The excitement of the Lost City vent field had clearly galvanized expedition members. But the hectic pace of nightly Argo-II runs, coupled with morning-to-late-evening rock processing and Argo photo mosaicking, were also wearing down the science party.
So there were mixed feelings when the Argo run for the night of Tuesday, Dec. 5 was cancelled due to the same high seas that had unexpectedly boiled up earlier in the day during Kelley's and Karson's memorable vent dive.
Late Fall storms off the United States' east coast were beginning to influence the mid-Atlantic as far south as these north Florida latitudes, reminders that this cruise would soon be over.
Fig. 1. Weather satellite image across the North Atlantic, December 13, 2000, image at http://psbsgi1.nesdis.noaa.gov:8080/PSB/IMAGES/ comp_gifs/nhdir.gif
The seas were gentler on Thursday, Dec. 7, as John and Morgan descended in the research submarine Alvin to a site at the top of the south wall where she had earlier hoped to find signs of a detachment fault.
At the 3:15 p.m. science meeting that followed, John reported finding north-south trending faults, massive cliffs, and more deposits of the kind of sedimentary carbonates that had attracted attention at other sites. There was also lots of coral at the top, along with shrimp, and what Alvin pilot W. Bruce Strictrott described as "red crabs with multicolored legs."
That night Argo paid a final visit to the west flank of the massif. But that survey ended at 2 a.m. to allow time for its 3,000 meter wire to be cleaned and reeled in one final time - at least for this expedition.
Meanwhile, Atlantis' crew, with help from the science party, was spending spare moments recovering more of the 12 navigational transponders that had been dropped around the mountain when the ship first reached the study site back on Nov. 15.
That recovery work actually began on Wednesday Nov. 29 and continued in stages thereafter whenever the expedition switched its focus from one part of the massif to another - negating further need for special navigation other than the ship's own satellite assisted system.
Fig. 2. Transponder recovery in blustery weather. Suzanne Lyons and Nick Bacher watch Atlantis crew member Raul Martinez snaring the yellow transponder with a grappling pole.
As it took more than an hour for them to reach the bottom, it took similar time for the buoyant transponders to bob back up. Their ascents began after specially coded sonar signals commanded them to activate high voltage currents that disintegrated wires holding them to anchoring weights.
Separate sonar signals kept Atlantis' crew informed of the transponders' general whereabouts. But it still took lots of spotters - some on the main deck and others perched up on the ship's bridge - to locate the small yellow objects in a very big ocean.
That was especially true on Nov. 29, a no-launch "weather day" for Alvin, when sharp eyes and the deft use of long grappling hooks managed to snag three transponders in pitching water.
Friday, Dec. 8, the final day of operations, dawned perfectly beautiful. Alvin was launched with Cann aboard, who began a complex mission to make gravity measurements and visual observations along the mysterious corrugated part of the massif's top.
The dive plan called for the second-to-last transponder to be released mid-dive, after Cann and the pilot located a gravity station that had been established during an earlier Alvin trip.
At the science meeting that followed, Cann, of the University of Leeds, reported that he successfully "reoccupied" that station, using it as a benchmark for establishing four more additional ones. "Disappointingly, I saw no outcrops," he said.
Cann did note the "very intriguing carbonate crusts" covering portions of the surface there too. "The only way we're going to find out what the carbonates are is by going and drilling," he added. Scientists have submitted a proposal to return to the site with a drilling ship.
"Most interesting was the biota," he added. "There were all sorts of green things that looked like sponges." Bobby Lee (Blee) Williams, Cann's pilot, added: "That was the only green thing I've ever seen at the bottom of the ocean."
The search for the final transponder brought a large number of the science party to the the starboard side of Atlantis's aft deck, where researchers lingered and talked in the warm late afternoon sunlight. The mood was broken well before the last transponder was spotted and returned to Atlantis' deck at 5:10 p.m.
By 5:30, Atlantis was speeding northwest, bound towards Woods Hole at a speed of 12 1/2 knots. This would be the ship's first return to home port in more than three years, and its crew was losing no time. "We're done, thank you all," Blackman told the science team. Actually the researchers were far from done. They returned to work, finishing up late dive reports, packing up equipment, and continuing the painstaking work of analyzing some very strange rocks.
Wrapping up | Where we stand | A new kind of hydrothermal vent | One thing leads to the next