Determination of the orbit of unknown ultra-small spacecraft based on the circular perturbed motion model and Doppler frequency shift measurements
A. A. Spiridonov, A. G. Kezik, V. A. Saechnikov, V. E. Cherny, D. V. Ushakov
Moscow University Physics Bulletin 2020. N 5.
In this work, the determination of the orbit of an unknown ultra-small spacecraft based on Doppler measurements of the frequency of the telemetric signal in several orbits with a limited number of data on one pass is studied. The reception and processing of telemetry radio signals was carried out by the ground station of the Belarusian State University in the amateur radio frequency range of 435-445 MHz with an interval of 6 minutes, two to three packets per flight with time intervals between telemetry receptions on adjacent turns in the range from 94 to 102 minutes.
In the model of perturbed circular motion, the radio signals of a small satellite were processed and the parameters of its orbit were determined. Based on a probabilistic estimate of the elevation angle and Doppler frequency shift of an unknown ultra-small spacecraft from 10 and 20 measurements, a set of orbital parameters (T, i, u, Omega) is determined for the estimated time of receiving telemetry signals. For antenna systems, the dynamics of changes in elevation angle, azimuth and Doppler frequency shift of telemetry radio signals for the next flights of an ultra-small spacecraft are predicted.
Based on the obtained parameters, the University Ground Station successfully received and decoded telemetry packets of an unknown ultra-small spacecraft. Using the NORAD database of orbital parameters, the Chinese nanosatellite of the Cubesat (6U) LUOJIA-1 01 format (number 43485 in the NORAD system) was identified. The absolute errors in the prediction of altitude and azimuth did not exceed 3o, and the absolute error in determining the Doppler frequency shift did not exceed 250 Hz, which is sufficient for the successful reception of telemetric radio signals and their decoding.Show Abstract