The main goal of the Trajectory subsystem is the study of the orbit of the satellite and the research of the space environment for a given orbit. The space environment includes regions with high fluxes of high-energy particles which can threaten the electronics and the mission. Furthermore, selecting the correct orbit is a major necessity both at mission and at a system level. The orbit must be such that there is enough time to run the scientific experiment while also keeping the orbital lifetime at a minimum, in order to avoid the creation of space debris.

All of the above are achievable using theoretical concepts and simulation software. For the orbit, our team has a strong background in both classical and orbital mechanics in order to determine the correct orbit. After that and with the assistance of specialized simulation software (GMAT, STELA, STK) we simulate the orbit of our nanosatellite. We track the satellite throughout the orbit and extract the expected orbital lifetime of the satellite with high accuracy. Our last study showed that the expected lifetime of the satellite varies from 7 to 14 months depending on the orientation of the cubesat.

GMAT Altitude (km) vs Time (days) diagram for the best case scenario

Using additional software (DRAMA/MASTER) we calculate the probability of collision with a secondary object, either a spacecraft or space debris. We must ensure that the satellite will have a direct entry in the earth’s atmosphere (below 120 km) which means that the cubesat will not orbit the earth at this height and will break down (?) due to the high friction of the atmosphere.

Concerning the radiation environment, we study the radiation environment at the satellite’s altitude. Our main focus is the Inner Van Allen belt, which extends above the South Atlantic Ocean (forming what is called the South Atlantic Anomaly), where charged particles are trapped due to the fluxuation of the magnetic field. The energy of the trapped particles in that area is extremely high so it’s important to simulate the radiation environment. In order to achieve this we use SPENVIS and OMERE, trying to extract results about the dose received by the cells and the electronic components of the satellite during the mission.

OMERE instantaneous energy spectrum along the orbit for trapped protons of 40.00 MeV

An ongoing field for the Trajectory subteam is the study of the mission with orbit optimization. In reality ensuring a steady orientation throughout the mission of the satellite it’s extremely hard. That’s why we are currently exploring how to simulate a disturbed orientation through time. We want to explore the life time of the cubesat in such a case and how the mission will be affected.