Feasibility Study on Thermal Design for Synthetic Aperture Telescope Using Formation Flying Micro-satellites

Date

7/10/2022

Journal Title

Journal ISSN

Volume Title

Publisher

51st International Conference on Environmental Systems

Abstract

Due to global warming, forest fires are becoming more frequent and serious. We study the development of a forest fire early detection system named Formation Flying Synthetic Aperture Telescope (FFSAT). Operating the synthetic aperture telescope constructed by multiple Formation Flying (FF) micro-satellites in geostationary orbit can provide both frequent and high-resolution monitoring of the target area. In addition, this system significantly reduces launch costs because the satellites are smaller and lighter than a single mirror telescope satellite with the same aperture size. The observation wavelength of the FFSAT is 4-um to detect the forest fire flames. Therefore, it requires the ultra-precise relative attitude and position control of about 1/10 of the wavelength, or less than 0.4-?m. Since thermal strains of the satellites are not negligible to this precise system, we constructed a thermal structure model of the FFSAT to evaluate and minimize the effect of thermal strains on the optical system. FFSAT consists of one imaging satellite and six mirror satellites that form one large mirror surface with a diameter of 5.82 meters. The primary mirror of each mirror satellite is supported by a piezo stage to control sub-?m displacements in six degrees of freedom, and the imaging satellite has a Deformable Mirror (DM) to correct the incidence light from the mirror satellites. As a result, the displacements of the optical planes by the thermal strains of the mirror satellites and the imaging satellite are less than several tens of ?m. It is within the dynamic range of the piezo stage and the DM. We confirmed that the optical surface could be corrected on the sub-?m order.

Description

Shinichi Yokobori, The University of Tokyo, JP
Ryo Suzumoto, The University of Tokyo, JP
Norihide Miyamura, Meisei University, JP
Satoshi Ikari, The University of Tokyo, JP
Shinichi Nakasuka, The University of Tokyo, JP
ICES107: Thermal Design of Microsatellites, Nanosatellites, and Picosatellites
The 51st International Conference on Environmental Systems was held in Saint Paul, Minnesota, US, on 10 July 2022 through 14 July 2022.

Keywords

Deformable Mirror, Thermal Strain, Formation Flying, Synthetic Aperture Telescope, Micro-satellites

Citation