Robot sub helps collect deep-ocean specimens


POSTED: Monday, June 22, 2009

As part of what has been hailed as a “;new era of ocean exploration,”; a University of Hawaii research team is back from collecting rocks and fluids from the deepest part of the ocean using a highly maneuverable robot sub that can withstand crushing pressure.

“;It has been incredibly exciting,”; said University of Hawaii-Manoa geologist Patricia Fryer, who is already working on a proposal to repeat the venture with Nereus, a unique deep-sea vehicle.

Fryer returned last week with a prized collection of rocks and sediment from the ocean's lowest point—in the Mariana Trench in the western Pacific. The so-called Challenger Deep is deeper than the height of Mount Everest above sea level.

Operated remotely from the UH research vessel Kilo Moana, Nereus dove 6.8 miles into the Mariana Trench May 31, spent more than 10 hours on the bottom, sent live video back to the ship through a fiber-optic tether and collected geological and biological examples. It also placed a marker on the ocean floor signed by those on the ship.

Dana Yoerger of Woods Hole and Louis Whitcomb of Johns Hopkins University, co-principal investigators who developed the vehicle's navigation and control system, said it dove nearly twice as deep as research submarines can go and had to withstand intense ocean pressures. Andy Bowen of Woods Hole, principal developer of Nereus, said in a National Science Foundation news release that it “;marks the start of a new era in ocean exploration.”;

Fryer, who has used different submersibles and Woods Hole's remotely operated Jason II for research on ocean plate tectonics, said Nereus “;behaved perfectly.”; She said it's naturally buoyant and easy to move around the ocean floor, which “;gives it tremendous capability.”;

Fryer, co-chief scientist of the expedition with a Woods Hole biologist Timothy Shank, said the cruise to Challenger Deep was the first time the 18-foot-long robotic submersible had been used to its full depth capability. The team included UH graduate student Samuel Hulme.

Fryer and colleagues plan to submit a follow-on proposal to the National Science Foundation for more funds to continue their studies in the trench, which forms a boundary where the Pacific plate passes like an conveyor belt beneath the Mariana plate.

Sediment and rocks were collected from the subducting and overriding plates as well as—for the first time—from deep in the crust, just above the Earth's mantle, Fryer said.

A scientific objective was to find and sample sites near the trench where fluids distilled from the subducting plate leak out, she said. Along with erupting rocks, the fluids create huge serpentine mud volcanoes on the sea floor.

Fryer wants to characterize the chemistry of the fluids at different depths, pressure and temperature.

“;We want to know how all of this relates to subduction around the globe, changes in the chemistry of the ocean in general and, therefore, potential effects those changes may have on ocean-atmosphere interactions and things like global climate change.”;

Active seafloor vents also are critically important because of communities of animals taking advantage of nutrients from springs emitting fluids, she said. “;There is close interaction between biological and geological processes.”;