Friday, February 18, 2005

We began Jason II surveying in our second study area. Among the rocks collected by Jason II was our first suite of gabbros (rocks that form the lower half of the oceanic crust). One of the most challenging aspects of designing equipment to use on the bottom of the ocean is to account for the enormous pressures at these great depths (2-3 miles deep). In Alvin, the scientists and pilot occupy a titanium sphere that is designed to withstand these pressures. However, on the outside of Alvin, the pressure is the ambient pressure of the ocean floor at that depth. One of the things that we do for amusement is to take styrofoam coffee cups or mannequin heads, decorate them with permanent marker, and then place them in a net bag that remains on the outside of Alvin. The great pressure at the ocean floor shrinks these styrofoam objects (see shrunken coffee cups next to a normal-sized cup; see Dave Naar’s before-and-after pictures of the mannequin head.)