Initial orbit determination using Doppler shift of Fraunhofer lines

Techniques for tracking objects in low Earth orbit include line-of-sight angle measurements and range measurements using RADAR or laser reflection. However, active ranging techniques are less effective for higher orbits because of the greater signal loss from distant targets. In this paper, using computer simulation, we show how incorporating measurements of the Doppler shift of Solar Fraunhofer lines can improve initial orbit determination. Results indicate that for Doppler measurement errors of less than 5m/s, prediction accuracies for some orbital configurations can exceed Gooding's angles-only method, while using only two observations of the target.