There are big rocks waiting to fall onto the Earth one day. Not too often but they are there. As an asteroid roughly half as large as a football field — and with energy equal to a large hydrogen bomb — readies for a fly-by of Earth on Friday, two California scientists are unveiling their proposal for a system that could eliminate a threat of this size in an hour. The same system could destroy asteroids 10 times larger than the one known as 2012 DA14 in about a year, with evaporation starting at a distance as far away as the Sun. UC Santa Barbara physicist and professor Philip M. Lubin, and Gary B. Hughes, a researcher and professor from California Polytechnic State University, San Luis Obispo, conceived DE-STAR, or Directed Energy Solar Targeting of Asteroids an exploRation, as a realistic means of mitigating potential threats posed to the Earth by asteroids and comets.