1 ASTER OBSERVATION SCHEDULING ALGORITHM

The Advanced Spaceborne Thermal Emission and Reflectance Radiometer (ASTER) is a multi-spectral imaging radiometer with 14 spectral bands of VNIR, SWIR and TIR, 60 km imaging swath, and 15-90 m spatial resolution, to be launched on NASA’s Earth Observing System AM-1 (EOS AM-1) in early summer of 1998. The scheduling algorithm and Scheduler software was developed in order to maximize the scientific content of each schedule. The Scheduler is able to generate an ASTER activity schedule of any length by specifying the start and end times of a schedule as input parameters. For any length schedule, the Scheduler determines ASTER activities one day at a time. The Scheduler divides each day into a series of short timesteps (several seconds), for the purpose of prioritization. Prioritization is the process of ranking possible observations, so that the observation opportunities with higher scientific or programmatic value are given higher probabilities of being scheduled. The Scheduler uses the prioritization function to calculate a priority for each potential observation. The weighting factors in this function are prescribed by the Science Team, and may be modified as the mission progresses. The prioritization function uses information from all data acquisition request parameters requesting a possible observation, along with some time-dependent and instrument information, as input variables. There are 11 of Priority Sub-Functions such as; Data collectio