Distortion Optimized Off-Axis Three Mirror Anastigmat for Space Domain Awareness

Abstract

With the progression of spaceflight and cost effective launch vehicles as well as develop-ment of small high performance satellites that proliferate throughout cislunar space, space domain awareness in the cislunar region has become a topic of utmost importance to the US government and its partners. By leveraging the technology of Time Delay Integration CCD imagers combined with a compact reflective triplet Three Mirror Anastigmat Off-Axis Telescope, a high performance imaging satellite is designed for deployment throughout cislunar space. By injecting a constellation of these TDI TMA telescopes at different distant retrograde orbits about the moon, we establish a large field of regard with which to detect, track, and characterize foreign entities. The optical design is optimized to minimize variance in distortion across the TDI interval in an effort to improve imaging and point source tracking performance specific to the unique layout of a stacked 3 channel TDI imager mosaic. Unlike traditional detectors, TDI detectors and their relative performance depend not on the total distortion across the field of view, but rather have their performance degraded by excessive change in distortion across the TDI interval, such that each pixel in a given column sees the same image with the same degree of distortion. The proposed optical design is optimized as such to reduce performance loss due to a non-constant distortion gradient.