Deviation of Earth Threatening Asteroids Using Tether and Ballast

Abstract

The effects of the collision of a Near-Earth-Object(NEO) with the Earth could be catastrophic on a local, regional or global scale depending on the size of the NEO. Therefore, there is considerable interest in determining ways to mitigate the threat posed by these objects. This dissertation presents a method utilizing a tethered ballast mass for altering the trajectory of a NEO with an Earth-intersecting orbit so that it avoids hitting the Earth. The method is simulated using four different methods. The first method assumes a rigid massless tether. Using this method, a parametric study was conducted to determine the effectiveness of the technique over a wide parametric space. Specifically, this study provided results in terms of deviation rates over the parametric space. After this, the massless inelastic method was used to study actual miss distances assuming the asteroid was on a collision course with the Earth. After this, a study was conducted, using the massless, inelastic model, in which the mass of the ballast was made constant, in order to determine the minimum tether length required to divert asteroids simulated based on actual asteroids from NASA's potentially hazardous asteroid (PHA) database, again assuming a massless inelastic tether. Finally, it was desired to determine how relaxing the constraints of the massless inelastic model would affect system performance. Therefore, three more models were introduced: massive inelastic, massless elastic, and massive elastic. Using these models, a study was performed to explore the effects of the changed model on system performance and to compare the results in terms of deviation, with those of the massless inelastic model. This was desired because the numerical cost of the new models was much higher than that of the massless inelastic model, so rather than conduct the study over a much larger parametric space, a smaller space was chosen, so that the results could be compared.