Editor’s Note: Veteran science journalist Philip Hilts is working with a team of archeologists, engineers and divers off the shore of Antikythera, a remote Greek island, where a treasure ship by the same name sank in 70 B.C. New, high-tech gear is allowing the team for the first time to examine and excavate a wreck with the care and thoroughness of an archeological dig. This is the third installment in a series, the entirety of which can be found by clicking here; or follow these links to the first and second stories (a table of contents can also be found at the end of this post).
Antikythera, Greece—After two weeks of delays due to nasty winds, the high-tech diving outfit called the Exosuit finally splashed into the sea on Tuesday, October 7 above the site of a 2,000-year-old shipwreck near Antikythera Island, Greece. (Scientific American published an article about the suit in March.)
The boots of the suit broke the waves of the Aegean Sea at 10:40 in the morning, and with several scuba divers hovering like cleaner fish, sank to about 200 feet, just adjacent to the wreck site.
It was the suit’s first mission, “the first time in salt water,” said Jim Clark of the J. F. White Contracting Company of Massachusetts, owner of the suit. The diver inside the glistening, muscle-bound shell was Edward O’Brien of the Woods Hole Oceanographic Institution. On a second dive yesterday, Chief Petty Officer First Class Fotis Lazarou of the Greek Navy piloted the suit.
The suit was designed to be the next step in scuba diving for underwater work, including in this case, archeology—a huge step giving the humans inside a far greater ability to withstand high, underwater pressure and to stay submerged for long periods.
After coming out of the water yesterday, O’Brien said the experience was completely unlike scuba diving. “You don’t have any sense of pressure or depth. Fifty feet feels the same as 200 feet, except maybe it’s darker at 200.” He said the cloak is more like a little submarine with bendy arms and legs.
The first site for the suit is among the most famous in the history of underwater archeology: a ship that sank in about 70 B.C., carrying literally tons of treasure—dozens of marble and bronze statues as well as gold jewelry and coins. The most famous part of its treasure was a precision bronze clockwork device now called the Antikythera Mechanism, the first known analog computer that tracked the movements of the sun, moon and planets, and was able to predict eclipses.
The Exosuit, designed and built by Nuytco Research Limited, was to be deployed for several dives to some of the deeper spots on the wreck site. But the fierce north winds in the past two weeks forced cancellation of some of the dives.
Yesterday, however, the suit accomplished an important part of its first campaign—testing whether it could be successfully deployed here. The Hellenic Navy ship “Thetis” had to moor close to the rock wall where the treasure ship sank, then swing O’Brien and the suit over the water on a winch. The winch first raised Exoman O’Brien about six feet off the deck of the ship, swung him slowly out over the side, and lowered him slowly into the water. The winch cable was then detached, and O’Brien and the suit sank down to the level of the wreck. In wind and waves, the task was not trivial.
On land, the suit weighs more than 500 pounds, but it is light as a feather in the water, almost neutrally buoyant. It is made of metal and is designed to keep a diver at an air pressure the same as the surface while diving down to 1,000 feet. On future dives the suit will have a specially designed accessory, a suction hose that will allow the suit and its inhabitant to remain on the bottom for many hours, drawing up sand and silt from the wreck to get at the precious objects believed still to be on the site.
The suit has a tether that carries an optical cable and a wire cable for communications and to send back images from its video camera. But the breathing aboard comes not from surface air, but from a scuba “rebreather” on the suit’s back that contains a tank of oxygen and a “scrubber” that removes carbon dioxide from the diver’s exhalations.
Although air contains about 21 percent oxygen, each time a person breathes he or she uses only a portion of that, leaving about 16 percent still available. After scrubbing out carbon dioxide, the rebreather adds some oxygen from the tank to top up the air for the diver. The suit has two emergency backup tanks, but with its regular setup it can last for up to 50 hours underwater.
The key to the suit’s usefulness is it’s multiple joints—there are 18 of them—that allow divers to move their hands and arms naturally so they will be able to do delicate work on the bottom. To permit the diver to move around on the site, the suit has four small propeller “thrusters.” By moving his feet up and down, left and right, the diver can move to any position horizontally or vertically.
George Bass of Texas A&M University, who is called the “father of underwater archeology” because he has used scuba diving to excavate underwater wrecks since 1960, said in a recent email that the suit holds great promise for the field. That is primarily because, he said, it will allow a diver to stay at depth and work for many hours at a time, compared to the few minutes per dive that used to be available for excavations on the bottom.
Jim Clark of White Contractors said he hoped that this year’s experience will lead to long excavations on the site in the future. “This suit is perfect for it,” he said.
Images courtesy of ARGO.
Other posts in this series:
"Marine Archaeology Goes High-Tech"