The latest advance in the search for extraterrestrial life could come from the “wiggles” of swimming microbes—microscopic single-celled organisms that are abundant in just about every nook and cranny of Earth.
Microbes are found throughout our planet’s biosphere because many of them are able to flourish under very harsh conditions that apparently preclude larger, more complex life-forms. And that remarkable resilience is why astrobiologists are so keen to study them. If, for instance, microbes can thrive in a lake buried beneath Earth’s south polar ice cap, maybe similar organisms could exist in glancingly similar extraterrestrial environments, such as the mysterious ice-covered ocean of Jupiter’s moon Europa or water-logged regions of Mars’s subsurface. But the trick isn’t to merely show that alien life might exist in such places but rather to confirm that it does—which requires detecting its presence in the first place. Most interplanetary life-detection experiments have involved looking for chemical tracers—biosignatures—that otherworldly microbes might create in their environments as a by-product of their metabolism. Now, however, a new approach based on microbes’ self-guided movement, or motility, may be in reach.
Historically, testing for microbial motility has been an expensive and time-consuming task, ill-suited for incorporation into robotic space missions. That’s prompted a team of German astrobiologists to devise a simpler, more cost-efficient way to check for motility, an approach that they have detailed in a study published on February 6 in the journal Frontiers in Astronomy and Space Sciences.
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