Rovers sent to Mars have so far failed to detect life, likely because it doesn’t exist on the Red Planet. But we can’t say for certain, so the search must continue, using ever-evolving techniques—including this out-of-the-box idea from a team of scientists.
As detailed in a study published today in Frontiers in Astronomy and Space Sciences, astrobiologists from Germany and Portugal shown that three species of microbes are attracted by and will move toward an amino acid called L-serine. A process known as chemotaxis—an organism’s movement in response to a chemical—could be the basis for a simple new approach in our search for tiny extraterrestrial life in places such as Mars.
“Given that early Earth and Mars were bombarded by carbonaceous asteroids, L-serine likely exists on Mars,” the researchers wrote in the study. Previous research has already shown that L-serine invokes chemotaxis in some life forms. “If life developed on Mars with a similar biochemistry to known life on Earth, it seems plausible that L-serine could also be a potent chemoattractant for hypothetical Martian microbes.”
Due to the exceptionally harsh conditions at the Martian surface, the researchers used “hypothetical Martian microbes” known for surviving harsh conditions—organisms often called extremophiles. Their stand-ins included the bacteria Bacillus subtilis and Pseudoalteromonas haloplanktis, as well as the archaea Haloferax volcanii.
“Bacteria and archaea are two of the oldest forms of life on Earth, but they move in different ways and evolved motility systems independently from each other,” Max Riekeles, an aerospace engineer at the Technical University of Berlin and co-author on the study, said in a Frontiers statement. Motility is a small organism’s ability to move independently. “By testing both groups, we can make life detection methods more reliable for space missions.”
A new method to detect tiny extraterrestrial life, based on chemotaxis. 2025 Riekeles, Bruder, Adams, Santos and Schulze-Makuch CC BY 4.0 © 2025 Riekeles, Bruder, Adams, Santos and Schulze-Makuch CC BY 4.0In order to give their approach the highest chances of succeeding on future space missions, another important aspect of the study was simplicity. Their equipment included a slide (a flat piece of glass) separated into two chambers by a thin membrane. They put the microbes in one chamber, L-serine in the other, and waited.
“If the microbes are alive and able to move, they swim toward the L-serine through the membrane,” Riekeles explained. Fortunately, that’s exactly what happened, suggesting that future astronauts could use this method to identify the presence of similar microorganisms in extraterrestrial samples. According to the study, this is normally difficult to achieve even with advanced microscopic techniques.
“This method is easy, affordable, and doesn’t require powerful computers to analyze the results,” he added.
Though real life applications of this method on future space missions would have to make use of an automatic system with smaller and stronger equipment, the study still highlights the potential of a cheaper and simpler way to search for extraterrestrial life based on inducing microbial movement. The point being that cheap and simple are not two words we usually hear in association with our search for alien civilizations.
)
)
English (US) ·