  The operation-planning of satellites, aimed at introducing a certain level of
supervised automation during the execution of the operations, poses a great
challenge to both designers and operators. From one side, the routine
operations for an Earth Observation mission are predictable and typically
repeatable; both these aspects are suitable for computerisation. On the other
hand, not every non-nominal scenario can be anticipated and correctly
formulated in terms of operations. Dealing with contingency presents risks
which need to be addressed as early as possible, hopefully already during the
operations preparation. It is also possible, however, to intervene at a later
operational stage of the mission, optimising the tools already in use to
support the operations execution. In this paper, having in mind the idea to
improve existing processes in place at EUMETSAT, we present an algorithm able
to reschedule the spacecraft's activities in case of anomaly. The main goal is
to support the decision-making process while overcoming contingencies both
avoiding overloading the spacecraft and planning engineers and ensuring the
continuity of the mission, in particular giving the highest priority to the
onboard computer memory size and data quality. We tested the method with the
data of Sentinel-6, which carries the altimeter POSEIDON-4 operated by
EUMETSAT, and the results are hereby presented.
