Clues to "alien life" found in Earth's deep seas

Scientists are searching for clues about what kind of life might exist in the depths of space by studying alien-like creatures living in the Earth's deep seas.

Scientists believe that the most likely form of extraterrestrial life would be microscopic organisms. Even within our Solar System, there are some planets and moons that could host such life.

These studies may answer humanity's age-old question: Are we alone in the universe?

ONE OF THE MOST POSSIBLE ADDRESSES IS EUROPA

One of the strongest candidates for extraterrestrial life is Jupiter's fourth-largest moon, Europa, which is covered in a thick layer of ice.

However, astronomers believe that saltwater oceans may exist beneath this ice sheet. NASA observations suggest that Europa's ice crust could be 15 to 25 kilometers thick, while the underlying liquid ocean could reach depths of 150 kilometers.

Another factor that could make Europa habitable would be if the moon had a hot, molten core that provided heat and essential minerals to the ocean floor.

"Based on our own planet, we think Europa might have conditions that could support life," says microbiologist James Holden of the University of Massachusetts Amherst in the US, in an interview with Evrim Yazgın of Cosmos magazine.

OCEAN EXPLORATION EXPEDITION

Holden is leading an expedition not to the depths of space, but to the deep ocean floor, a region of Earth that has yet to be fully explored. He believes that hydrothermal vents thousands of meters deep under the seafloor are an ideal place to understand what life might be like on other worlds.

“I’ve been studying deep-sea volcanoes since 1988,” Holden said, explaining that to collect microbes from these vents, they descend about a kilometer and a half below the ocean surface, sometimes with manned and sometimes robotic submarines, and bring the samples back to his laboratory.

NASA has allocated approximately $1 million to Holden's team for a three-year project. This research will guide scientists on how to track possible life on Europa and what signs to look for.

"Conditions on Europa may be similar to those experienced by hydrothermal microbes on Earth. So if life exists on Europa, it will likely have organisms similar to our hydrothermal microbes," Holden says.

"We've long been intrigued by the possibility of life beyond our planet and how it functions. Perhaps the answer lies within our own planet; that's very exciting."

LIFE IN HYDROTHERMAL CHIMNEYS

On Earth, deep-sea microbes produce energy by splitting hydrogen released from hydrothermal vents, using enzymes called hydrogenases. Different types of hydrogenases perform different functions in different cells.

Holden's team will study deep-sea microbes on Earth to understand how microbes could survive in a world with a different chemical makeup.

“We need to figure out what chemical processes microbes on Europa might use to produce energy,” Holden said, noting that different chemical environments could lead to very different microbes.

NASA's Europa Clipper spacecraft , launched in October 2024, will provide new observations of Jupiter's moon during its five-year mission. This data, combined with Holden's Earth-based research, could provide concrete evidence of whether life truly exists on Europa.