The Search for Life is focused on the search for biosignatures. Planetary life leaves a chemical fingerprint on a planet’s atmosphere, and scientists are trying to work out which chemicals in what combinations and amounts are a surefire indicator of life.But new evidence suggests that super-tiny amounts of DNA can be detected in Martian rocks if it’s there. And though it requires physical samples rather than remote sensing, it’s still an intriguing development.
“Investigating active life forms in extremely low biomass environments is a topic of interest for expanding our knowledge of Earth’s biodiversity and the search for life on Mars,” the authors write. “We aim to push the technology even further for when the Mars Sample Return mission returns in 2033.”Scientists often turn to analogue Martian environments here on Earth to test ideas and equipment. One of them is the Atacama Desert in Chile, “one of the best Martian analogue environments due to its extreme aridity,” according to the authors. On Mars, the Perseverance Rover is collecting samples for return to Earth.
The team set out to define new limits of concentration for DNA sequencing. The results could be applied to diverse fields, but the focus is on the eventual return of Mars Samples to Earth. There’s an assumption that any Mars life will use DNA just as Earth life does. In other words, “it relies on the same chemical processes as terrestrial organisms, and it codes its genetic information with the known bases that are ubiquitously used by life on Earth,” the authors explain.
The research team pushed MinION even further. They diluted some samples even further and tested them with the device. The results were even more impressive. “We ran two replicates per sample type, and the MinION sequencer successfully detected the microbial taxa at 2 pg in both experiments,” the paper states. “This is the lowest limit detected so far.”
It not only means that it can identify life forms in samples with extremely low biomasses, but it also means it can detect ambient contamination from Earth.