This week a USC scientist who spent 65 days at sea in search of life hidden beneath the seafloor returns from a successful expedition, which she chronicled in regular blog posts from her ship.

Katrina Edwards of USC Dornsife and Wolfgang Bach of Bremen University co-led a team of more that 100 scientists and support crew that drilled four cores through the sediment of the Atlantic Ocean’s seafloor and into the bedrock below, filling them with instruments and then sealing the holes shut.

“The success of this program was simply tremendous,” said Edwards, professor of biological sciences, earth sciences and environmental studies. “We faced great challenges and hurdles over the past two months, and in the end enjoyed significant achievement for scientific advancement.”

From the safety of dry land, the public was able to follow along with Edwards on the hazardous trip by reading her blog, which was published on the Scientific American website at blogs.scientificamerican.com/expeditions/ and on the Center for Dark Energy Biosphere Investigations (C-DEBI) website at darkenergybiosphere.org/return-to-northpond/

The instruments Edwards and her team placed will gather hard data about the microbes that live at the bottom of the biosphere - the portion of the Earth that is inhabited by living organisms. Edwards and other scientists from C-DEBI will return next year to harvest the data.

Drilling cores 400 meters below the ocean’s surface and remotely placing sterile scientific instruments without introducing any contamination required marathon workdays aboard the ship, the JOIDES Resolution.

“A challenging aspect of this type of work is the relentless pace,” Edwards said. “When installing sub-seafloor laboratories like we were, your day begins and ends only when the installation begins and ends - these are 24- to 36-hour operations. There are no breaks.”

About one-third of the world’s biomass is thought to exist below the ocean floor and has seen little scientific study to date. Edwards’ expedition is part of a multiyear effort to explore this untapped world. She plans to continue collecting data at the North Pond over the next five years.

Edwards' goal is to learn more about the role that tiny subseafloor microbes play in shaping the oceans and crust of the Earth. Current evidence suggests that, despite their size, they could be a major factor shaping massive oceanic features. At this point, however, scientists need more raw data to know just how major.

For now, Edwards and Bach have plenty of unpacking, cleaning and report-writing to keep them busy. Edwards is expected to return to teaching classes in the spring semester.

The expedition was funded by the Integrated Ocean Drilling Program, and C-DEBI is supported by the National Science Foundation.