Neptune's Furnace

Natural History, June, 1999 by Peter Tyson

An expedition to hot springs on the ocean floor brings home samples of life at the extremes.

Dark, hot, mineral-rich water shoots through a black smoker chimney, right. Chemicals in the hot springs nourish chimney-dwelling microbes, dumps of sulfide worms and tube worms, and scavengers such as scare worms, above, and crabs.

Beginning this spring, three black smoker chimneys raised from the Pacific will be on display in the Gottesman Hall of Planet Earth at the American Museum of Natural History. The first component of the Rose Center for Earth and Space to open, the half was built with the generous support of David S. and Ruth L. Gottesman.

At 10:50 A.M. on July 5, 1998, I stood with about twenty other people on the fantail of the Canadian Coast Guard ship John P. Tilly in the northeastern Pacific, feeling the tension rise. Another ship, the Thomas G. Thompson, floated in a nimbus of mist a mile off the stern. We were about two hundred miles west of Seattle, in Canadian waters, high above the Juan de Fuca Ridge, one arm of the 46,000-mile midocean ridge system that winds around the globe. We had been at the site for seven days, attempting to harvest black smoker chimneys from the seafloor. Also known as sulfide chimneys, for their chief mineral components, they rise above the hydrothermal vents at midocean rifts, where the ocean crust is pulled apart and new planetary crust is born. These conelike structures build up when minerals, leached from magma-heated rock beneath Earth's surface, precipitate into the cold, 35 [degrees] F seawater. The name "black smoker" comes from the dark water that erupts like smoke from the hottest of these chimneys, where temperatures approach 600 [degrees] E

The previous day, a remotely operated vehicle (ROV) working at a depth of 7,200 feet, where the pressure is more than three thousand pounds per square inch, had placed a metal cage over a target chimney. A sturdy yellow 8,000-foot line connected the cage to a two-story A-frame leaning out over the Tully's stern, and then to a large green machine mounted on the deck--the U.S. Navy's Fly Away Deep Ocean Salvage System, or FADOSS, which kept the line perfectly taut even as the ship bounced on the waves.

LeRoy Olson, the engineer in charge of this operation, watched intently as the FADOSS gauge, which monitored tension on the line, climbed to fifteen thousand pounds. A winch next to the FADOSS was pulling for all it was worth. Would we pull the chimney free? Or would we be anchored to the seafloor a mile and a half down?

This expedition was the latest and boldest step in a series of investigations that began more than twenty years ago. In 1977 geologists aboard the submersible Alvin, hovering over hydrothermal vents near the Galapagos Islands, came upon a menagerie of animals never before seen--crabs, willowy anemones, bright-red shrimp, thickets of gangly tube worms. (In time, 95 percent of these vent creatures would be declared new to science.) Scientists were astonished that these animals could take the crushing pressure, extreme toxicity, and alternately frigid and scalding temperatures at hydrothermal vents. But they were even more amazed to find that in this lightless world, the microbes rely not on photosynthesis but on chemosynthesis--that is, they draw energy not from the sun but from chemicals originating within Earth itself.

Scientists saw their first black smoker chimneys in the early 1980s. Like the vents, the chimneys were draped with wildlife. But at that time, planetary scientists could only dream of having a complete sulfide structure to study close up. It took time, but the dreams became plans, and the plans led to the 1998 expedition. The American Museum of Natural History in New York agreed to sponsor the exploration of this new geological frontier and the attempt to raise several black smokers. The assembled team included scientists from the University of Washington (UW), led by marine geologist John Delaney, and researchers from the Museum, led by geologist Edmond Mathez, chairman and curator of Earth and Planetary Sciences. The first step in this quest had been taken in the summer of 1997, when a reconnaissance team aboard the vessel Atlantis created detailed maps of the site using photographic and sonar data gathered by the ROV Jason, from Woods Hole Oceanographic Institution in Massachusetts. Those maps had led the 1998 team back to the site and to specific chimneys that looked suitable for retrieval. If this expedition was fully successful, scientists would have sections of the sulfide structures and samples of their wildlife to study, and the chimneys would be displayed in the Museum's new David S. and Ruth L. Gottesman Hall of Planet Earth, which is opening in late spring of 1999.

Now, on board the Tully, scientists, engineers, teachers, and crew watched as the FADOSS gauge reached eighteen thousand pounds. Vern Miller, Olson's associate at UW's Applied Physics Laboratory, shouted over the roar of the winch: "It's just not breaking. Night now, we're attached to the whole thing." He meant the wide base of Roane--a name from Celtic mythology that UW geologist Deborah Kelley, the expedition's chief scientist aboard the Tully, had given to the chimney we were after. Over the past several years, Olson had engineered this whole effort down to the last detail. The Tully would lift the sulfide chimneys using an ROV called ROPOS, for Remotely Operated Platform for Ocean Science. Manipulated by a pilot aboard the Thompson, to which it was connected by a fiber-optic cable, ROPOS would first meticulously photograph a chimney with both video and still cameras. Then it would slip the cage over the chimney and, using its robotic hand, secure it with cables. The ROV would then use an underwater chain saw to cut partway into the chimney, just as a forester does with a tree he is about to fell. Finally ROPOS would attach the line, brought down earlier by the ROV. The line would be floated to the surface and fed into the winch, which would take up the slack and then pull until the chimney broke loose from its moorings. Three days earlier, we had used just this method to secure Phang, the first near-complete sulfide chimney ever collected. With Roane, however, Delaney had decided to forgo the chain saw and just try to yank it free, betting that natural fractures in the chimney would provide planes of weakness.