The project has two aims. The most obvious is to produce "climate data records" for sea surface temperature. SST is an "essential climate variable", which means that to understand and track climate variability and change, we need high quality records of how SST changes over time. With sufficient remote-sensing know-how, this can be achieved using infra-red imagery from Earth observing satellites.
The project has a limited lifetime, but the need for climate data records won't disappear. Therefore we have a second aim: in the process of delivering data, we will build a software system that can then be sustained to provide data in future. We don't know how that will be funded, at present, but nonetheless over the next 3 years the project will develop its software to a stage of being, in the jargon, "pre-operational".
The system won't be able simply to be run untended, even in an sustained (or "operational") mode, without maintenance of the science, and cyclic improvement to our techniques. This is because satellites come and go, and to get new observations to the standard required for inclusion in the SST CDR requirements ongoing Earth observation development work. Moreover, overtime, we discover how to make CDRs better, and therefore should reprocess the whole dataset consistently in the improved manner.
Thus, the system includes software and human experts, in a cycle of sustained production of data (as the observations come in) and periodic reprocessing. Conceptually it is like this: