A test bed in the search for life

In 2021, The Planetary Society launched a new program to fund innovative science and technology projects: STEP (Science and Technology Empowered by the Public) Grants. STEP Grants are competitively awarded through an open international process every two years. Winning projects relate to the Society’s core interests of exploring other worlds, finding life, and defending Earth from dangerous asteroids.

One project that was awarded a STEP Grant in May 2023 involves studying super-salty lakes on Earth as analogs for environments we think likely exist on other worlds like Mars, Europa, and Enceladus. 

Led by Jacob Buffo, PhD, of Dartmouth College, the project has been conducting field studies in a group of hypersaline lakes in British Columbia, Canada. Two of these studies took place in the late summer, when these lakes are drier than usual and therefore saltier — “what we believe concentrated ephemeral lakes on Mars could have looked like,” says Buffo. Ancient Mars was a warm, wet planet, and as it became colder and lost its surface water, it’s possible that hypersaline lakes were the last to dry up. If so, these could have provided “the last hypersaline refuges for any potential organisms,” according to Buffo.

The other two expeditions revisited these same sites in the dead of winter, when the lakes were frozen over and icy layers formed. These environments could be similar to those on moons like Europa and Enceladus that are thought to hide oceans of salty liquid water under their ice crusts. If life exists anywhere else in the Solar System today, it could well be on moons like this, making the hypersaline lakes great targets in analog studies of habitability. 

So far, the team has collected more than 400 unique samples of lake ice, salt, brine, and sediment. These samples are being analyzed for microbial life, organic content, and ecological structure to better understand how the physics, chemistry, and biology of these extreme environments interact. 

A major goal of the research is to pinpoint where the richest microhabitats exist within these extreme lake systems. Another goal is to identify the kinds of biosignatures that we might be able to spot when we visit those places. Essentially, the research is helping us better understand where and how to look for signs of life on other worlds.

One result Buffo’s team has found so far is that hyperspectral drone imagery has been useful in mapping key features like brine pools and mineral ridges in lakes like this. This might support the use of flying spacecraft like NASA’s Ingenuity or Dragonfly helicopters to scope out where to search more thoroughly for signs of life.

By testing out techniques, tools, and theories here on Earth, Buffo and his research team are helping make sure that when we go out to search for life on other worlds, we’re as prepared as we can be.

Learn more

Information about our STEP Grant program can be found at planetary.org/sci-tech/step-grants.