Design and calibration process of solar sensors for small satellite missions

Abstract

In combination with magnetometers, solar sensors are one of the most used instruments for determining the attitude of small satellites. These devices use the photoelectric effect to produce an electrical current. This electrical current, or the voltage associated with the electrical circuit of the solar sensor, is measured in order to compute the angle of incident of the sun with the normal direction of the sensor. Then, together with the computed angles of other solar sensors on different faces of the satellite, the sun's direction in relation to a spacecraft can be calculated. Solar sensors are simple devices whose low-cost design based on photodiodes can be developed by students. During the design and fabrication process of a solar sensor, one of the most important tasks is the accurate estimation of the sensor response in the space radiative environment. It is possible to simulate the Sun’s radiation spectrum, but the equipment and facilities needed are costly for a university project. In this paper, the design and calibration process of satellite solar sensors carried out together by students and teachers from the Master's degree in Space Systems (MUSE) from the Universidad Politécnica de Madrid is described. The process uses a calibration method that calibrates the photodiodes for space use without simulating the Sun’s radiation spectrum in the laboratory