NOAA Ship Ron Brown-Teacher Logbook July 30, 2001

Teacher Logbook - NOAA Ship Ron Brown

Don't lose your head around here, shrunken heads experiment underway.

image of ROPOS crew, click for full size

The ROPOS crew and Chief Scientist Bob Embley, before the last dive of NeMO 2001. (l-r: front seated-Bob Holland, Bob Embley; second row-Ian Murdock, Craig Elders, Keith Sheperd, Keith Tamburri; third row-Sebastian Duran, Kim Wallace.)

Jeff Goodrich's Sealog:
Axial Volcano - ASHES Vent Field
July 30, 2001

Patience is a virtue. The winds have dropped, the swells have lessened and ROPOS is back in the water for it's last dive of the NeMO 2002 cruise, which will be at ASHES vent field. In the NeMO tradition I'm conducting my own deep-sea experiment. I've sent down a colored Styrofoam head attached to the cage. Pressure at the Earth's surface is around one atmosphere (14.6 pounds per square inch). As my head descends, it will be subjected to one more atmosphere of pressure for every 10 meters it drops. By the time it reaches Axial Volcano around 1500 meters depth, it will experience 150 atmospheres of pressure (about 2200 pounds per square inch). My Styrofoam head should come up at about a quarter of its original volume. Talk about a headache. I'll have the Tylenol ready. Check out the picture of a head that's already returned from the deep. Chemist Susan Lang and a full-sized Styrofoam head are used for scale. Notice how well Susan mimics the expression of a shrunk head.

Fish, crabs, octopus, worms, limpets, snails, clams, and all the other fauna living near the vents at Axial must be able to stand the intense pressure depth. In contrast, surface fish that contain air-filled swim bladders could never withstand the pressure exerted on the deep-sea fauna. Their swimbladder would collapse and kill the fish. Besides heat and corrosion from the vents, the pressure at the bottom is important when deploying instruments. The big yellow floats used to raise anchored moorings to the surface contain 3/4 inch thick glass that's rated to 6000 meters (9000 psi). ROPOS is encased in a shell made of glass micro-balloons in an epoxy matrix. It's extremely durable at depth and able to provide needed buoyancy. If the vehicle were not built to withstand the pressure it would come up looking something like Susan Lang's shrunken head. Definitely not large enough to hold all the samples we hope to recover on our final dive at Axial.