How deep is Earth’s habitable region?

Scientists from the University of Rhode Island’s Graduate School of Oceanography will try to answer that question during an international research expedition off the coast of Japan.

Arthur Spivack, a professor of oceanography, and graduate students Justine Sauvage, of Belgium, and Kira Homola of Washington state, are among the 31 researchers from eight countries participating in the project.

They’ll depart from Shimizu Port in Shizuoka, Japan Sept. 12 aboard the D/V Chikyu, the largest scientific research vessel in the world. Working with shore-based scientists, the team will drill deep into the ocean floor off Japan to determine the maximum temperature that can support life. The Earth gets hotter at deeper depths.

“It’s exciting to participate in such a big project, especially as I approach graduation,” says Sauvage, who is getting her doctorate in oceanography, with a focus on chemistry and life in sediment. “I’m using the technology I learned at GSO and applying it in the search for deep life.”

Sauvage has a special interest in how microbes use hydrogen as their food source. The 28-year-old Brussels native played a key role in solving the mystery of the beach explosion at Salty Brine Beach last summer, which was caused by hydrogen. In the international drilling expedition, she’ll apply the same methods she used at the beach: high precision measurement of low levels of hydrogen gas.

Spivack says Sauvage is one of a handful of people in the world who can conduct this kind of research. Her dissertation examines how naturally occurring radioactivity in the ocean leads to the production of hydrogen gas.

Sauvage has been on numerous research cruises—including an expedition to the North Atlantic in 2014—but this is the first trip where she is working in a senior position.

“This trip is a culmination of my research over the years, particularly in the role of hydrogen as a food in the deep biosphere,” she says. “I’m grateful to participate in the expedition and thrilled I was selected for this competitive opportunity.”

Homola, a native of Whidbey Island in Puget Sound, also helped solve the Salty Brine explosion. Her expertise is in interpreting the chemistry of the waters in the ocean crust, which she uses to understand the ocean’s role in controlling climate. She is a third year doctoral student at GSO.

On the expedition, Homola will work alongside Sauvage and Spivack as an inorganic geochemist measuring the different chemical properties of water extracted from sediment.

“This expedition is a truly incredible opportunity for me,” she says. “I’m looking forward to working with top-notch scientists from all over the world to better understand this unique environment.”

The scientists will conduct their research at Nankai Trough, 75 miles off the southeastern coast of Japan where the sea is 3 miles deep. The team will drill a mile into the ocean floor to collect samples that will be examined on the ship and at laboratories throughout the world. The ship will return to Japan Nov. 12.

The International Ocean Discovery Program, an international marine research collaboration that explores Earth’s history, dynamics and deeply buried biology through studies of seafloor sediment and rock; the Japan Agency for Marine-Earth Science of Technology; and the Center for Marine Environmental Sciences at the University of Bremen in Germany are sponsoring the project.

Sauvage is a member of the Deep Carbon Observatory, a 10-year initiative to intensify global attention and scientific effort in the burgeoning field of deep carbon science. Several GSO faculty are also members, and the science outreach portion of the Deep Carbon Observatory is orchestrated by GSO.

Sauvage is expected to blog on the expedition for the Deep Carbon Observatory at

Spivack is making his second trip to the spot. Fifteen years ago, he went on a drilling expedition to investigate earthquakes in the area.

“It’s very exciting to use this opportunity to train GSO graduate students in an international project that is on the cutting edge of science,” says Spivack. “We’re trying to understand the limits of life on Earth and the implications for the possibility of life on other planets. We feel privileged to be involved in this rare opportunity.”