Introduction Feasibility study model
OGC 10-135 EO Satellite Tasking Extension for SPS
For some EO systems, feasible acquisition segments can be estimated long in advance and be provided directly in the results. For each planned segment, several properties are
then specified such as the date and time of acquisition, the combination of platform, instrument and mode used to acquire the segment, acquisition angles and ground
footprint of the segment, etc... The customer can then see the exact segments that will be acquired for him.
For other EO systems, such as highly agile satellites, feasible segments are not known in advance due to the possibility of acquiring multiple areas of the earth at a given instant in
time i.e. by pointing the satellite. In such cases, a frequent re-optimization of the satellite work plan with respect to the latest weather conditions especially for optical
instruments or other criteria is often done in order to satisfy a maximum number of customers. The consequence is that only an estimated list of potential segments can be
generated with no certainty that these segments will actually be acquired exactly as planned.
One common method to solve the problem of work plan optimization for agile satellites is the division of the region of interest in several smaller sub-areas called grid cells that
are processed individually in a statistical manner. Since the actual chosensuccessful segment covering each cell is not known with certainty at the time of the feasibility study,
statistical information is instead given to indicate the chance of successfully covering each cell, as well as the overall chance of successfully covering the whole area before the
end of the requested time window. Note that these probabilities can take into account climate, weather and satellite workload conditions, as indicated in the feasibility study.
In such a case, the feasibility result contains a list of cells in addition to the list of planned segments planned segments are optional if cells are given. Each cell feasibility
assessment can also include information such as the estimated date of success and the date of the first possible attempt. For advanced users, it is also possible to include all
possible acquisition attempts for each cell instead of a single estimated segment per cell in the feasibility response.