American researchers believe laser beam could be used to deflect space rocks on collision course with planet Earth
It sounds like a weapon straight out of Star Wars. Imagine the Death Star’s superlaser used not to destroy worlds but to protect our own from approaching asteroids.
That is the concept being developed by American researchers who believe they have found a way to use a high-power laser beam to deflect space rocks that are on course to hit Earth.
The idea has been around for years but the team at the University of California say laboratory tests show their De-Star – or Directed Energy System for Targeting of Asteroids and exploRation – could actually work.
They envisage putting an unmanned De-Star craft in orbit. At the first sign of a impending disaster it would target the asteroid with a high-energy laser, causing part of the rock to vaporise in a process known as sublimation.
That ejection of gas would then create sufficient force to alter the course of the rock.
Qicheng Zhang of the University of California, Santa Barbara, one of the authors of the project, told Astrowatch.net: “Generally speaking, the technology is available today.
“The main challenge with building a full De-Star is the necessary scale to be effective.”
They have tested the technique on earth, by blasting a piece of basalt – an igneous rock similar in composition to some asteroids.
The technique was tested by directing a laser onto basalt – which has a composition similar to asteroids.
They found that when it glowed white-hot, it began to lose mass.
Travis Brashears, a student who has worked with the group, said last year: “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.”
The managed to use the effect to slow and the reverse the rotation of a spinning piece of basalt.
The forces involved mean the team needs plenty of warning of impending doom. They estimate they could use a 10 kW laser – less powerful than some used by the US military, for example – to deflect a 100m wide asteroid over a period of 30 years.
At the same time, they are working on a smaller version that could fly alongside asteroids, acting as a last line of defence if there was less of a warning.