Hess Deep Home














Expedition Dispatches


Dispatch No. 8


Tuesday, March 30, 1999 22:27:20 GMT
From Monte Basgall, Duke University Senior Science Writer
Location: 2 degrees, 21' N; 101 degrees, 25' W
Weather:

  • Wind: 10-12 knots
  • Seas: 8-12 feet
  • Skies: partly cloudy
  • Air temperature: 82 degrees Fahrenheit
  • Seawater temperature: 86 degrees Fahrenheit

  • By the evening of Saturday, March 27, Hess Deep expedition scientists and students were beginning to get punchy.

    The earlier day had been tropical picture perfect. It was captive to becalming equatorial doldrums that so diminished wave action that the Pacific looked surreally viscous - less like ocean than a round patchwork of lazily bobbing blue gelatin.

    When Alvin's distinct orange conning tower and encircling Avon disturbed that placid surface just before 5 p.m., the sudden rippling glinted like pearls in the sunlight. The dripping research submarine was quickly returned to the deck of the R/V Atlantis carrying 19 pieces of rock from about two miles below, as well as two diving researchers: Bob Varga of The College of Wooster in Ohio and Jay Miller of Texas A&M.

    This dive had run into continuing problems with the geocompass, just like the previous two. One thruster also stopped working, and a cockpit digital hand held camera never did. After a quick supper, a bucket brigade of Hess Deep team members reassembled on deck to unload all the precious samples from Alvin to a nearby "wet lab." Then it was time for a science meeting, followed by more work that would continue around the clock.

    The daily science meetings, now relocated from Atlantis's library to its main laboratory, provide the one daily opportunity to assess how all the parts of this complex geological exercise are unfolding.

    Each meeting begins with a quick report of the last dive. In this one, Miller and Varga described how Alvin landed in an area of dikes. Then, as the bright glare of the submarine's lights penetrated the gloom, the pair had furiously logged and photographed their upward passage through places where the dikes were cut by lava flows, then on up further into the lava sections themselves.

    The transition was similar to what Varga had previously seen in Cyprus while studying dry land ophiolites, uplifted sections of former oceanic crust, he would recall later

    They had also managed to collect nine "oriented" samples before the geocompass's electronics again went haywire. That means rocks whose angles of tilt, and their positions relative to the magnetic north pole, were determined on site by the geocompass and its internal computer.

    Jeff Karson, a Duke University professor who is chief scientist for the Hess Deep mission, first made such measurements on a 1990 Alvin dive to the same area after having had the magnetic geocompass custom built for him by the Woods Hole Oceanographic Institution.

    By knowing a rock's precise present orientation, scientists can then back-calculate how it has been "rotated" by geological forces since it formed, a major interest of the Hess Deep study.

    Researchers learn this by conducting separate "paleomagnetic" studies, which draw on the fact that Earth's magnetic field is frozen into the rocks as they solidify.

    Scientists have evidence of past magnetic orientations, and can thus compare the "then" with the "now."

    Varga, an expert in using paleomagnetism to study rock structure, also praised the Argo II photographic surveys for helping him, Miller and Alvin pilot Matt Heintz find their way along Hess Deep's tortured terrain. "I was amazed at how well prepared I felt," he told the scientists and students gathered around a chart-covered table. "I was amazed when I saw outcroppings in places where I thought I should see them, and how really representative the Argo images were."

    While the Argo missions had been interrupted for crew shift rotations before the Alvin dives started on Thursday, March 25, they had resumed by 6 p.m. that very afternoon. Under a new, abbreviated schedule, Argo II would be sent down each night and retrieved early the following morning, in time to launch Alvin again.

    That meant more long nights for the Hess Deep team members who monitored video screens and navigational fixes in the Argo II control van.

    On the very first restructured Argo midnight watch, shift leader Gail Christeson, a University of Texas at Austin seismologist, had reported finding an "incredible outcrop" that included cross cutting dikes pointed in "every orientation," she said, some dipping east and others west, some at angles as low as 30 degrees.

    An explanation for such an increased variety of angles might be extruding lava piling up on the dikes, she would add later.

    After the March 27 science meeting adjourned, the Hess deep team quickly scattered. Some walked through a series of hatches to the control van to begin the evening's Argo shift. Others slid into chairs before several different kinds of terminals in Atlantis's computer lab.

    Dan Curewitz, a Duke doctoral student specializing in structural geology, sat in front of one glowing screen plotting maps for the next day's Alvin dive. Using an automated program he spent six months researching before Hess Deep's start, Curewitz punched in latitude and longitude. He also entered navigational fixes provided by some of the transponders that had been placed at the study's beginning along the rim above the Hess Deep wall.

    Another input was "bathymetry" (depth) information from Atlantis's "Seabeam" sonar array, which constantly bounces signals between the ship's undersides and the ocean bottom. But Curewitz had to carefully put those data in perspective.

    "Bathymetry can only be a rough guide," he said. "It usually has at least 30 meters (99 feet) worth of error. Sometimes it is really good, and sometimes it is 150 meters off."

    After he had finished on the keyboard, Curewitz's graphical software took all that information and plotted out detailed dive charts. "I can get it to print out any piece of a map, at any scale I want," he said.

    On the other side of the computer lab, images from Miller's and Varga's hours-ago dive were already playing on a bank of video monitors. Amazingly sharp, the digital recordings from two miles down showed pilot Heintz's painstaking efforts to use a crowbar and the sub's grasping robotic arms to pry loose a rock sample outside the vessel.

    A few minutes later, the video camera was now panning over an outcrop as striking as it was difficult to interpret. Then there was a flash of recognition, as the researchers focussed on two familiar hooded eye-like indentations in the rock. "It's Spiderman," Karson shouted.

    Meanwhile, back over in the main laboratory, Duke senior Aisha Morris was busily checking which scientists had turned in what from previous Alvin dives. Karson had assigned her the role of being the Alvin "czarina," responsible for making sure dive reports were finished promptly and completely.

    These painstaking reports include transcripts of voice tape recordings, video tapes from Alvin's digital cameras, data logs from the geocompass, freehand sketches of individual rock samples as seen through Alvin's windows, and sketches of the numbers, shapes and locations of samples placed in collection baskets.

    "I'm supposed to remind people," Morris smiled wryly. "Here I am, a little undergraduate, telling these professors to Get your stuff in!'"

    Another of her duties is to take "strip maps" - running sketches Alvin divers made of the terrain they visited - and plot them onto a large master chart of Hess Deep Argo II and Alvin activities.

    At a nearby main table, Duke doctoral student Michael Stewart used a hand lens to study the granular details of rock sample slices as part of his large scale studies of the origins and movement of magma along mid ocean ridges. He also continued a running debate with the constantly circulating Karson on whether certain rock samples are "basaltic" or "mafic."

    If that wasn't enough, Stewart was attempting to "reconstruct" unrecorded time and navigational information from the Alvin dive he and Karson made on Thursday, March 25, vital input that was missing because Alvin's on-board data logger had malfunctioned.

    Among the tools he was working with was a special electronic interface that could affix missing "time stamps," frame by frame readouts of the time a recording was made, to videotapes of their dive.

    Soon Morris moved over and began squinting through a hand lens herself at one Stewart's samples. "He said this one is a gabbro, and this one is not," she said. "I'm trying to figure it out." She is currently taking a Duke course in petrology, the science of rocks, but is missing some lectures, not to mention spring break, to go on the Hess Deep research cruise.

    Then all work halted as the key last minutes of the mens' basketball tournament game between Duke and Michigan State played themselves out over Armed Forces Radio. Because the ship was pointed in the worst direction for reception, it was hard to tell cheering from static. But Karson and Morris had no trouble catching the magic words that Duke had won.

    Suddenly both were jumping in the air by the table where the ship's own ping pong tournament playoffs continued. "Big Ten gets whooped today," Morris screamed, as both exchanged High Fives. Despite such bursts of occasional spontaneity, the Hess Deep expedition has been carefully planned, Karson said days later.

    We set up things so they could run by themselves," he added. And because the operations began one at a time, with Argo II following the DSL 120 side scan sonar, and Alvin beginning after that, "everyone knows exactly what to do."

    "Things are very highly structured and everybody has got something to do all the time," he continued. "People have two days to write up their reports after each dive. And if they do not get their dive reports done, there is no chance that they will dive again."



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