Can Earth-Threatening Iron Asteroids Be Diverted Using Terrestrial Lasers?

G. L. Matloff. (2021), JBIS, 74, pp.2-5

Refcode: 2021.74.2

Abstract:

Near Earth Objects (NEOs) occasionally impact the Earth with devastating consequences for the biosphere. There may be 18,000 NEOs with radii greater than 100 m. This paper evaluates the possibility of diverting a threatening NEO using the 50-70 GW laser array proposed for Project Starshot by the reaction force of the jet raised by the laser hotspot on the NEO. A 100 m pure iron NEO is considered, with the laser operated during a 1-year warning time at a starting Earth-NEO separation of about 107 km. A very conservative thermodynamic model is used in which jet velocity is limited by sound speed in the hotspot with no ablation or desorption. It is shown that an Earth impact can be converted into a near miss using a fraction (<20%) of laser power applied for ~10% of the warning time duration. Because the Starshot laser array is proposed to be mounted atop a southern hemisphere mountain, a duplicate array in the northern hemisphere is necessary for full sky coverage. These results validate the conclusions of a 2013 Earth defence paper by Lubin et al.