IonSat: challenging the atmospheric drag with a 6U nanosatellite
Résumé
Herein, we present a feasibility study and a mission design for a 6U CubeSat propelled by an iodine NPT-30i miniaturized thruster from the company ThrustMe, to be ready for launch in the early 2020s. The project is led by École polytechnique, Palaiseau, France and supported by the French space agency CNES. The phase A study shows that the stand-alone propulsion system can be embedded in a 6U CubeSat and be used in the frame of a coherent mission over more than a year, under the condition of integrating a low-requirements payload, mainly in terms of volume. Deployable solar generators, aerobraking strategies and large battery capacities allow the satellite to perform orbit changes and station-keeping at 300km from any orbit inclination. This mission aims to demonstrate a long-duration station-keeping at low altitude and to assess the suitability of electric propulsion devices for tightly constrained missions such as student CubeSats. As part of the phase A study, the design of an attitude control system relevant to orbit changes is presented, as well as a first thermal analysis of a 6U CubeSat able to generate more than 50W of power. The mission analysis is also explicated: it led to the unusual choice of a spacecraft able to tackle most orbits, at the cost of an adaptation of the mission plan. The general resulting structure and subsystems integration to comply with such constraints is also presented. It is designed to compromise between aerodynamics and total power supply with deployable solar panels and a displaced centre of mass. This feasibility study tends to show that propulsion for SmallSats is available and has reached milestones in terms of costs and ease of integration that make it compatible with university projects. It is also shown that a 6U CubeSat can today be suitable for a mission needing an electric power subsystem, providing the payload does not have demanding power or volume requirements.