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If humanity wants to explore deep space and live on other planets, we must bring parts of Earth's environment with us. This need includes complex systems called Bioregenerative Life Support Systems (BLSS). These systems use biological processes to keep humans alive by cleaning the air and recycling water. To work properly, they depend on many different species of tiny microbes. Humans already carry these organisms with them when traveling to space, especially to the International Space Station (ISS). These microscopic life forms become part of the natural environment on the station. They stick to surfaces, grow in hidden spots, and eventually settle into everything within the spacecraft.
Because these microbes are always present, it is critical that scientists understand how they survive in the unique conditions of space. Beyond just surviving, these organisms might have special uses that could allow astronauts to become more self-sufficient during long missions. Certain types of bacteria and fungi are known to pull minerals out of rocks to use as nutrients. In a recent study on the ISS, researchers from Cornell University and the University of Edinburgh tested how these species could extract platinum from a meteorite while in microgravity. Their results suggest this method could be highly effective for gathering resources in space. It could also significantly reduce humanity's need to bring supplies from Earth.
This study was led by Rosa Santomartino, an assistant professor at Cornell, and Alessandro Stirpe, a research associate at both Cornell and the University of Edinburgh. They worked with a team of researchers from institutions in Austria, the United Kingdom, and the United States. Their findings were published on January 30th in the scientific journal npj Microgravity.
This work was part of the BioAsteroid project, a major collaboration between the University of Edinburgh and the European Space Agency (ESA). The project was led by Charles Cockell, a professor of astrobiology at Edinburgh, who was a senior author on the study. Cockell and his colleagues developed special "biomining reactors" that were sent to the ISS in late 2020 and early 2021. The main goal was to see how gravity affects the interaction between microbes and rock when the pull of gravity is removed, a condition known as microgravity.
The reactors held samples of an L-chondrite asteroid, a type of rocky body that has traveled through space for billions of years. Scientists treated these samples with the bacterium Sphingomonas desiccabilis and the fungus Penicillium simplicissimum. These specific microbes are considered promising for resource extraction because they produce carboxylic acids. These acids bind to minerals and help release them from the surrounding rock. However, there is still some scientific uncertainty about exactly how this chemical process works in the vacuum of space. To learn more, the experiment included a metabolomic analysis. Researchers extracted a part of the liquid culture and analyzed it for specific biomolecules to understand the biological changes happening inside.
Rosa Santomartino explained the importance of the study in a press release. She noted the unique nature of their work and stated, "This is probably the first experiment of its kind on the International Space Station on a meteorite." She continued by explaining that they wanted to keep the approach tailored to the specific experiment but also general enough to increase its impact. "These are two completely different species, and they will extract different things," she said. "So we wanted to understand what and how, but keep the results relevant to a broader perspective, because not much is known about the mechanisms that influence microbial behavior in space."
The experiment was physically conducted aboard the ISS by NASA astronaut Michael Scott Hopkins. At the same time, the research team ran a control version of the experiment in a laboratory on Earth. This setup allowed them to directly compare how the experiment worked in microgravity versus the constant pull of Earth's gravity.
Santomartino and Stirpe then analyzed the data collected from the experiment. The analysis showed that out of 44 different elements tested, 18 were successfully extracted through these biological processes. Alessandro Stirpe described their analytical process, noting the complexity of the data. He said, "We split the analysis to the single element, and we started to ask, OK, does the extraction behave differently in space compared to Earth? Are these elements more extracted when we have a bacterium or a fungus, or when we have both of them? Is this just noise, or can we see something that maybe makes a bit of sense?" Stirpe added, "We don't see massive differences, but there are some very interesting ones."
Their detailed analysis showed that the microbes produced consistent results in both Earth gravity and the microgravity of space. However, the study also revealed distinct changes in microbial metabolism, especially in the fungus samples. In the microgravity environment, the fungus increased its production of carboxylic acids and other molecules. This chemical change led to the extraction of more elements, including valuable metals like palladium and platinum.
Meanwhile, the non-biological leaching experiment, which involved no microbes, proved to be less effective in microgravity than it was on Earth. This suggests that the biological process offers a unique advantage in space. Santomartino elaborated on this complex result, explaining that in these cases, the microbe does not necessarily improve the extraction rate itself. Instead, it keeps the extraction at a steady level, regardless of the gravity condition. She noted, "And this is not just true for the palladium, but for different types of metals, although not all of them. Indeed, another complex but very interesting result is that the extraction rate varies a lot depending on the metal you are considering and on the microbe and gravity conditions."
This experiment has successfully demonstrated the potential for "biomining," a process that uses biology to extract minerals. Future astronauts exploring the Moon and Mars could use this technique to gather resources locally. In addition to life support systems that rely on organisms to clean the air and generate food, microbes and fungi could be used to extract minerals from local soil and rock. These minerals could then be used to generate building materials for structures and tools. This would significantly reduce the amount of supplies that need to be sent from Earth, making long-duration missions more feasible.
Biomining also has potential applications here on Earth. It could provide a biological way to extract metals in resource-limited environments or from old mine waste. This technique could also lead to new biotechnologies that support a zero-waste, circular economy, helping to protect our planet.
However, the research team cautions that more study is required. There are many variables and uncertainties regarding the impact space has on microbes. "Depending on the microbial species, depending on the space conditions, depending on the method that researchers are using, everything changes," Santomartino said. "Bacteria and fungi are all so diverse, one to each other, and the space condition is so complex that, at present, you cannot give a single answer. So maybe we need to dig more. I don't mean to be too poetic, but to me, this is a little bit the beauty of that. It's very complex. And I like it."
The journey to deep space requires not only advanced engineering but also a deep understanding of the microscopic life that can help us survive. This study proves that life itself, in the form of bacteria and fungi, might be our best tool for building a future among the stars.