Preliminary Design of the Propulsion Subsystem for the European Advanced Reusable Satellite (EARS)

The European Advanced Reusable Satellite (EARS) is a European Commission funded program that aims at designing a reusable microsat to deliver commercial, scientific and institutional payloads to LEO and retrieving them back safely on Earth. The program seeks to develop the key enabling technologies for the foreseen mission. In this frame, T4i is designing the propulsion subsystem for the satellite and is developing the HTP and propane fed bipropellant thruster. The propulsion subsystem is responsible for delivering a precise de-orbit burn using 4 engines that rely on differential steering to keep the thrust vector aligned with the velocity vector. Differential steering is obtained through the thrusters’ pulsed mode where their nominal bi-propellant working mode is switched temporarily to a mono-propellant one by shutting off the fuel feeding valve. While this procedure slightly reduces the average specific impulse delivered by the platform, it allows for a simple and robust two axis control of the spacecraft during firing. A third controlling element, a propane cold gas reaction control system, was identified as the best solution for controlling rotations around the roll axis.