A fractionated approach to coastal salinity measurement

Coastal salinity is characterized by large and variable salinity contrasts on relatively small spatial scales. Measurements of salinity at a resolution compatible with these coastal regions on a regular basis would provide new data for the monitoring of a key climate change variable in an as yet unobserved region. This paper describes an approach to measuring coastal salinity using the concept of fractionated satellites. The fractionated concept, developed by Owen Brown and Paul Eremenko of the Defence Advanced Research Projects Agency (DARPA), uses physical decomposition of the spacecraft and information integration to achieve a space system that is much more flexible and adaptable than its monolithic equivalent. Soil Moisture and Ocean Salinity (SMOS), the current European Space Agency (ESA) mission to measure sea surface salinity, already utilises information integration at a payload level to combine the information from the individual receiving antennas to form the image onboard the spacecraft, before it is transmitted to the ground. A coastal salinity measurement system that requires flexibility and reliability can be achieved through physical decomposition of the payload and information integration. This presents significant challenges in terms of the data handling, onboard computing and communications architectures employed as well as the orbits employed by the individual free flying modules and the accuracy to which they are maintained. We present some initial discussion and results from a concept exploration of a space system to measure coastal salinity.