The Hunt for Red Hot Hydrothermal Vents
Hot, mineral-rich fluids gush from hydrothermal vents on the seafloor. To search for vents and the animals that live around them, scientists floating atop the ice-choked Arctic Ocean first look for plumes of fluids that trail out from the vents and drift in the depths. (Illustration by E. Paul Oberlander, WHOI)
STEP 1: ?TOW-YO-ING' FOR PLUMES?For oceanographers, the thermometer and smoke detector hanging down is called a CTD, which measures conductivity (salinity) and temperature at various depths. This tried-and-true instrument is scientists? first tool to look for hydrothermal plumes. The CTD is lowered all the way to the bottom and pulled up again while it is also towed by the ship, which researchers call a ?tow-yo.? CTD sensors detect slightly warmer temperatures, mineral particles, and certain chemicals?all telltale signs that the CTD has passed through a plume. ?It?s hit or miss,? said University of Texas marine geochemist Hedy Edmonds, who headed CTD operations on the expedition.
Still, with a little luck and a lot of experience, over many CTD casts, scientists constructed a map of water over the seafloor, showing areas (yellow and red) with suspected plume fluids.
WHOI physical oceanographer Peter Winsor peers over the massive bow of the icebreaker Oden as an instrument called a ?CTD? is dangled into the ice-covered Arctic Ocean depths. Arching behind his head is a fogbow, a common Arctic meteorological phenomenon caused by sunlight refracting water droplets in a fog bank.
STEP 2: UNLEASH THE ROBOTIC 'CATS'?WHOI engineers built three new vehicles to search for hydrothermal vents beneath the Arctic Ocean. The first two are sleek, torpedo-shaped, free-swimming robots called Puma and Jaguar. Once the CTD provides a rough idea of where a plume is, Puma is deployed through a hole in the ice and programmed to conduct missions on its own, said WHOI engineer Hanu Singh (left, with MIT/WHOI graduate student Clay Kunz, right). Equipped with sonar and sensors to ?sniff out? telltale temperature, chemical, or particle signals of hydrothermal plumes, it is designed to help scientists track the plume to its vent source.
Jaguar is deployed next, using sonar to create seafloor maps (above) and to home in on vents, hovering above them while its camera and lighting systems collect images of the vents and any animals living around them.
STEP 3: A DEEP-SEA CAMPER?The third new under-ice vehicle, designed and built by WHOI engineers led by John Bailey, is called Camper (short for ?camera/sampler?). Above, WHOI engineer John Kemp guides Camper into an ice-free pool created by the icebreaker Oden. The 6,200-pound steel-frame box?5 feet wide, 7 feet long, and 5.5 feet tall?is towed behind the icebreaker, which drifts with the ice pack. Camper is lowered to the seafloor via a winch and a fiber-optic cable.
Camper is equipped with camera and light systems to send real-time images, such as this deep-sea octopus, back to scientists aboard ship.
Researchers can send commands to the vehicle?s thrusters to maneuver and hover Camper briefly over vent sites and to operate its samplers: a ?grabber? to snatch hard samples such as clams or rocks (above) and a ?slurp gun? to vacuum in samples of fluids or microbes.