That’s a current hope:
In places like South Africa and Canada, work in terrestrial deep mines — which descend into rocks that are billions of years older than the oldest seafloor basalts — has hinted at this for the past decade. Sherwood Lollar, along with Princeton University’s Tullis Onstott and other colleagues, have ventured into those mines to study what they call “the hidden hydro-geosphere,” systems of water isolated deep underground on long geological time scales. In some cases, they’ve found water that hasn’t been exposed to surface environmental factors in millions or even billions of years.
And in that billion-year-old water, the researchers have found life.
They’ve also found evidence that those microbes persist by getting energy from an abiotic process called radiolysis, during which radiation released by the rocks reacts with water in the system to release hydrogen, which the cells can then use in various forms as fuel. That’s posed an intriguing question for scientists: Could radiolysis be an alternative process driving much of subsurface life? …
D’Hondt agreed. “From a literally universal perspective, it opens up the potential for sustaining life on all kinds of planets,” he said. “There could be life on other worlds that’s independent of photosynthesis,” thriving beneath the surface, out of sight.Jordana Cepelewicz, “Inside Deep Undersea Rocks, Life Thrives Without the Sun” at Quanta
Funny how we always have to make it about finding life on other planets, as if this stuff weren’t fascinating enough. Maybe it’s a funding thing…
See also: The Science Fictions series at your fingertips – origin of life What we do and don’t know about the origin of life.