Washington, D.C. 19 June 2009 |
Prior to the test run of a new robotic vehicle last month, underwater research vehicles operated no deeper than 6,000 meters. Nereus changed that.
The newly developed hybrid ROV Nereus is launched from the RV Kilo Moana during a test cruise in 2007 off Hawaii |
"Nereus is a tool which we hope the scientific community will use to make important discoveries about that final 4,000 meters of the ocean," he says.
Bowen says the hybrid design allows Nereus to be operated remotely while tethered to its mother ship or to run as a free-swimming craft controlled by onboard computers.
Nereus's specialized manipulator arm samples sediment from the deepest part of the world's ocean - the Mariana Trench |
Using these maps, scientists onboard the surface ship direct Nereus in its tethered mode through a fiber-optic cable. Bowen explains this lighter cable replaces the steel reinforced copper wire cables used by traditional robotic systems.
"We are able then to go in with a mechanical arm and high-quality cameras and actually interact directly with the sea floor under human control."
Because the 40-kilometer-long tether is so light - it weighs less than a kilogram and is nearly as thin as a human hair - it does not snap under its own weight and can withstand the crushing pressure of the deep ocean. The cable uncoils from both ends - a canister onboard the robot and one attached to the surface vessel.
WHOI biologist Tim Shank (at right) and Patty Fryer (left), a geologist with the University of Hawaii, examine the samples retrieved from the Mariana Trench |
Nereus weighs 3 tons and is just over 4 meters long and 2 meters wide. It is powered by 4,000 lithium batteries. The craft carries ballast weights in its descent to 11,000 meters, diving at 20 to 30 meters a minute for eight hours. The weights, Bowen says, are dropped on the sea floor.
"It really neither sinks or floats and using its propulsion system, which is a series of small propellers, we can actually drive the vehicle around near the sea floor much in the same way you might think of a helicopter. And that driving is done by a pilot 7 miles [11 kilometers] away on the surface vessel through a joystick."
The Challenger Deep in the Mariana Trench is located near the island of Guam in the west Pacific. It is the deepest abyss on Earth at 11,000 meters |
"Certainly, the role, for example, of the trench in the carbon cycle; how carbon is recycled within the [earth's] crust. Things such as earthquakes, various other chemical processes are an important part of coloring in a picture about the ocean that is critically important to our understanding of the global environment."
During its 10-hour dive to Challenger Deep, Nereus sent back high-quality video, gathered rocks and samples of deep ocean sediments and returned with microbes and small worms that live in extreme depths. But, Bowen says, Nereus has barely scratched the surface of the ocean floor, and he expects a research team to mount an expedition with Nereus within a year.
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