Expendable benthic lander (XBL)

Abstract

Observatories on the sea floor are about to permit long term observations of physical and chemical processes. Most of these observatories will deliver their measurements ashore in real time or near real time and many will derive power from a cable that connects them to shore. The cable is both empowering and limiting insofar as it permits long deployments and real time data return but restricts observations to regions where the cable has been laid. There remains a need for observatory type arrays of sensors where cables have not been emplaced. The expendable benthic lander is an instrument that can be deployed in such an array. The requirements for such an instrument are that it be inexpensive so that large numbers can be deployed in an array, easily deployed so that costs of laying the array are modest, capable so that physical and chemical properties can be resolved at the speed and sensitivity required to understand processes of importance, and recoverable so that the data may be analyzed in detail. Physical instrument recovery is a desirable attribute but not as important as data recovery. Since data may be recovered even if the instrument is lost, the term expendable is applied to this benthic lander although this is not the primary mode of use.