Autonomous deep-ocean lander vehicles; modular approaches to design and operation

Deep-ocean landers are autonomous vehicles that descend to the sea floor and function autonomously without any connection to the surface for periods of 12 h to one year. At the end of the mission, ballast is released by acoustic command from the surface and the lander ascends by virtue of its buoyancy. Landers are made up of two components: basic delivery system; and the scientific payload. Experience with over 20 lander types within Europe has established some common design principles. The Aberdeen compact ATTIS lander combines experiment management, data storage, acoustic telemetry to the surface and ballast release control all within one unit. More typically a modular approach is used with the delivery system separated from the scientific payload. The scientific payload has its own power supply and different experiments on the same lander are autonomous so that failure of one does not affect the rest of the system. A modular architecture with the ability to change scientific payloads has proved most flexible and reliable. A CAN type network provides central data logging whilst maintaining functional autonomy of the different experimental modules.