Trajectory

Introduction

The main goal of the Trajectory subsystem is the study of the spacecraft’s orbit and its space environment. The study includes the mission analysis, the space debris assessment and the radiation analysis. Selecting the preferable orbit is a major necessity both at mission and system level.

It is crucial to obtain the proper duration of mission , so that there is enough time for the experiment to run, by minimizing debris formation and radiation exposure at the same time. Classical and celestial mechanics, together with various software tools are used for the orbit and radiation environment simulations and the debris study, all part of the so-called orbit optimization. Trajectory’s research is a dynamical process, meaning analyses are updated many times throughout the mission.

Mission Analysis

The mission analysis is based on orbital mechanics, and is carried through with simulation software, namely GMAT, STK and STELA. Using these tools, the subsystem studies different possible scenarios for the trajectory, which derive from various parameters’ values. The orbit depends greatly on orbital elements, atmospheric models, satellite’s geometry and mass, geomagnetic and solar activity. Recent results indicate that the expected AcubeSAT ‘s lifetime  extends from 1 up to 20 years.

Space Debris

Space debris analysis ensures the compliance of the cubesat’s orbit, structure and operations with international and european debris mitigation policies. It includes the assessment of probable debris collisions  and break-up events, with simulation tools, such as DRAMA. Furthermore, safe ways of passivation, disposal and atmospheric re-entry are studied, in order to minimize the risk of space waste generation. Members examine multiple failure cases that could lead to more debris, and try to prevent them.

Radiation

Concerning the radiation environment, the subsystem studies the radiation environment for the various available orbits that suit your mission. The 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 fluctuations of the magnetic field. The energy of the trapped particles in that area is extremely high so it is important to simulate the radiation environment.

 In order to achieve this, members use SPENVIS and OMERE, trying to extract results about the dose received by the cells and the electronic components of the satellite during mission. Nowadays, the FASTRAD software is used for performing Monte Carlo Simulations in 3D-Models for Radiation Transport Problem, which will help  improve the accuracy in the dose and the LET received.