Optical trades for evolving a small arcsecond star tracker

We present a series of system performance models for nanosatellite star trackers. Many Earth-observing missions rely on spacecraft body motion to track ground targets. These operational scenarios lead to requirements for arc-second-accuracy attitude estimates during body motion at rates of up to 1 deg/s. Achieving these performance targets with a small sensor presents a challenge. We develop models to predict sensor availability and accuracy in terms of a number of optical design parameters. Starting from the baseline optical design of the Sinclair Interplanetary ST-16, we explore strategies for improving the sensor accuracy. We highlight distinctive features of the trade-space relative to more conventional star tracker design. Our discussions include an overview of system-level trends and an analysis of promising point designs. Results from these trades are valuable for prioritizing further development.