Development of the MBARI mapping AUV
MBARI has developed an autonomous underwater vehicle (AUV) with capabilities to map the seafloor with higher resolution than is possible with hull-mounted or towed sonar systems.
The MBARI mapping AUV is a torpedo-shaped vehicle equipped with four mapping sonars that operate simultaneously during a mission. The sonars are a swath multibeam sonar, two sidescan sonars, and a sub-bottom profiler. The multibeam sonar produces high-resolution bathymetry (analogous to topography on land), the sidescan sonars produce imagery based on the intensity of the sound energy's reflections, and the subbottom profiler penetrates sediments on the seafloor, allowing the detection of layers within the sediments, faults, and depth to the basement rock. All components are rated to 6,000 meters depth. The vehicle is launched on programmed missions and runs on its own battery power until it returns to the ship, as programmed, for recovery.
In honor of MBARI's long-time Board member Dr. D. Allan Bromley of Yale University, who passed away in 2004, the mapping AUV was christened the D. Allan B.
Purpose and Motivation
A fundamental activity in oceanography is to use mapping technology to image the structure and character of the seafloor. Sonars that are hull-mounted or towed do provide high quality seafloor maps in shallow water, but cannot show elusive seafloor features such as lava flows or slumps at depths of more than 100 meters. 1
Using platforms mounted with high-frequency sonars that can operate in deep waters is required in order to achieve one meter resolution of the seafloor. These platforms consists of expensive, noisy, and erratic submersibles.
MBARI has created an autonomous underwater vehicle (AUV) to efficiently map high-resolution images on the ocean floor.
Autonomous underwater vehicles provide important advantages for seafloor mapping, especially in the deep ocean. Since high-frequency sound is required to obtain high-fidelity maps of the seafloor, and high frequencies are attenuated by sea water, it is necessary to get close to the seafloor to produce the highest quality maps. Typically this is done by towing sonars close to the bottom. However, in deep water, especially near rough seafloor, this can be dangerous and slow and produce data contaminated by ship motion. The AUV provides a faster, more nimble platform to produce very high-quality data sets.
New high-resolution maps of the seafloor are expected to:
- Drive new science (such as sediment transport from shelf to deep sea)
- Enable deep-sea resource management (such as habitat surveys)
- Help in planning & installing seafloor observatories (such as MARS)
1 Paduan, J.B., Caress, D.W., Clague, D.A., Paull, C.K., Thomas, H., “High-Resolution mapping of mass wasting, tectonic, and volcanic hazards using the MBARI Mapping AUV”, International conference on seafloor mapping for geohazard assessment, Forio d’Ischia, Italy, May 11-13, 2009.