Thousands of feet below the surface of the Earth is salty water that hasn’t seen the light of day in millions or even billions of years. Miners working deep underground had encountered and wondered about the origin of this water for decades, but it wasn’t until the 1980s that scientists started to investigate where this water was coming from and what it might contain – giving researchers clues into how life survives in the deepest parts of our planet.

In this episode, Barbara Sherwood Lollar, a professor of earth sciences at the University of Toronto, describes the process of going deep underground to find and research the origin of this old water, including the discovery of the oldest water on Earth. Barbara also describes how research into the origin of water on our planet and the life potentially contained in these fluids helps scientists understand where life might lurk on other planets, like Mars.