Development of the wide-swath and high-resolution optical imager onboard advanced optical satellite (ALOS-3)

Abstract

JAXA has developed the Advanced Optical Satellite (ALOS-3) as a successor to the optical mission of the Advanced Land Observing Satellite (ALOS) "Daichi" (2006-2011) since FY 2016. The wide-swath and high-resolution optical imager (WISH) is the main instrument of ALOS-3 and equipped with a panchromatic (Pa) band and 6 multispectral (MS) bands. For the optics of WISH, a large off-axis four mirror anastigmat type has been selected to achieve both highresolution (0.8 m Pa, 3.2 m MS) and wide-swath (70 km). The proto-flight model (PFM) of all mirrors has already in the precision polishing process, and highly accurate measurements of large off-axis aspherical surfaces (primary and tertiary mirror) are carried out both in a contact and a non-contact method. The verification concerning the high precision assembly of the large off-axis optical system was also carried out using the structural model which is manufactured with the same design for the PFM. Manufacture and test of the PFM of WISH would be conducted over the next one year and the PFM would be delivered to the ALOS-3 satellite system within FY 2019. ALOS-3 is scheduled to be launch from Tanegashima Space Center in FY 2020.