Space mission planning and operations

Indian Space Research Organization successfully carried out more than 40 space missions, during the last four decades, in the area of space sciences, spacecraft technologies, space applications and launch vehicle technologies. Mission planning and mission design are the most important multi-disciplinary elements in realizing these objectives. The present article describes the methodology followed in mission planning and mission design for different types of space missions of ISRO, bringing out the trade-off and inter-disciplinary nature of these activities. Important aspects of mission planning in the lift-off phase, the atmospheric and exoatmospheric phases of a launch vehicle are described. A number of conflicting mission constraints have to be addressed in designing an optimal and robust mission profile for the launch. In addition to reducing aerodynamic and structural loads, considerations related to flight safety and ground station visibility are important parameters. Special launch considerations are to be addressed in designing trajectories for lunar or planetary missions. Launch phase would extend up to injection of the spacecraft in the desired orbit. Thereupon, the spacecraft mission operations are divided into initial phase and operational phase. Initial orbital phase operations include, orbit raising and acquisition operations, and testing of the payloads. The operational phase of spacecraft mission covers, satellite health monitoring and maintenance, station keeping, special operations on the spacecraft, trend analysis and any contingency operations, all leading to gainful utilization of the satellite. A number of mission operations also have now become imperative for mitigating the detrimental effects of ever increasing space debris.