The HPIES experiment about to be dropped to the seafloor from the surface. It is kept balanced by a series of weights attached to the bottom, so the equipment doesn't tip over on its way down.
The deployment of the HPIES (Horizontal Electrometer Pressure Inverted Echosounder) instrument off the fantail of the Thompson at the Axial Base site. The instrument was designed to freefall to the seafloor from the surface, and did so successfully.
Photo Credit: Ed McNichol, Mumbian Enterprises, Ltd.
The Horizontal Electrometer-Pressure-Inverted Echosounder (HPIES) is an instrument that utilizes a bottom pressure sensor, a 12-kHz inverted echosounder and a horizontal electrometer to measure the horizontal electrical field, the bottom pressure, and the vertical acoustic travel time from the sea floor to the sea surface. These properties provide insights into the vertical structure of current fields and water properties including temperature, salinity, and specific volume anomaly, separation of sea surface height variation and temperature, and near-bottom water currents.