Brown professor to co-lead international research on subsurface environments

The biosphere that exists below Earth’s surface dwarfs the surface biome, and a new collaboration co-led by Jack Mustard will work to better understand what’s underground.

PROVIDENCE, R.I. [Brown University] — Brown University professor Jack Mustard has been tapped by a premier Canadian research institute to co-lead an international collaboration aimed at understanding underground environments on Earth and throughout the solar system.

Professor Jack Mustard
Jack Mustard

The project, called Earth 4D: Subsurface Science and Exploration, will be supported by CIFAR, a nonprofit that encourages long-term, interdisciplinary study of big questions in science and society. Earth 4D is one of 13 programs selected for CIFAR’s research portfolio, following a worldwide call for proposals.

“In recent years there’s been a recognition that Earth’s deep biosphere is absolutely enormous, larger in terms of biomass than the surface environment,” said Mustard, a professor in Brown’s Department of Earth, Environmental and Planetary Sciences. “But as it stands now, our understanding of the subsurface comes from largely isolated points — deep mines or faults — spread sparsely around the world. What we’re trying to do is figure out a way to connect that information into a more robust, three-dimensional view of the planet.”

And by developing a better understanding of how these environments interact and change over time, the team hopes to add a fourth dimension to that view (hence Earth 4D). The ultimate goal, the researchers say, is to better understand the factors that sustain subsurface environments and habitats while shedding new light on water resources, energy resources and the planet’s carbon cycle. 

Mustard will co-lead the project with Barbara Sherwood Lollar of the University of Toronto. The two have assembled a team of about a dozen researchers around the world, each with expertise in various aspects of the problem. Sherwood Lollar is a highly decorated geologist who has done pioneering work in understanding crustal fluids and the geochemistry that sustains subsurface life. Mustard’s work is largely in planetary science, including the exploration of potentially habitable environments on Mars and elsewhere.

Mustard says the lessons learned from research on Earth’s underground could be useful in looking for subsurface life (or the remains of past life) on Mars or perhaps the moons of Jupiter and Saturn.

In a recent collaboration, Mustard and Sherwood Lollar showed that ancient Mars very likely had the right geochemical environment for a thriving subsurface biome. Understanding more about Earth’s subsurface biome could help scientists plot an exploration strategy to look for signs of ancient Martian life. At the same time, the Martian subsurface could teach us about our own subsurface world. Unlike on Earth, ancient crustal environments on Mars haven’t been ground away by plate tectonics. So Mars could provide a present-day snapshot of Earth’s ancient subsurface, helping us understand the evolution of life on our own planet.

The researchers say that the big-picture nature of their project is perfect for CIFAR’s approach to science, which encourages its researchers to assemble teams from diverse backgrounds and fields of study.

“I think CIFAR is going to be particularly catalytic for us,” Sherwood Lollar said. “The program will enable us to bring together people from extremely different perspectives, and then give them the intellectual freedom to challenge each other, challenge themselves and change thinking.”