While methane gas is not a major component of the Earth’s atmosphere today, billions of years ago it helped to keep our planet from freezing when our sun was not as bright. Today our sun is much brighter. If we add more methane to the atmosphere, its ability to trap heat can contribute to making the planet even warmer than it is now.

My work onboard Expedition 337 includes looking deep sea microorganisms that are able to eat methane before it can escape to the atmosphere. Microorganisms have many special adaptations to be able to live deep down where there is no light, no oxygen, and very limited nutrients. For example, the ones I study make the work easier by sharing the load between two different forms of life: Archaea and Bacteria. Archaea and Bacteria are as different from each other as we are from them - and they are just single cells!

Anaerobic glove box in microbiology lab on the Chikyu.
No oxygen in here, which is more preferential condition for deep life than the air.

We know that they have evolved a way to make a living off methane by working together, but exactly how they do it is still a great mystery. I will be collecting samples on this cruise where methane consuming, or methanotrophic, microorganisms are most likely to exist in the sediment cores we bring onboard.

I will take the samples back to my research lab and keep them sort of like pets. I will give them the temperatures, foods, and nutrients I think they will like to see if I can find microbes that will eat methane. I will do this by adding a special kind of methane that I can track. If this special methane is eaten, I will see it stored in parts of the cell when I put them under the beam of a machine that gently strips away atoms and tells me what kind are there (called a NanoSIMS). These samples come from low energy environments, so even with partner microbes, they still grow very, very slowly. This means I will have to wait many months to years before I know if my experiments worked.

Studying how microorganisms are able to use methane in an environment with no oxygen and little nutrients also matters to scientists looking for life beyond our planet, Earth. While onboard I have been following the progress of the Mars rover Curiosity that just successfully landed. Many of my friends and coworkers at my home institution, Caltech, are involved in this mission and were very happy to see it landed safely and begin sending data back to Earth. One of the main missions for this rover is to look for possible signs that life could have existed (or does exist!) on Mars. Our work to study the limits of life in the deep subsurface of the Earth is helpful for understanding what may be possible on other planets. I am very excited to see what we will find and look forward to sharing the results of our special mission.

Enjoying a beautiful sunrise before lunch on the night shift.