Site reconnaissance surveys for oil spill research using deep-sea AUVs

The National Institute for Undersea Science and Technology (NIUST) owns and operates two deep-sea AUVs [1, 2]. The International Submarine Engineering (ISE) built Eagle Ray a torpedo shaped, 2200 meter rated Autonomous Undersea Vehicle (AUV), typically operates 20 meters to 50 meters off the seafloor collecting multibeam and sub bottom data. Mola Mola is a 2000 meter rated hovering vehicle that records digital images with its primary sensor an AVT industrial camera typically from three meters altitude. Currently these AUVs provide deep site reconnaissance for instrument deployments and bathymetric and sub bottom surveys of selected areas for the Ecosystem Impacts of Oil and Gas Inputs to the Gulf (ECOGIG) consortium. The Eagle Ray AUV surveying at 50 meters off the seafloor, collects high resolution swath Multibeam Echo Sounder (MBES) and polarity preserved Sub Bottom profile data (SBP) along the nadir line of the vehicles dive track. The Mola Mola AUV is used for close-up high resolution photographic site investigations. The combination of these two AUV's is providing a unique tool to study seafloor morphology, sub bottom structure and provide high resolution imagery of targets of interest [3]. Data of the combined work of these two AUV's collected during the October 2012 Gulf of Mexico Research Initiative (GOMRI) funded ECOGIG cruise to MC297 and MC118 aboard the R/V Pelican will be presented at the meeting. Eagle Ray accomplished during this cruise 3 full length dives to a record depth of 1633 m and collected MBES and SBP data along 241 km of combined line length, covering an area of ∼30 km2. Mola Mola took over 12,800 images on 4 full length missions. One of these dives went to a vehicle record depth of 1612 m near MC297 finding and imaging a 3 × 3m size target on the ocean floor, previously deployed on an earlier consortium cruise. This paper will discuss the approach of using autonomous underwater vehicles to collect background data in support of deep sea research aimed at understanding the process of natural oil and gas seeps in the deep Gulf of Mexico from dives completed successfully in 2012.