Interview with Rob Reves-Sohn - Part 1
by Lonny Lippsett, photo by Chris Linder

Rob Reves-SohnA bath inspired you to explore the Arctic? You’re making that up, right?
I know, it doesn’t sound like it should be a true story. But one day about 10 years ago, I was giving my new daughter, who was a couple of months old, a bath and trying to make sure she’s entertained while simultaneously cleaning her. We had all this white soapy foam and all these toys in the bathtub. We had a Sesame Street submarine that Elmo was the captain of, that went under the foam. And somehow the thought just kind of clicked: “That’s what we need—robot submarines that can go under the ice to explore the Arctic Ocean.”

At the time, I was naïve. I didn’t realize that people had been developing robotic underwater vehicles for many years. I had no idea they even existed. And then, eventually I ended up at Woods Hole Oceanographic Institution, which has several robotic underwater vehicle labs. So, I definitely ended up in the right place.

Why have you targeted the Gakkel Ridge for your mission below the Arctic Ocean?
Well, in 2001 a research cruise went to the Gakkel Ridge to dredge rocks from the seafloor. The ridge is 3 or 4 miles under water, so to get those rocks you use a long wire and basically lower a huge bucket with teeth and chains and drag it on the bottom. Just to collect as much data as possible, the scientists on the cruise also put sensors on the wire to measure the temperature and clarity of the ocean water on the way down.

In the deep ocean, the water is cold and clear. But on mid-ocean ridges, where Earth’s tectonic plates are spreading apart, you can get a lot of heat and volcanism. Seawater seeps through cracks in the seafloor, gets heated up, and rises and vents out of the seafloor. You get plumes of slightly warmer, cloudy water that spread out like smoke from a smokestack.

To everyone’s complete surprise on the 2001 cruise, almost every single time they lowered the wire down into the water, they found evidence for hydrothermal plumes. And this was really stunning. Nobody really knew quite what to make of it.

Why was that so surprising?
Because the theory was that mid-ocean ridges are kind of like car engines: The faster they go, the hotter they get, and the more water you need to cool the system.

So, when you have two tectonic plates that are moving apart very rapidly, like for example in the Pacific, that’s like a Ferrari. It’s a well-lubricated, smooth-running machine. You get a lot of heat, a lot of volcanism, and a lot of seawater percolating through cracks in the seafloor.

The Gakkel Ridge, on the other hand, is like the Chitty Chitty Bang Bang of mid-ocean ridges. It’s spreading apart ultraslowly. The whole process doesn’t run smoothly. It’s herky-jerky. You don’t have much heat or volcanic activity, so you ought not to have hydrothermal venting, or not much. And yet all the sensor evidence from the 2001 cruise screamed, “Holy cow! It looks like there’s hydrothermal plumes all over the Gakkel Ridge!” And that’s pretty exciting.

Exciting how?
For a lot of reasons. But one of the first is that there’s a lot of anticipation—if we can find these vents—about what kinds of animals are going to be living there. We have no idea.


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