Scientific techniques - Landers
Landers & Seafloor Observatories
A lander is a system that can be ‘landed’ on a remote or inhospitable location to take measurements before being brought back so the information gathered can be recovered. We have learned about the surface of the Moon and Mars using landers sent through space. In a similar way, marine scientists use landers that can be sent to the deep seabed to carry out a pre-determined work programme.
These benthic landers work on a simple principle. When they are sent to the seabed they carry ballast weights to hold them in place. Special release mechanisms hold these ballast weights until they are triggered to drop them. Once dropped the landers become buoyant and float back to the surface where they can be collected by a research ship.
There are many advantages to using benthic landers. Research ships are very costly and can only work in good weather conditions, often just in the summer months. Long-term landers can be deployed in the summer and left in place for many months, sometimes over a year, gathering information on how the deep-sea environment varies through the seasons. A lander will take a few hours to set in place but will gather information continuously for long periods of time. Unlike manned submersibles or ROVs, landers are less likely to disturb animals at the seabed so are a good way of recording their behaviour over time.
Benthic landers have been put to many uses from time-lapse photography to detailed study of the chemistry of the deep seabed – limited only by the instruments that are suitable to use on them. A major disadvantage of the benthic lander approach is that they are limited by the on-board power and memory any one lander can carry.
In the last few years exciting developments have begun to create networks of deep-sea recording stations linked together with cables back to the shore. These seafloor observatories, often evolving from existing systems used to monitor for seafloor earthquakes, would receive power externally and be able to transmit data back to shore. Perhaps soon we will be able to log onto a web page and view a live seafloor observatory showing a cold-water coral reef.