiment set out to find some answers. In an experiment performed on the International Space Station by ESA astronaut Luca Parmitano, three strains of biomining bacteria were flown to space to test how they would perform in different gravitational conditions.

The bacterial strains were left to grow inside Europe's weightless laboratory Columbus on one of their favourite surfaces, basalt rock. This is a type of rock found on the Moon and on Mars, known to contain rare Earth elements. The samples were left to grow in three levels of gravity: microgravity, Moon gravity (0.38 g) and simulated Earth gravity in the Kubik centrifuge facility.

After 21 days, the cell populations were sent back to Earth for analysis. The BioRock team discovered that none of the three populations suffered any significant negative effects in any of the gravitational conditions. This showed they had grown just as well in simulated Earth gravity, Moon gravity and microgravity. The researchers then analysed if the amount of elements mined by the bacteria was influenced by the different gravity conditions. Two strains of bacteria ate as much as they would have on Earth yielding roughly the same amount of rare elements.

The fact that these three bacteria could survive, and even thrive, in gravity conditions such as in lower Earth orbit or on the Moon is "a really exciting result" according to Nicol Caplin, Exobiology Research Fellow at ESA and BioRock project coordinator. It shows that we don't need to mitigate different gravity variations when using these biomining bacteria off the Earth and biomining could in fact prove to be a great way to extract rare Earth elements on the Moon and Mars.

These positive results have now been published in Frontiers in Microbiology and in Nature. The BioRock team is not resting on their laurels, however. They are already working on the next research proposals. Bringing us closer to building a Moon and Mars habitat - one microbe at a time.

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