Sentry, a new autonomous underwater vehicle (AUV) built by engineers at Woods Hole Oceanographic Institution (WHOI), completed its first scientific mission last summer, scouting out sites for an undersea observatory network off the coast of Washington state. Sentry is the successor to ABE, the Autonomous Benthic Explorer, a pioneering free-swimming robot, launched in 1995, which revolutionized deep-sea exploration by expanding scientists' reach into the deep.
Unlike human-occupied submersibles or vehicles connected by cables to surface ships, Sentry and ABE can survey wide swaths of undersea territory on dives lasting a day or more. The autonomous underwater vehicles, or AUVs, are pre-programmed to maintain a designated course but have enough decision-making capacity to avoid collisions with seafloor terrain. They are equipped with sonar to navigate and to map the seafloor and arrays of sensors that can measure water temperature and salinity, for example, or "sniff out" telltale chemicals that signal places and phenomena that scientists want to investigate.
AUVs can "work like bloodhounds," said WHOI engineer Dana Yoerger, who teamed with WHOI engineers Al Bradley and Barrie Walden to design both ABE and Sentry. "When they find something we're interested in, they can ‘bark' and then return from the ‘hunt.' " Or, as Sentry did on its premiere mission, it can make high-resolution maps of the seafloor.
Sentry's unconventional shape
"As expected on its maiden voyage, Sentry had some 'teething' problems," said John Delaney, a University of Washington (UW) oceanographer and the expedition's chief scientist. Nevertheless, "Sentry has given us a survey with great precision and resolution. These maps will help with the installation of the primary nodes of a networked observatory on the Juan de Fuca tectonic plate," he said.
♦ You can read the complete article in the online edition of Oceanus.