Effects of Magnetospheric Environment on Polar Orbiting Satellites: A Case Study of PolarBeeSail Yiğit Çay 1 , Necmi Cihan Örger 2 Faculty of Aeronautical & Astronautical Engineering Istanbul Technical University Istanbul, Turkey 1 cayy@itu.edu.tr, 2 norger@itu.edu.tr Zerefşan Kaymaz Faculty of Aeronautical & Astronautical Engineering Istanbul Technical University Istanbul, Turkey zerefsan@itu.edu.tr Abstract––A solar sailcraft is the spacecraft that uses the solar radiation pressure force for acceleration and does not need any propellant other than the sunlight. PolarBeeSail (PBS) is designed as a solar sailcraft and a nanosatellite in 4U CubeSat shape and has 4 m x 4 m solar sail providing the satellite small but reasonable thrust levels. The PBS is a science oriented spacecraft. Its main objective is to investigate the polar magnetospheric regions using a plasma analyzer and magnetometer. Its lifetime is planned as 11 years, which is equivalent to one solar cycle. In this study, mission and design of PBS are given with the basics of the solar sail concept (or solar sailing). The Earth’s magnetic environment consists of various particles with different energy levels. The high energetic particles from the Sun and from other galaxies harm the spacecraft and decrease its efficiency. Among the several effects of the space environment, here we conduct a radiation analysis for PolarBeeSail, which will have a polar orbit, using the models in SPENVIS. As a result of the analysis we recommend an applicable thickness of aluminium to be used with PolarBeeSail. Keywords—solar sail, space environment, magnetosphere, polar cusp, CubeSat, SPENVIS, radiation analysis I. INTRODUCTION CubeSat technologies are highly advanced such that the science-targeted missions become rapidly increased to be used in addressing the variety of potential problems in space environment. The propellant usage in a satellite limits the size of the payload that includes the scientific instruments. The solar sailing gives an opportunity for scientists to improve this limitation. Since the sail acceleration is provided by the solar radiation pressure, it does not need propellant. Absence of propellant tanks allows more scientific instrument placed in the satellite for a detailed study of the environment. The polar regions of the magnetosphere are characterized by low magnetic fields and plasma mixed from the solar wind and magnetosphere, and it is composed of highly energetic particles. The region is difficult to study for satellites owing to the risks resulting from the energetic particles. By taking the advantage of the solar sail, we plan to build a polar orbiting PolarBeeSail (PBS) satellite to study the polar magnetosphere extending from the magnetopause into the magnetosheath. The orbit of the PBS is designed to be elliptical with a perigee of 4 Re in the southern hemisphere and an apogee with 20 Re in the northern hemisphere with 80º inclination. Owing to its orbit, PBS will move through different parts of polar magnetospheric environment such as polar cusps, magnetopause, and magnetosheath during its mission. This will enable to study the structure and properties of these regions in detail. Our study will focus on the effects of the space weather events on the polar orbiting satellites. For plasma measurements, we plan to design and built a plasma analyzer in Istanbul Technical University’s Space Weather Laboratory (SWL). Along its orbit, PBS will travel through radiation belts that are populated by the high energetic particles from the Sun and cosmic rays and pass the magnetopause and move farther in the magnetosheath. Therefore, for a successful mission, it is important to test the spacecraft before its launch on ground. Tests for the radiation dose effects for PBS are carried out using SPENVIS tools and are the subject of our presentation. II. POLARBEESAIL A. Solar Sailing Solar sail propulsion is obtained from the Solar Radiation Pressure (SRP) that is applied by the absorbed and reflected photons on the sail area. By transferring the SRP momentum on the sail, which is made of strong and lightweight membranes, the spacecraft gains the necessary propulsion for both attitude control and orbit manoeuvre that is called “solar sailing”. When the object reflects the photon instead of just absorbing in, the momentum obtained becomes twice as the photon’s initial momentum. The parameters affecting the SRP are briefly explained as follows:  When the distance from the Sun increases, SRP and therefore, the thrust gained decreases.  The sail area is proportional with the SRP.  The position of the sail with respect to the incoming direction of the photons is a very important factor for the propulsion gained. The manoeuvrability of the sailcraft relies on the thrust component perpendicular to the Sun-sailcraft line. Sailcraft could gain orbital angular momentum and spiral outward (away from the Sun) or lose orbital angular momentum and spiral inward (toward the Sun) when the incoming photon is not perpendicular to the sail system [1].  The optical properties of the sail material are also very important parameter on the propulsion obtained. To simplify the situation, for PBS design, we assumed there is a perfect reflection and the sail position is arranged by the This project work is supported by Turkish Scientific and Technological Council (TÜBİTAK) that is called “Plasma measurements in the magnetospheric polar cap using CubeSatSail for space weather studies”.