Dan Davis, Luther College assistant professor of classics, recently returned from his third deep-sea excursion in as many years.
Most deep-water surveys incur massive costs due to the large research vessel, large remotely operated vehicles tethered to the ship and expensive equipment for keeping the ship on station, to the tune of $50,000 per day. To keep a ship on station, the vessel requires a sophisticated GPS system and large, powerful thrusters that constantly adjust the ship's position, locking it over the dive site. After sailing with National Geographic for two months during the summer of 2012, Davis set out to demonstrate that the same kinds of data can be collected for a fraction of that cost, while still involving students and serving as a teaching endeavor.
Daniel Faas, Luther class of 2013, traveled to the South Aegean Sea in August as Davis' assistant. Faas assisted with data post-processing, cataloging, site mapping and artifact registration.
"Dan was integrated into the team on day one. Fortunately, Dan's interests in computer and software design came in handy as he was trained to process sidescan sonar data, along with other data streams that included water current, density, temperature and other oceanographic parameters.
"For me, it was exciting to see him immerse himself in data processing and taking a keen interest in how to interpret sonar data as it relates to geological formations and shipwrecks. The other senior members of the team also regarded Dan with great respect and admiration for his enthusiasm and energy," said Davis.
Davis, Faas and the rest of the crew were aboard the Sail-Training Ship Bodrum, a modest 120-foot, two-masted sailing/school ship. Using an Autonomous Underwater Vehicle, they surveyed the seabed of the southeast Aegean Sea near Bodrum, Turkey, for both historic shipwrecks and interesting geological features. The crew's AUV survey amounted to about 15-20 percent of the cost of a large vessel excursion and gathered much of the same type of information.
The team also found success in locating two new ancient shipwrecks in addition to the 26 that had been found in previous sessions in the same area. The STS Bodrum crew is studying the data to determine the wreckages' date and origin.
The AUV, which looks essentially like a long torpedo, was programmed to survey the seabed at a depth between 300 and 2,000 feet using a suite of tools: sidescan sonar, multibeam sonar, digital still photos, and high-definition video. Davis and his crew dropped it in the water in the morning, let it do its work all day, then picked it up toward evening.
"The biggest differences were in the pace of the data processing and the amount of down time for the team. On the large research ship, operations go 24/7 with three teams that take watches that last four hours on, eight hours off. This results in a constant stream of data that requires processing during our off-watch hours. For this low-budget survey, we could launch the AUV first thing in the morning, move near shore, anchor, and process data from the previous evening, then go for a swim and relax in the cool, crystal blue waters of the Aegean Sea.
"The amount of data that the AUV collects can be processed in a rather short amount of time, once everyone learned the steps and the software," said Davis.
For his two-week trip in August, Davis served as chief archaeologist, responsible for identifying shipwrecks, researching their origin, date and cargo based on archaeological evidence.
Sponsors for the project included deep-sea explorer Robert Ballard, who discovered the Titanic; the Institute for Exploration and Ocean Exploration Trust.
For highlights from this excursion and other recent explorations go to: http://www.explorationnow.org/.