Lava tubes aren’t just dramatic natural structures here on Earth—they could be the key to discovering alien life. A new study suggests that these deep volcanic tunnels, already considered ideal shelters for future astronauts, might also be the best place to look for biosignatures on Mars.
Inspired by places like the vast tunnels beneath Lanzarote in Spain’s Canary Islands, scientists are rethinking where and how we might uncover signs of life beneath the Red Planet’s surface.
How lava tunnels form—and why they matter
Lava tubes form during volcanic eruptions when the surface of a lava flow hardens while the molten rock underneath keeps flowing. Once the eruption ends, the lava drains away, leaving behind long, cavernous tubes—some so massive they’ve been turned into concert venues.
But this recent expedition into Lanzarote’s tunnels wasn’t for music. Researchers entered these ancient formations to study their mineral makeup—and to look for life. What they found, published in Communications Earth & Environment, could reshape how we search for life on Mars.
Sulfate deposits in the La Corona lava tube, Lanzarote, Spain. © Bogdan Onac
Hidden life—and signs of the past
The team discovered that these tunnels offer a stable environment perfect for preserving both minerals and microbial activity. They found colonies of bacteria thriving inside, as well as calcium and sodium sulfates—clues that microbial life had been present for quite some time.
These are precisely the types of biosignatures scientists hope to one day detect on Mars.
A researcher takes samples from one of Lanzarote’s lava tubes. The white spots on the walls represent microbial colonies. © Bogdan Onac
“Our study helps us understand Earth’s geological evolution and shows that lava tubes could be safe havens for microbial organisms,” explains Bogdan Onac, geosciences professor at the University of South Florida. “This has major implications for astrobiology and future missions aimed at finding signs of life on Mars and other worlds.”
What makes lava tubes so promising? On Mars, they offer something the surface can’t: protection. These tunnels provide natural insulation from extreme temperatures and shield life from deadly cosmic radiation—a serious threat on a planet with little to no atmosphere.
Even more promising: Martian lava tubes likely contain minerals rich in sulfates, which some bacteria use as a food source. That makes them not just protective—but potentially habitable.
Lava tube opening at the summit of the Martian volcano Pavonis Mons. © NASA, Jet Propulsion Laboratory, University of Arizona, Wikimedia Commons, public domain
A new path for future missions
It’s highly likely that Martian lava tubes closely resemble those found on Earth—especially in terms of mineral composition, including sulfate-rich materials that certain bacteria rely on to survive. Even more important, these subsurface tunnels provide a remarkably stable environment, shielding whatever lies within from the planet’s extreme surface temperatures and relentless solar radiation.
Because Mars lacks a protective atmosphere, harmful radiation easily reaches the surface, making it extremely difficult for organic matter to survive up there. But below ground, the story could be very different.
This contrast is crucial—and it could fundamentally reshape where and how we search for life on Mars. The findings of this new study strongly suggest that future missions should shift their focus from the surface down into these ancient lava tunnels, where life may have once existed… or still might.
Morgane Gillard
Journalist
As a child, I dreamed of being a paleontologist, an astronaut, or a writer… and ultimately, my heart led me to geology. After years of studying to gain deep knowledge, I now share it with you, the readers of Futura!
Looking back, I realize that my passion for Earth and science in general started very early! My first spelunking expedition was at the age of 4, my first scuba dive at 7, fossil hunting all across France, nighttime outings to watch the stars… With a father who was a chemistry teacher and an avid cave diver, and a mother who was the first female commercial diver in France, my childhood was filled with adventure and discovery! One memory in particular stands out: observing the Hale-Bopp comet in 1997, in the middle of the night, standing in a field while my parents whispered the countdowns for the exposure times to photograph that strange celestial object lighting up the sky. That image is forever etched in my memory, a moment filled with a certain magic—and even today, I still get chills when I gaze up at the stars. Head in the stars, feet on the ground. It was probably during our travels in an old Volkswagen van, between Andalusia and the barren lands of the North Cape, that I discovered the incredible beauty of nature and the stunning diversity of landscapes our planet has to offer.
Discovering Earth and Its Inner Workings
After high school, pursuing scientific studies felt like a natural choice, so it came as no surprise when I enrolled at university for a full degree in Earth Sciences. But I struggled to stick to just one field. During my studies, I explored all areas of geoscience: from geodesy to electromagnetism, from mineralogy to field geology… I loved learning about Earth and its complexity, its beauty, its strength, and its fragility. So when I was offered the chance to start a PhD in geodynamics in 2011—studying the development of the Australian and Antarctic margins—I didn’t hesitate. More things to learn and discover!
One of the most fascinating aspects of geosciences is how you juggle both vast timescales and spatial scales. You never stay still—you’re constantly zooming in and out. In a single day, you might shift from looking at the oceanic crust to analyzing a tiny mineral. You might be discussing tectonic plate movements and then chemical interactions between minerals. What could be more exciting?
From Continent to Ocean: The Incredible Journey of a PhD
Over those three years, I gradually specialized in seismic interpretation. Like a detective, I learned to read those striped black-and-white images and reconstruct a story—the story of plate tectonics and the opening of an ocean. Specifically, I worked on the development of detachment faults in the continent-ocean transition zone and the sedimentary record they produce. I had the opportunity to present my work at many international conferences and built a strong scientific identity. Three years of hard work, amazing discoveries, and incredible encounters shaped me into who I am today. After defending my thesis in 2014, I completed several years of postdoctoral research with CNRS and in collaboration with oil companies interested in these increasingly strategic zones for petroleum exploration.
Science, Always and Forever
But… academia is demanding, requiring full-time commitment—something not always compatible with starting a family. So I made the tough decision to shift career paths and turned to scientific writing. It turned out to be a great choice, as it allows me to keep talking about science, especially geology. Working with Futura is a real opportunity because it lets me share the world of Earth Sciences—an often-overlooked field—with a broad audience. After all, what could be more important than understanding the planet we live on?
