The Australian Space Eye: Studying the History of Galaxy Formation with a CubeSat

摘要

The Australian Space Eye is a proposed astronomical telescope based on a 6 U CubeSat platform. The Space Eye will exploit the low level of systematic errors achievable with a small space based telescope to enable high accuracy measurements of the Cosmic Infrafred Background (CIB) and low surface brightness emission around nearby galaxies. To date absolute measurements of the CIB have proven elusive; the variability of atmospheric emission and scattering at these wavelengths make ground based measurements difficult while attempts to use sounding rockets have struggled to accumulate sufficient exposure time. An dedicated orbital telescope is required for a robust measurement, and Space Eye has been designed to fill this role. The scientific payload of Space Eye is a 90 mm diameter, clear aperture, all refractive telescope for wide field imaging using a set of 6 broadband filters in the i' (700-850 nm) and z' (850-1000 nm) bands. The telescope design is optimised to minimise all sources of stray light which, when combined with the advantages of the space environment, will enable the most accurate measurements of the CIB so far. This project is also a demonstrator for several technologies with general applicability to astronomical observations from nanosatellites, in particular arcsecond level instrument pointing stability and efficient image sensor temperature control. These crucial capabilities are commonplace in larger scientific satellites but have yet to be flight proven in a CubeSat platform. For the former we have developed a two stage ADCS concept combining high precision star trackers, reaction wheels, and sensor shift image stabilisation in the science instrument focal plane. Detailed system modelling, incorporating in flight performance data for many of the components, has verified that the design can achieve sub-arcsecond level pointing stability. Wc have also designed a thermal control system and concept of operations that enables passive cooling of the ima