Development of a polarimetric infrared space telescope for nanosatellites

Abstract

The purpose of this work is to develop a low-cost space telescope for Earth remote sensing that can be housed in a 12U CubeSat with a ground sampling distance (GSD) of 60 m at long wavelength infrared. It will use the three-mirror anastigmatic concept and commercial off-the-shelf components whenever possible. The main mission of the instrument is oil spill detection, especially in the ocean environment. Apart from the obvious functionality of this main mission, oil spill detection can be very useful for detecting aircraft that have crashed in the ocean. As secondary missions, this instrument can be used to map deforestation, find lost ships in the ocean, and help fight drug smuggling by finding camouflaged man-made objects. In order to fulfill these missions, the instrument will extract polarization information from the target. The optical design indicates that the optical performance of the instrument has a modulation transfer function >53 % at Nyquist frequency and a native GSD of 60 m and that the instrument is diffraction limited (wavefront error of 0.036 wavelengths and Strehl ratio of 95.77%). The mechanical design indicates that the maximum deflection caused by gravity induces a minimal error (smaller than one over one hundred and forty) when compared to the mean wavelength of operation. The radiometric analyses indicate that the instrument has an NEDT of 56.30 mK.