Megha-Tropiques: mission planning, analysis, and operations

Climate in the tropics is primarily influenced by variations in energy and water budget exchanges in the land/ocean/atmosphere systems. The interaction of these systems with the general atmospheric circulation is still not fully understood – one of the reasons why weather forecasts and predictions of climatic events are less accurate. The Megha-Tropiques mission, an ISRO-CNES (Indian Space Research Organisation–Centre National d’Etudes Spatiales) collaborative programme, aims to study water cycle and energy exchanges in the tropics, and use the data in climate and meteorology models. Megha-Tropiques is part of the Global Precipitation Measurement Mission, which is an international network of satellites. Of the four payloads on board, MADRAS is jointly developed by ISRO and the French space agency, CNES; SAPHIR and SCARAB completely by CNES; and GPS-ROSA is obtained from TAS-I (Thales Alenia Space Italia, Milan, Italy). GPS-ROSA supplements the geophysical parameters of the other payloads for atmosphere modelling. Mission planning involved integrating and interrelating the efforts of space and ground systems in realizing the operational system that provides the satellite-based science data meeting the turnaround time (TAT). Pre-launch simulations involved usage of a software simulator as a tool for network tests, training of spacecraft operation personnel, and validating the spacecraft health-monitoring software. The required operations were performed to characterize the payloads as well as to calibrate the various attitude sensors of the spacecraft. This paper summarizes mission planning and analysis aiding spacecraft configuration, pre-launch mission simulations, launch and early-orbit operations, and the on-orbit operational guidelines for Megha-Tropiques.