An innovative concept for passive stability is employed for QARMAN based on the aerodynamic forces. Typical satellites are using either passive control via permanent magnets which aligns itself with the magnetic field lines or active control elements like reaction wheels and magnetorquers. These active mechanisms have major drawbacks due to the power consumption of the system during actuation which could be too demanding for small scale satellites like CubeSats. Furthermore they have a strong impact on the mass and volume budget. However the main issue preventing their usage on QARMAN is that the disturbance forces below 150km of altitude are too large to be counteracting with a reasonable sized systems.
Therefore QARMAN employs an Aerodynamic Stability and De-orbiting System which relies completely on the aerodynamic forces acting on the satellite. This passive system has the advantages of no power consumption after deployment and that the restraining forces are increasing with decreasing altitude similar to the perturbations. This makes the system ideally suitable for the QARMAN mission allowing the satellite to perform the complete re-entry with a controlled attitude.
A trade-off campaign was performed to identify the best solution of the AeroSDS used on QARMAN keeping in mind the different requirements on the system like compatibility which orbital and re-entry phase, a reliable and simplified system, the interoperability with other systems like power generation and the target lifetime in orbit from deployment altitude. As an example the effect of different systems on the lifetime is shown in the following picture and gives evidence of the customable design to satisfy the mission needs for faster or slower de-orbiting.
A design based on four ceramic panels with a length of approximately 30cm and inclination of 15° with respect to the longitudinal axis was chosen due to the good performance in orbit and during the re-entry mission. To ensure a smooth outer surface and transition without gaps from the sidewalls to the panels, a deployment based on two simultaneous motions (rotational and translational) was implemented for the AeroSDS. Sufficient generated power during the first phases in orbit is ensured by the integration of solar cells on both sides of the deployable panels.