Speaking of lasers,  Philip Lubin, a professor of experimental cosmology at UC Santa Barbara, gives a SETI Institute lecture on the DE-STAR project to design a system to protect earth from comet and asteroid collisions : Is Planetary Defense Feasible – DE-STAR: A Planetary Defense and Exploration System –

Dr. Lubin will discuss how his team has proposed an orbital planetary defense system that is capable of beamed power allowing a number of directed energy (DE) possibilities including planetary defense, propulsion allowing relativistic probes and interstellar communications using existing technologies. Recent developments in photonics allow such a system whereas even a decade ago it would have been simply science fiction.