They have outlined a plan for solar powered space defences which could vaporise an asteroid as big as the one which flew past Earth last week in 60 minutes.
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.
Researchers Philip M Lubin from the University of California, Santa Barbara and Gary B Hughes from California Polytechnic State University 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.
"We need to be proactive rather than reactive in dealing with threats. Duck and cover is not an option. We can actually do something about it and it's credible to do something," said Lubin, who began work on DE-STAR a year ago.
DE-STAR is designed to harness some of the power of the Sun and convert it into a massive phased array of laser beams that can destroy, or evaporate, asteroids posing a potential threat to Earth.
It is equally capable of changing an asteroid's orbit - deflecting it away from Earth, or into the Sun - and may also prove to be a valuable tool for assessing an asteroid's composition, enabling lucrative, rare-element mining.
"This system is not some far-out idea from Star Trek," Hughes said in a statement.
"All the components of this system pretty much exist today. Maybe not quite at the scale that we'd need - scaling up would be the challenge - but the basic elements are all there and ready to go.
"We just need to put them into a larger system to be effective, and once the system is there, it can do so many things," Hughes said in a statement.
The same system has a number of other uses, including aiding in planetary exploration.
Lubin and Hughes calculated the requirements and possibilities for DE-STAR systems of several sizes, ranging from a desktop device to one measuring 10 kilometers in diameter. Larger systems were also considered. The larger the system, the greater its capabilities.
For instance, DE-STAR 2 - at 100 meters in diameter, about the size of the International Space Station - "could start nudging comets or asteroids out of their orbits," Hughes said.
But DE-STAR 4 - at 10 kilometres in diameter, about 100 times the size of the ISS - could deliver 1.4 megatons of energy per day to its target, said Lubin, obliterating an asteroid 500 meters across in one year.