Duration: 6 months
Deorbiting with high reliability is hard, especially with CubeSats. This is because traditional methods require most of the satellite subsystems to be functional. Most CubeSats cannot demonstrate their reliability, preventing them from being flown if regulations require a specific reliability level. Reaching the 99% reliability target defined in the ESA Zero Debris Charter (ZDC) is practically impossible. Additionally, the satellites needing to deorbit while still functional removes the possibility for mission extensions.
Our solution, Charon, is a fully independent deorbiting system in a 1U form factor. It functions as a “watchdog”: it will automatically deploy and deorbit the satellite if it does not receive a repeating confirmation from the satellite telling it is still alive. It will have a relatively long timer, such as 2 months, after which it will start deorbiting. The satellite can reset that timer by sending it a reset command, or “petting” the watchdog, which it does periodically.
The deorbiting will be performed by the Plasma Brake, the electrostatic tether that utilizes ionospheric plasma to create a Coulomb Drag force. It allows up to 1000 km orbits, while not requiring exact attitude control. The system average power consumption is ~0.5 W, which can be generated by a small independent solar panel on the subsystem. The tether deployment is achieved by spinning up the satellite with a small thruster unit (such as the 0.04 U ARM-C by Aurora Propulsion Technologies). The spinning also ensures the solar panels are not eclipsed for long durations.
This system is unique in that it allows safe deorbiting even if the satellite is dead on arrival, which is unfortunately common for CubeSats. It also greatly reduces the amount of paperwork required for acquiring launch permits, as the reliability of the satellite does not need to be analyzed. It can be also used as a secondary redundant deorbiting method, allowing the ZDC 99% reliability figure to be reached.
