Interview with Hanumant Singh - Part 2
by Lonny Lippsett, photo by Chris Linder
Would you describe the vehicles you will be using on the Gakkel Ridge expedition?
We will have four different kinds. The first thing we’ll probably do when we get to a potential vent site is deploy a CTD. A CTD is lowered on a cable and towed behind by a ship. CTD stands for “Conductivity, Temperature, and Depth,” and making those measurements will help us locate plumes. In this case, our CTD will also be equipped with sensors to detect particles and chemical clues, which both indicate the presence of a hydrothermal plume. The CTD will give us a rough idea of where the plume is.
What happens if the CTD finds a plume?
Then we send down our autonomous underwater vehicles. These are basically robots that have no tether or anything connecting them to the ship. They are preprogrammed onboard the ship to do missions on their own. So they are called autonomous underwater vehicles, or AUVs.
We have two vehicles in this class that we have designed and built. One is called Puma, which stands for Plume Mapper. It’s a vehicle designed to search for hydrothermal vent plumes. It has sensors that detect particles, temperature, and chemicals, which can tell us not only that a vent is present but also how close we are to the vent that is producing the plume. Puma can help us narrow down the area where the hydrothermal vent “smokestack” may be from area of a few kilometers to a few hundred meters.
Then what?
We can then eventually move in with the second vehicle, called Jaguar, which stands for “Just Another Grand Underwater Autonomous Research” vehicle. Jaguar is designed to use sonar to make high-resolution maps of the vent fields and cameras and lights to photograph them.
Our AUVs are designed to work like helicopters and hover very close to the bottom. The kinds of terrains that we expect to find are very harsh, rugged, and steep. If we could walk on those terrains, we would need rock-climbing gear. We couldn’t just scramble up them. And so Jaguar needs to figure out what the terrain is like. Yet it also has to be close enough to it—within a couple of meters—so it can take good images. And it also has to stay out of trouble—you know, stay away from the caves, not hit a cliff, and it has to do that autonomously.
What’s the fourth vehicle?
Once Puma and Jaguar work in concert to locate a vent site and map it, then we will move to our last vehicle, which we call Camper—a combination of “Camera and Sampler.” It is towed on a cable by the ship, a little bit like a toy on a string.
Can’t the ice floes snap the cable?
We will have to deal with the fact that ice floes tend to coagulate behind the ship, and those ice chunks can interact and cause harm to the cable. So we’ll physically have to keep an eye on ice pieces as they migrate around the tether and try to make sure that the tether is in an area that is free of ice.
What is Camper’s mission?
Camper has thrusters that should allow it to hover above a vent site for a short time. It has lights and cameras to photograph the site. And, most importantly, it has sampling mechanisms to bring back animals and rocks from the hydrothermal vents. The biological samples are very important, because biologists are really interested in extracting DNA from the samples so that they can understand something about the evolution of life by looking at these organisms.
What’s the sampling apparatus like?
We really don’t know what we’re going to find down there. We don’t know whether we’ll find organisms that are moving, such as shrimp, or clams or tubeworms, which are stationary. For moving organisms, we made a sampler that sucks samples into a container. For stationary organisms and rocks, we wanted something like a clam bucket or scoop.
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