TSC-1 Optical Payload Hyperspectral Imager Preliminary Design and Performance Estimation

1. Introduction

1.1. TSC-1 Mission, Context and Impact on Technical Choices

Thai Space Consortium (TSC) comprises twelve Thai national organizations led by the National Astronomical Research Institute of Thailand (NARIT), the Geo-Informatics and Space Technology Development Agency (GISTDA), the Synchrotron Light Research Institute (SLRI) and the King Mongkut’s University of Technology North Bangkok (KMUTB). The long-term objective of the consortium is to elevate the capacities to design, develop and test space optical payloads in Thailand. In this context, the objective of the TSC-1 space mission is to send into space a satellite made of one platform, one optical payload dedicated to Earth observations, and one space weather payload. The optical payload would consist of hyperspectral imager pledge data cubes in the visible band. The Ground Sample Distance (GSD) is equal to 30 m, while the spectral sampling is equal to 5 nm/pixel. Therefore, the final spectral resolution is equal to 10 nm when the entrance slit of the spectrometer covers two rows of pixels.

The NARIT Center for Optics and Photonics (COP) is responsible for the development of the TSC-1 optical payload. NARIT COP has a proven experience in the development of the optical system for astronomical applications with wide-field cameras and low- and high-resolution spectrographs successfully commissioned on the 2.4 m Thai National Telescope (TNT) [1,2,3,4,5]. A space-based hyperspectral imager thus constitutes the next step in the development of optical systems at NARIT COP.

TSC-1 Earth Observation optical payload constitutes the first optical space system for a small satellite developed by Thailand. We thus decided to restrict some technical choices to guarantee the payload’s feasibility. We decided to select only spherical or aspherical optical surfaces and to put priority on using on-axis optical surfaces. We thus decided to avoid using freeform optics for this first optical payload. We want to develop one payload able to perform coastal, ocean and land observation similar to Sentinel-3 OLCI [6] that focuses mainly on Thailand. With this starting point, we will have no constraints on the revisit time and temporal average. Instead, we can have a better spatial resolution and an SNR equal to 100. This targeted application requests a spectral domain from 400 nm to 1000 nm compatible with COSTs CMOS spectral range. The volume/mass of the...