Oceanography: The Search for Thresher

The job, said the weary oceanographer, is every bit as tough as “standing in a gale and fog on top of a building a mile and a half high and trying to lower a pingpong ball on a string into a tomato can on the sidewalk.”

The job may be even tougher than that. Nonetheless, the U.S. Navy is determined to locate the sunken nuclear submarine Thresher, 8,000 ft. down on the cold, dark bottom of the North Atlantic. No wreck has ever been found or even seriously searched for at so great a depth. But for weeks a strange fleet of floating scientific laboratories has been cruising the choppy waters 220 miles east of Cape Cod, and this week the weirdest craft of all is being towed into range. The bathyscaphe Trieste is preparing to dive toward the spot that undersea snapshots have tentatively marked as Thresher’s grave.

It is a suspicious “bump” on the bottom known as Contact Delta. Judged by its size and shape, Delta may well be Thresher’s hull, crushed and mangled by water pressure. But getting a good look so that scientists on the surface can make sure has proved to be an elusive problem.

The Beast. Weeks ago, Atlantis II, of the Woods Hole Oceanographic Institution, lowered “The Beast,” a weird M.I.T.-designed rig. At the end of the Beast’s 9,000-ft. cable, a small echo sounder measured its distance from the bottom. A pair of powerful strobe lights flashed at six-second intervals, and two cameras took pictures. In the eternal darkness at 8,000 ft., they needed no shutters; they merely advanced their film in time for the next flash from the strobes.

It was beastly work. Off Cape Cod, the Atlantic is a battleground for the warm Gulf Stream and the cold Labrador Current, and the weather veers from dim to foul. Strong subsurface currents swirl at unknown depths below. But the crew of Atlantis was both skilled and lucky; photos taken a half-mile north of Contact Delta showed a string of debris on the bottom. The pictures picked out hundreds of pieces of twisted metal, a shredded copper cable, a half-pint milk carton standing peacefully right side up, and a white Navy coffee mug lying on its side. Nothing has yet been identified conclusively as coming from Thresher, but everything is clean and new-looking, and the metal is untarnished.

As soon as the first debris was photographed, all search ships zeroed in on Contact Delta. The research ship Robert D. Conrad, of Columbia University’s Lament Geological Observatory, dredged up 15 envelopes of gaskets, and the Atlantis found two broken pieces of battery plates. Both gaskets and plates are almost certain to have come from the lost sub. Latest pictures from Conrad show an air bottle of a type used on Thresher and a broken piece of pipe* that was probably once a part of the sub’s internal plumbing.

Trieste on Call. The Navy is reasonably sure by now that Thresher lies close by, under a small area of ocean marked by bright orange buoys. Hopefully, the Trieste will soon photograph the actual wreck. The depth will be moderate for the Trieste, which has already cruised to the bottom of the Marianas Trench off Guam, 35,800 ft. down, but the strong currents off Cape Cod are a serious threat. Though proof against water pressure in the deepest ocean, Trieste has feeble propulsion. She can creep only four or five miles at about 1.4 m.p.h.; during the 45 minutes that it will take Trieste Skipper Lieut. Commander Donald L. Keach to guide his strange craft to the bottom, unexpected currents may carry her out of sight of the sunken submarine.

If Thresher eludes both Trieste and the oceanographers’ instruments, the Navy has one more ace up its gold-braided sleeve. It has worked out a scheme for scuttling the decommissioned submarine Toro near the place where Thresher sank. As Toro settles through the water followed by sonar beams, she will tell how the currents affect a sinking submarine. Her crushed hulk lying on the bottom, its position pinpointed, will tell the dogged Navy, as it continues its search, what Thresher should look like to oceanographic instruments.

*Just such a break, concluded a Navy Court of Inquiry last week, probably sank the sub by flooding the engine room with sea water.