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Digging Deep Volume 59 Number 3, May/June 2006
by Marianne Alfsen

Revolutionary technology takes archaeologists to new depths.

[image] A remotely operated vehicle (ROV) is hauled aboard after a day of excavation in the icy depths off the Norwegian coast. (Fredrik Naumann) [LARGER IMAGE]

A tiny crawfish popped out of a 300-year-old ceramic jar and stared in disbelief at the creature threatening to evict him from his home. At 560 feet down on the muddy bottom of the Norwegian Sea, visitors from the surface are rare--even more so when it's a hulking, brightly lighted robot reaching a hydraulic arm toward you.

High above the jar, in the control room of a research ship, the technician running the remotely operated vehicle (ROV) watched a camera screen as he steered the robot's arm around the jar, nimbly avoiding the field of fragile wine bottles and Asian ceramics that lay half-buried in the mud around it. The thick tether connecting the ROV to the control room transmitted a response from the robot's hydraulic "fingers," essentially enabling the operator to "feel" the object as he watched himself pick it up through the "eyes" of the remote camera. As the jar was carefully deposited in a basket for delivery to the surface, the now homeless crawfish hurriedly swam away.

Originally developed more than half a century ago by the U.S. Navy to locate weapons and ships lost in depths beyond the reach of scuba divers, increasingly more sophisticated ROVs are now commonly used by world navies and natural-resource industries for deep-water exploration and construction. The first glimpse of robots' enormous potential in marine archaeology came in 1989, when a team led by Robert Ballard and Anna Marguerite McCann used an ROV to successfully investigate and sample a late Roman wreck more than 2,000 feet deep near Skerki Bank, off the coast of Sicily. Since then, engineers and archaeologists have endeavored to advance from mere visual survey and random removal of artifacts with ROVs, to full-blown robotic excavations.

There were two major problems to solve in excavating underwater sites with ROVs. First the robots, which generally operate independently underwater, attached only by a tether to the command vessel, are bulky and weigh hundreds or thousands of pounds; there is a risk that they may disturb or even destroy the very sites they are sent to investigate. Second, accurate and delicate maneuvering of an ROV (which relies on powerful thrusters to maintain a steady position) on an archaeological site has been a challenge. "This is why most deep-sea archaeological operations have been limited to documentation, sampling, and digging trial trenches," explains Marek E. Jasinski of the Norwegian University of Science and Technology in Trondheim, pointing to recent ROV surveys in the Black Sea and the eastern Mediterranean by Ballard's Institute for Exploration, and an ongoing survey in Greece by MIT and the Woods Hole Oceanographic Institute.

"All groups working on deep-sea excavation arrived at the same conclusion--that the best way forward was an ROV attached to a frame," says Brendan Foley of Woods Hole. While a frame set over an archaeological site would prevent the robot from accidentally coming into contact with fragile artifacts, and allow archaeologists to maneuver the ROV with more precision, the cost of developing and testing the new technology was prohibitive for academic researchers.

But then, in 2003, Jasinski and his colleague, Fredrik Soreide, had a magnificent stroke of luck.

Marianne Alfsen is a Norwegian-based freelance journalist.

© 2006 by the Archaeological Institute of America