The system known as DE-STAR - or Directed Energy System for Targeting of Asteroids and exploRation - has been a concept for years but tests show it could now be a viable option.
Physicists from the University of California say an unmanned space-travelling DE-STAR craft could use lasers to heat up asteroids which are heading towards Earth.
When the asteroid begins ejecting material as a result, the reactionary force will move it onto a different path.
DE-STAR would operate deep in space, engaging asteroids up to two millions mile away.
A craft with a 100-metre laser array, for example, could divert asteroids of a similar diameter.
The technique was tested by directing a laser onto basalt - which has a composition similar to asteroids.
When it began to glow white-hot, material fell away from the sample creating a kind of rocket engine, where the heated side of material tried to propel it in the other direction.
In space, this propellant would be enough to alter the course of an asteroid.
Travis Brashears, one of the team members working on the project, said: "What happens is a process called sublimation or vaporisation, which turns a solid or liquid into a gas.
"That gas causes a plume cloud - mass ejection - which generates an opposite and equal reaction or thrust, and that`s what we measure."
They also simulated a spinning asteroid, managing to slow the rotation using a combination of powerful magnets and the laser technique.
The theory has been around for several years, but a paper published in Earth and Planetary Astrophysics suggests it could now be a viable option.
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