The SPOT-5 mission

Abstract

Since the launch of its first satellite, in 1986, the SPOT system makes regular images of the Earth available for commercial applications. SPOT-4, to be launched in 1997, will improve the system performances with the addition of a medium i.r. channel. The next step is foreseen in 1999 with SPOT-5, which will further improve the system with a twice better resolution and an along track stereo imaging capability. It will then be possible to get 1:50,000 scale or 25,000 scale standard maps and digital elevation models, under accessibility conditions considerably better than those allowed by the current off-track stereo capability. SPOT-5 is designed so as to reuse the platform and instrument developments of SPOT-4 to the maximum extent. The fore/aft stereo is realized simply by tilting the instruments on top of the satellite. Two configurations are still being contemplated, one with two instruments and one with three instruments, offering wider mission capacity. The fore/aft stereo imaging imposes that the flight kinematics is properly adapted. The enhanced instrument, HRG, encompasses a 5 m resolution panchromatic band, in addition to the recurring ones. The focal plane assembly is therefore re-designed. The optical performances of the recurring telescope at the new resolution have been validated by tests and will be secured by some structural and optical in-depth analysis and improvements. To cope with the different data rate modes and the anticipated mission scenario profiles, a new payload data management system is designed, based on a solid state recorder. The platform subsystems are kept identical to those of SPOT-4 and the propulsion module structure will be adapted in case of a solution with three instruments.