Name: Jill McDermott
Title: Ph.D. candidate, Woods Hole Oceanographic Institution
Location: Woods Hole, Mass.

Where will you be sailing?
We’ll sail onboard the research vessel Atlantis to the Mid-Cayman Spreading Center, which harbors the world’s deepest chain of volcanoes. It’s south of the Cay­man Islands and west of Jamaica and Cuba. We first visited the site two years ago with a submarine called Nereus, and we found evidence of three new hydro­thermal vents. On this cruise, we want to send our remotely operated underwater vehicle [ROV] Jason down to do a sam­­p­ling mission at one of those vents and at another one discovered in 2010 by a team led by the U.K.’s National Oceanography Center, Southampton.

Tell me more about the area you’ll be exploring.
The Mid-Cayman Spreading Center is a really exciting place to work, partly because of the diversity of the environ­ment there. It’s an ultraslow-spreading ridge, which means it has a low level of volcanic activity and a lot of tectonic activity. There are many different types of rocks, from volcanic basalt to peri­do­tite, a rock that’s more like the mantle and gets pulled up from deeper within the earth. The rock composition around a vent is a big driver of that vent’s chem­istry, and what I hope to understand is the chemistry of these two systems and how the pressure and rocks can cause the chemistry to change.

How do you find a hydrothermal vent?
We use a sensor that looks for the reducing potential of the water—how much oxygen is present. A deep-sea hydrothermal vent emits water that contains very low levels of oxygen. That low-oxygen water comes up from the vent, and as it drifts along we can detect the plume.

Once you find a vent, what do you need to do to sample it?
We’re sending Jason on the sampling mission with four titanium bottles that will hold water samples; other people are sending bioboxes and things to put sulfide structures in. Jason is a workhorse. It’s a really powerful sub­marine. It can stay down for more than 24 hours and has strong manip­ulator arms.

What else are you hoping to find?
Our studies seek to extend the known limits of life on earth. One of our goals is to understand whether or not organic molecules can be synthesized abiotically [without living organisms] in deep-sea hydrothermal vents, which carries im­plications for the origin and suste­nance of life on the early earth and will inform future missions searching for life on other planetary bodies.

This article was published in print as "Probing the Depths."