Reflecting telescopes for an orbiting high-resolution camera for Earth observation

This feasibility study compares several optical configurations for an orbiting high-resolution (<1 m) panchromatic push-broom camera. This is an optical subsystem of the CIA (Camera Iperspettrale Avanzata, Advanced Hyperspectral Camera) project, promoted by the Italian Space Agency (ASI), aimed at high-resolution imaging for applications in Earth observation, mainly for environmental control, geology (especially volcanoes), and coastal and inland water monitoring. The study includes optics and radiometric analyses, used to select a fan of candidate optical configurations, including all the solutions suitable for the specific task, namely, Ritchey-Chretien with and without relay, Korsch, and Schmidt-Cassegrain on axis, off axis, and with relay. The result of a trade-off analysis, considering not only optical performance but also other aspects such as cost, volume, complexity, and technological criticality, shows that the Korsch configuration is currently the best compromise, and it is potentially able to satisfy all project requirements. However, the other configurations have advantages that may be considered in the whole-mission assessment. (C) 2006 Society of Photo-Optical Instrumentation Engineers.