• E-sail
• LEO space environment
• orbital simulator
• Plasma Brake
• space debris de-orbiting

In this work the problem of Plasma Brake has been characterised from an orbital flight mechanics point of view. Plasma Brake thrusters are essentially braking devices which provide active and controllable spacecraft acceleration by means of electrostatically charged tethers interacting with the environmental plasma.
A simplified and approximated Plasma Brake model has been created in order to reduce computational times and keep acceptable errors for preliminary mission design analyses. The model has been specifically adapted to circular, Low Earth Orbits (LEOs) and implemented into an orbital simulator written in Matlab® code. The main task of the orbital simulator is the determination of the de-orbiting time of a spacecraft, given initial calendar date, its initial orbital parameters (or equivalently position and velocity vectors), and the tethers system characteristics. The simulator has been validated by comparison with a reference ISS de-orbiting profile and the approximated Plasma Brake model errors have been estimated.
The local optimal control laws have been also identified for the minimum de-orbiting time between two reference altitudes and for a reference spacecraft.
A sensitivity study has been conducted with respect to the reference configuration and some peculiarities of the physics involved in the Plasma Brake problem have been identified, including analogies with the atmospheric drag.
The complete Plasma Brake model has then been implemented into the orbital simulator, extending the analysis to non-circular orbits and in particular to interplanetary re-entry trajectories. In this scenario, a very basic feasibility study of a “plasma-capture” mission has been performed, considering an interplanetary mission re-entering from the planet Mars (with the hypotheses of circular and coplanar planetary orbits, Hohmann transfer, and hyperbolic re-entry).
Finally, Plasma Brake performances were evaluated and compared with different propulsive technologies, outlining advantages in using Plasma Brake thrusters instead of the conventional and already space-qualified ones.