Orbital Simulations on Deflecting Near-Earth Objects by Directed Energy

TL;DR

This paper uses orbital simulations to compare the effectiveness of stand-off and stand-on directed energy systems in deflecting Near-Earth Objects via laser ablation, highlighting key parameters influencing deflection success.

Contribution

It introduces a comprehensive simulation framework for assessing laser-based NEO deflection systems, analyzing how thrust, duration, and direction affect deflection outcomes.

Findings

Deflection distance scales with thrust magnitude and square of ablation duration.

Optimal thrust direction varies with laser activity duration.

A 20 kW stand-on system can deflect a 325 m asteroid by 2 Earth radii if started 15 years in advance.

Abstract

Laser ablation of a Near-Earth Object (NEO) on a collision course with Earth produces a cloud of ejecta which exerts a thrust on the NEO, deflecting it from its original trajectory. Ablation may be performed from afar by illuminating an Earth-targeting asteroid or comet with a stand-off "DE- STAR" system consisting of a large phased-array laser in Earth orbit. Alternatively, a much smaller stand-on "DE-STARLITE" system may travel alongside the target, slowly deflecting it from nearby over a long period. This paper presents orbital simulations comparing the effectiveness of both systems across a range of laser and NEO parameters. Simulated parameters include magnitude, duration and, for the stand-on system, direction of the thrust, as well as the type, size and orbital characteristics of the target NEO. These simulations indicate that deflection distance is approximately proportional to the magnitude of thrust and to the square of the duration of ablation, and is inversely proportional to the mass. Furthermore, deflection distance shows strong dependence on thrust direction with the optimal direction of thrust varying with the duration of laser activity. As one example, consider a typical 325 m asteroid: beginning 15 yr in advance, just 2 N of thrust from a ~20 kW stand-on DE-STARLITE system is sufficient to deflect the asteroid by 2 R_e. Numerous scenarios are discussed as is a practical implementation of such a system consistent with current launch vehicle capabilities.