Conceptual Optical Design of a Synthetic Aperture Telescope by Small Satellite Formation Flying for GEO Remote Sensing

Abstract

Recently, a spatial resolution of several meters from LEO has been realized in small satellite remote sensing. However, it is difficult to increase a temporal resolution in LEO remote sensing. Therefore, GEO remote sensing which enables observation of high temporal resolution from GEO or its nearby orbit is getting important. In order to obtain enough spatial resolution in GEO remote sensing, an optical system having a diameter of several meters is required because of the diffraction limit. It takes huge cost to realize the optical system with such a large diameter due to manufacturability and required accuracy. To solve these problems, we propose a synthetic aperture telescope by small satellites formation flying. The synthetic aperture telescope is composed of mirror satellites constituting a primary mirror of the telescope and an imaging satellite having a focal plane assembly. By optically synthesizing the light collected by mirror satellites with the imaging satellite, a virtual large aperture telescope is constructed in orbit. In this paper, observations at near infrared to short wavelength infrared are assumed and required specifications are shown. Moreover, we describe optical performance of the synthetic aperture telescope and an adjustment method of the optical system by applying the adaptive optics technique.