2023-04-25 20:00:00
Read this story in English here.
In August 2019, Chloe Fishman went into a cave under the largest active volcano on the planet. Along with scientists from NASA and other institutions, she had gone to Hawaii’s Mauna Loa volcano to study the microscopic life forms that could survive below, in the dark and isolated subterranean environment known as a “lava tunnel.”
Fishman descended 30 feet (9 meters) through an opening in the ground formed where part of the tunnel had collapsed. He wore a headlamp on his helmet, as well as gloves and knee pads. As he moved deeper into the darkness, Fishman felt the temperature drop. The moisture in the air swallowed her up. As his feet touched the cave floor, Fishman began to look around him: “I felt like I had entered a different world,” he said.
It might as well have been on Mars. And that was precisely why Fishman and his colleagues had come to Hawaii.
“The microbes we found in Hawaii could be similar to microbes that once lived on Mars, or even microbes that live there today,” said Fishman, who, at the time of this study, was a university researcher at the laboratory of Sarah Stewart Johnson, a tenured professor at Georgetown University in Washington DC Fishman is now a researcher at the Gladstone Institutes at the University of California, San Francisco.
Microbes thrived in Mauna Loa’s lava tunnel, Fishman and his colleagues found, even in areas that did not receive sunlight, which most living things on Earth need to survive. In these dark areas, the microbes were probably using chemicals from the rocks for their food.
In August 2019, scientists from NASA and other institutions explored a lava tunnel in Hawaii’s Mauna Loa volcano. In this image, they walk through piles of rock debris that form when lava cools rapidly. These rocks contain glass that sticks to your pants, like sharp Velcro.
Credits: NASA Goddard
Fishman and his colleagues discovered dozens of previously unidentified microbe species. They also collected information about their habitats that will inform strategies to one day collect samples in Martian lava tunnels, the researchers reported on February 17, 2023, at the Journal of Geophysical Research: Planets. Mars is one of NASA’s top destinations for looking for signs of ancient or present microorganisms, with several missions underway or in development.
The lava tunnel that Fishman and his colleagues studied, located on the north flank of the volcano, formed about 200 years ago, classifying it as a “young” tunnel on the geologic time scale of billions of years. Less Affected than older tunnels by water and other weather conditions, a young Hawaiian tunnel more closely resembles Martian lava tunnels as they were billions of years ago.
When lava tunnels first formed on Mars, the red planet was likely similar to Earth, with active volcanoes, an atmosphere, a warmer climate, and flowing waters. Since these conditions helped nurture life on Earth, they may have done the same on Mars. Even though the Martian surface became inhospitable to living things after the planet lost its atmosphere, cooled and dried out about 3 billion years ago, microbes could have migrated underground, scientists suspect.
Inside the Hawaiian lava tunnel, lit by headlamps, the walls had a luminous mural in yellow, orange, pink, green and white. These materials contained a variety of minerals, including gypsum and calcite, arranged in shapes that reminded Fishman of mushrooms and popcorn. Although Fishman had gone to the cave to scrape samples back to the lab to look for microbial life, most of his colleagues had come there to study the minerals. Work on the minerals is ongoing, but it will intersect with Fishman’s if some of these minerals turn out to be more likely to harbor microbes than others. Information from this investigation could help Martian rovers identify promising sites to sample for signs of past or present life.
Scientists descend into a lava tunnel on Mauna Loa, Hawaii, to study the microbes and minerals within.
Credits: NASA Goddard / Molly Wasser
“At the Martian surface and just below it, we have identified minerals similar to those found on Mauna Loa,” said Amy McAdam, a geochemist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. McAdam is a member of the science team for NASA’s Curiosity rover, which explores Mars and also analyzes samples taken from the surface in its onboard chemical laboratory.
“Even if it is difficult to discover signs of life in Martian minerals, we can still learn a lot from them about the environmental conditions of the origins of Mars and whether or not those conditions were favorable for life,” McAdam said.
After a week of work in the lava tunnel, Fishman brought about 20 half-teaspoon-sized samples to Johnson’s lab. He poured each sample into a test tube filled with liquid and glass beads the size of grains of sand. A device in the lab stirred them to separate the components of the samples, thereby releasing the cells into the liquid. This allowed Fishman to extract DNA from the cells. DNA sequencing revealed the genetic codes of organisms.
Fishman has sequenced the genomes of 72 new organisms. So far, he has analyzed the genomes of two microbes, allowing him to classify them based on their characteristics and add them to global databases.
Por Lonnie Shekhtman
NASA Goddard Space Flight Center, Greenbelt, Maryland
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