Deploying the elevator
June 15, 2013
Day two was calm enough for a few operations. This morning we deployed the benthic elevator outfitted with respirometry chambers, and a new sediment trap funnel that we’re pressure-testing. Once the elevator was placed overboard and released, it took about two hours to sink to the bottom. Even though it weighs almost 1,300 pounds in air, it needs additional dense weight in order to sink in seawater. The marine operations team adds 150 pounds, just enough to help it sink slowly so as not to crash land. Stay tuned for tomorrow’s plan to see what goes into the respirometry chambers.
After we deployed the elevator we recovered the mooring. At the base of the mooring is a camera tripod, above which are two sediment traps. Floats keep these instruments held upright underwater once they land on the seafloor, but also, once we send the instrument an acoustic signal to drop its weights at the end of the mission, the floats help it rise slowly to the surface. These floats must be able to withstand sinking down thousands of meters under water, and remain buoyant down where pressure is over 315 times that at the surface (use this website to calculate how much pressure there is at various depths http://www.calctool.org/CALC/other/games/depth_press). These floats are made out of syntactic foam, a material that can handle the pressures of the deep sea, remain buoyant at all of their working depths, and are very heavy at the surface.