Development of Albedo Module for Open Source Astrodynamics Software

Çilden Güler D. (Executive) , Hacızade C., Kaymaz Z.

TUBITAK Project, 2021 - 2022

  • Project Type: TUBITAK Project
  • Begin Date: February 2021
  • End Date: February 2022

Project Abstract

Spacecraft are used for lots of different purposes such as scientific, communication, meteorology, astronomy, remote sensing, navigation, surveillance, observation, under the mission types of planet orbiting or interplanetary. These crafts or the devices on them are to be directed in certain directions or points to accomplish the mission requirements. Certain flight modes are used to ensure a successful attitude pointing and different performance criteria can be used for each mode. For example, safe mode can be activated when low power is required. Or, redundant sensors can be used for sanity checks of the main sensors. For such purposes, sensors such as magnetometers and sun sensors, which are less accurate but require less power, are cheaper and smaller, can be used. Sun sensors are frequently used in both satellites orbiting around a planet or an interplanetary spacecraft in the solar system. Coarse sun sensor (CSS) in this category measures not only radiation from the sun but also the planet's albedo. These measurements are known to cause erroneous outputs in the flight software if the albedo model is not considered. Moreover, albedo values ​​change according to the season, geography, time and cloudiness parameters. In this project, albedo models will be examined by taking into account such changes. The basis of the project is to develop an albedo module for open source astrodynamics software and make it available to public. In addition to sun sensors, albedo has a significant impact on many sensors and subsystems. For example, it can be an important factor in the selection of optical sensor systems such as camera or star tracker or in determining the characteristics of power/thermal subsystems. For this reason, the albedo module to be developed will be designed in a generalized structure that can be applied to any instrument and celestial body. Another important aim of the study is to investigate the effect of albedo on spacecraft attitude estimation. For this purpose, the effects of albedo in terms of attitude estimation will be investigated by implementing albedo on sun sensor measurements. The effect of albedo on sun sensor measurements has been studied in particular for satellites orbiting around Earth, but other planets or celestial bodies are not addressed in terms of attitude of a spacecraft. In order to fill this gap, the albedo effect on the sun sensor from the Earth-Moon system and Mars planet will also be investigated through different simulations.