Autonomous Planning for an Agile Earth-Observing Satellite

Most of the currently active Earth-observing satellites are entirely controlled from the ground: observation plans are regularly computed on the ground, uploaded to the satellite using visibility windows and then, executed on-board as they stand. Because the possible presence of clouds is the main obstacle to optical observation, meteorological forecasts are taken into account when building these observation plans. However, this does not prevent most of the performed observations to be fruitless because of the unforeseen presence of clouds. To fix this problem, the possibility of equipping Earth-observing satellites with an extra instrument dedicated to the detection of the clouds in front of it, just before observation, is currently considered. But, in such conditions, decision upon the observations to be performed can no longer be made off-line on the ground. It must be performed on-line on-board because it must be performed at the last minute, when detection information is available and because visibility windows between Earthobserving satellites and their control centers are short and rare. In this paper we present a generic architecture made of a reactive decision making task and of a deliberative planning one. Then we show the mechanisms that can be used in both modules for the particular case of an agile Earth-observing satellite.