Within the next decade, space agencies aim to bring back rock samples from Mars for examination on Earth. A major concern surrounding these missions is the potential presence of extraterrestrial microbes, which could pose unknown risks. To mitigate such concerns, scientists are developing advanced methods to detect life. For the first time, researchers from the University of Tokyo and NASA have by Riko Seibo
Tokyo, Japan (SPX) Mar 13, 2025
Within the next decade, space agencies aim to bring back rock samples from Mars for examination on Earth. A major concern surrounding these missions is the potential presence of extraterrestrial microbes, which could pose unknown risks. To mitigate such concerns, scientists are developing advanced methods to detect life. For the first time, researchers from the University of Tokyo and NASA have successfully demonstrated a technique capable of identifying life in ancient rocks that share similarities with those expected from Mars.
Science fiction has long entertained the idea of alien organisms hitching a ride to Earth, often with disastrous consequences. While such scenarios make for thrilling storytelling, the real-world concern of planetary contamination is a longstanding one. During the Apollo program, astronauts who landed on the Moon were quarantined upon their return as a precautionary measure. Today, with multiple missions planned to retrieve Martian samples, scientists are taking similar precautions.
To prevent the risk of contamination, the Committee on Space Research (COSPAR) has developed a rigorous framework for evaluating the safety of extraterrestrial samples. This framework establishes protocols for collecting, transporting, and analyzing Martian material while minimizing the risk of cross-contamination with Earth's biosphere. A crucial part of this process is the ability to determine whether a sample contains any biological material. However, since no Martian samples have yet been returned, researchers must refine their detection methods using Earth-based analogues.
Associate Professor Yohey Suzuki from the University of Tokyo's Department of Earth and Planetary Science, along with an international research team, turned to ancient microbe-rich rocks from Earth that resemble the basaltic formations expected on Mars. Their goal was to identify a reliable technique to detect life within these samples.
"We first tested conventional analytical instruments, but none could detect microbial cells in the 100-million-year-old basalt rock we use as the Martian analogue. So, we had to find an instrument sensitive enough to detect microbial cells, and ideally in a nondestructive way, given the rarity of the samples we may soon see," said Suzuki. "We came up with optical photothermal infrared (O-PTIR) spectroscopy, which succeeded where other techniques either lacked precision or required too much destruction of the samples."
The O-PTIR method involves exposing the rock samples to infrared light after removing their outer layers and slicing them into thin sections. Although this process is slightly destructive, it preserves most of the material for further examination. A green laser then scans the exposed sections, detecting signals that reveal structural details as small as half a micrometer-small enough to identify microbial traces.
"We demonstrated our new method can detect microbes from 100-million-year-old basalt rock. But we need to extend the validity of the instrument to older basalt rock, around 2 billion years old, similar to those the Perseverance rover on Mars has already sampled," Suzuki explained. "I also need to test other rock types such as carbonates, which are common on Mars and here on Earth often contain life as well. It's an exciting time to work in this field. It might only be a matter of years before we can finally answer one of the greatest questions ever asked."
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