Development of the wide-swath and high-resolution optical imager (WISH) onboard Advanced Land Observing Satellite-3 (ALOS-3)

Advanced Land Observing Satellite-3 (ALOS-3) is one of the follow-on missions of ALOS, also called "DAICHI" (2006−2011), and it takes over the optical mission from ALOS. The goal of the ALOS-3 mission is to contribute to the disaster monitoring and updating of geo-spatial information, as well as the environmental monitoring of coastal and vegetation areas. The main payload of ALOS-3 is an optical camera, named wide-swath and high-resolution optical imager (WISH). It has a resolution of 80 cm (panchromatic) and 3.2 m (multispectral) at nadir together with a wide-swath of 70 km by employing an off-axis large FMA (Four Mirror Anastigmat) telescope. The detectors on the focal plane are TDI-CCDs, with observational bands of panchromatic and six multispectral bands, including "coastal (0.40 - 0.45 μm)" and "RedEdge (0.69 - 0.74 μm)" in addition to red, green, blue, and near-inferred. In order to achieve high optical performance, the technical challenges specific to this satellite telescope have been required in all the processes of design, manufacturing, and testing. This paper presents an overview of the WISH and the development result of each process. All the processes have been completed without critical problems, and all the required pre-flight performance has been verified and reviewed.