Dynamics of tethered asteroid systems to support planetary defense

Every year near-Earth object (NEO) surveys discover hundreds of new asteroids, including the potentially hazardous asteroids (PHA). The possibility of impact with the Earth is one of the main motivations to track and study these objects. This paper presents a tether assisted methodology to deflect a PHA by connecting a smaller asteroid, altering the center of mass of the system, and consequently, moving the PHA to a safer orbit. Some of the advantages of this method are that it does not result in fragmentation, which could lead to another problem, and also the flexibility to change the configuration of the system to optimize the deflection according to the warning time. The dynamics of the PHA-tether-asteroid system is analyzed, and the amount of orbit change is determined for several initial conditions. Only motion in the plane of the orbit of the PHA around the Sun is considered, thus the PHA chosen for the simulations has low orbit inclination. Analysis of the dynamics of the system shows that the method is feasible for planetary defense.