FeMO4 Dive Cruise 2009
Report Day 14 -- Wednesday 14 October 2009 -- Giant Bobbers!!
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FeMO4 Dive Cruise 2009 |
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Early the next morning I look out my cabin window and see a gigantic yellow bobber being hauled on board. I think to myself -- That must be one enormous fish! Then I remember I’m on a scientific research vessel, not a fishing boat. I look again and see the Jason crew pursuing another giant bobber off in the distant waves. My curiosity is stronger than my desire to sleep. I have to go down and investigate. In all, three bobbers are captured, dragged onto the stern of the ship, and stowed in a cage with a bunch of other huge bobbers. Once the mission has been accomplished, I ask Bob (one of the Jason crew), “What’s up with the big bobbers?” Bob tells me that each bobber is actually a transponder and is part of the Long Baseline (LBL) navigation. He says that at the beginning of the expedition, three transponders were placed in a triangle around Lo’ihi. It takes 3-4 hours for the Kilo Moana to exactly locate each transponder by using sound waves. Then, Medea uses the same process to place itself exactly with respect to these transponders.
It sounds like an amazing system, but what prevents the transponders from floating away? Bob tells me that the transponder is attached to a wire cable and weights that sit on the ocean floor – 3,000 feet down – and act as an anchor and the transponders are floating a couple of hundred feet above that. When the Jason crew is ready to retrieve the transponders they detach the cable from the transponder. Then the cable curls itself around the weights on the ocean floor.
Bob tells me LBL is actually old technology and that Woods Hole has recently purchased a new navigational system called Ultra Short Baseline (USBL) navigation. It works similarly except the transponders are attached to the corners of the ship and therefore the transponder cable and weights aren’t left on the ocean floor at the end of the expedition. The environmentalist in me thinks that is an excellent improvement. He tells me that we are pulling in the transponders because we have completed our last Jason dive at Lo’ihi.
Since we are leaving Lo’ihi I wonder where we are headed for the upcoming days. In the computer lab I see Hubert and Tito planning out the next dives. Hubert is the chief scientist on this cruise and one of the principal investigator of the National Science Foundation grant that sponsors the FeMO expeditions. He is a renowned volcanologist from Scripps Institution of Oceanography at University of California, San Diego. Tito is the lead of the Jason crew from Woods Hole Oceanographic Institution in Woods Hole, Massachusetts and also one of Jason’s original builders. They tell me that we are on our way to South Point of the big island of Hawaii to conduct three dives on another small volcano.
After the dive is planned, Hubert begins to plot out the trip home to Honolulu. He uses a chart of the Hawaiian Islands and three oceanographer tools, a ten-point divider, rulers, a compass, and a triangle. He is charting our route home so we can pass by other seamounts on the way. He plans to have the Kilo Moana map out some pieces of ocean floor that have not been mapped with a high resolution sonar.
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