No back-seat driving, please.
June 2, 2002
by Lonny Lippsett

“OK, let’s see what the hound found,” said Dana Yoerger. He was up in Atlantis’ Top Lab, about 35 feet above deck, where Alvin Pilot Bruce Strickrott was tracking the submersible’s movements 1,660 m below the ocean surface. Overnight, ABE, the Autonomous Benthic Explorer, had scouted out a section of the seafloor and sniffed out a small area with possibly warm ocean-bottom waters—a sign of active hydrothermal venting. Alvin headed toward the spot.

Bruce and Dana stared at the sonar that marked Alvin’s position. The room was mostly silent, except for the occasional “clicks” of the echoing sonar.

“He’s heading east,” Dana said, and waited. Several minutes passed. “He’s slowed down,” he said. More minutes passed in silence. “Say something,” Dana said.

But you don’t chat with Alvin Pilots at work on the seafloor. In fact, you do not talk with them at all unless it is truly important. Driving Alvin—in the dark, on a jumbled volcanic seafloor, in strong currents such as today’s—requires complete focus. Distractions are strongly discouraged. No matter how tempting it is, back-seat driving from Atlantis is definitely NOT welcome. No one on deck can know all the things the Pilots may be dealing with on the seafloor.

“We’re basing our decisions on what we can actually see out the viewports—things people on the surface cannot see,” said today’s Pilot, BLee Williams. “And the scientists also have a mission and a train of thought that should not be broken.”

While some of us paced on deck, Alvin was following a seafloor fissure several feet wide. The sub came upon a large field of dead worms, called serpulids, and heaps of dead mussel shells.

And then two brown spires rose from the seafloor—1 m and 2 m high. Clusters of dead mussel shells fanned out from the base of the spires. They were vent chimneys, but they were extinct. Here, for the first time, was evidence of high-temperature hydrothermal venting on the Galápagos Rift. Since vents were first discovered 25 years ago here, the highest temperature venting ever recorded on the Galápagos Rift was just the other day at the “Rosebud” vent site—22.5°C (72.5°F).

BLee sampled a piece of the extinct chimney and brought it up. It was speckled with shiny crystals of metal sulfides. These only form when vent fluid temperatures reach 200°C (392°F), Susan Humphris said.

“We have one last dive,” Tim said this evening. ABE, the CTD, and our deep-sea camera will spend the night searching for more leads of active venting. If they find something, we will search for an active black-smoker chimney gushing particle-laden fluids into the ocean. If they don’t, we will return to the lush new vent site we discovered yesterday.

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