Maximization of LEO Nanosatellite's Transmission Capacity to Multiple Ground Stations: Orbit Selection and Requirements on Attitude Control

This paper presents the study of an optimized orbital configuration for a 3-axis stabilized 6U LEO nanosatellite that accommodates a polarized calibrator designed to transmit a calibrated signal to seven ground telescopes devoted to Cosmic Microwave Background (CMB) detection with an accepted maximum absolute pointing error of 4 arcmin; visibility windows and revisit time are maximized by orbit selection and active attitude control considering no possibility of orbital mobility. The solution approach is divided in two parts: in the first part, a dedicated sensitivity study is conducted to find the optimal orbital parameters that maximize the mean contact time between the spacecraft and the list of ground telescopes; in the second part the identified promising orbital configurations are propagated to evaluate the attitude change maneuvers needed during the passage above each telescope to guarantee continuous signal transmission. The results of the sensitivity study report the maximum values for the duration and frequency of the CubeSat-to-Ground station visibility periods. The required performance in terms of pointing accuracy and repointing velocity is later used to propose an attitude control loop for precision pointing and to define a commercial off the shelf Attitude Determination and Control System (ADCS) architecture.