Easter Microplate Expedition
April 4, 2005 Day 24
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No dive again today. It has become a cloudy, muggy day, but the real problem is that the wind is blowing too
hard. We now have just one more chance to visit this site: tomorrow. The day after that, we must be in port at Easter Island first thing the next morning. Robbie and Victor, who are the designated divers, as well as the rest of us, are in a holding pattern now, waiting for the weather to improve. This lull in the schedule gives us a chance to pull loose ends together and even pack up some things. But it is terribly disappointing to miss precious dives!
Left image: Caren and Nerida are reviewing dive tapes in the lab to finish their dive reports and to create lists of species observations. Right image: This is the station where dive tapes are copied from their original Sony DVCAM format to the format of the chief scientist's choice.
The two maps above are slope-shaded bathymetry of the ridge axis at our 26°S dive site. The red triangle marks the dive's starting point. The plan is to drive east, then turn south at the crest of the axis in the center of the map. Both maps are at the same scale: 15 kilometers, or 7.8 nautical miles, from north to south. One has very little bathymetric data in it, but that was the only data available for this part of the ridge before this morning. All night long we "mowed the lawn" for some 30 nautical miles along the ridge axis, collecting data with the multibeam sonar that is mounted to the hull of the ship. With the sea state being what it is, the ride was a bit like being on a bucking bronco. But the map that resulted is much, much better than we had before. For example, the high walls of the axial valley are barely perceptible in the old data, but are very well defined on the new map. It will give the divers a much clearer idea of where they are when they reach the bottom and can only see as far as the sub's lights can penetrate (~20m).
Today Jessica and I had a special opportunity: Greg, an Alvin pilot in training, gave us a tour of the winch/engine/Alvin rooms below the ship. The first thing we saw were boxes and boxes of materials needed to keep Alvin going or even to rebuild her if she is damaged. Greg then showed us his favorite place on the ship-the battery room (see image below). Since keeping the batteries charged and in working order is Greg's responsibility, he spends a lot of time there. While in the hanger each night, Alvin's batteries are recharged. These huge batteries are made up of 60 2-volt cells wired in series together to create 120 volts. Every couple months the batteries, each weighing 1500 lbs in water, must be removed and reconditioned. In order to be removed, they are lowered into the battery room from underneath Alvin on a hydraulic lift while Atlantis is in port. It was exciting to see the behind the scenes rooms that keep the Atlantis moving. This definitely gave us a new appreciation for the technical expertise of all the crew members who monitor this equipment and make science cruises like this possible. Whenever we have a problem, someone on the crew has a solution and all the tools needed to fix it. Its pretty amazing how much stuff is tucked away on this ship!
We watched the movie "Volcanoes of the Deep Sea" in the ship's lounge. It is about the Earth's mid-ocean ridge volcanic system and stars Alvin. It is playing now in IMAX theaters across the country. We are never short movies on the boat-check out this collection of DVDs in the ship's lounge!
All underwater photos were taken with the submersible Alvin, and are courtesy of Woods Hole Oceanographic Institution.