NASA's Mars rover, Curiosity, is armed with a laser to zap rocks, not Martians. The laser can vaporize rocks at a distance of 23 feet.
But there are no plans for Curiosity to zap Martians.
This cool little laser – and it is tiny – is designed to vaporize a pin-head sized area of Martian rock. The laser heats up the rock, and turns it into a glowing ionized gas. It's part of an instrument on the rover Curiosity known as the "ChemCam." The ChemCam observes the flash of vaporized rock and analyzes the spectrum of light to identify the chemical elements in the rock. The laser has a range of about 23 feet.
Here's how NASA describes the process:
"The pinhead-size spot hit by ChemCam's laser gets as much power focused on it as a million light bulbs, for five one-billionths of a second. Light from the resulting flash comes back to ChemCam through the instrument's telescope, mounted beside the laser high on the rover's camera mast. The telescope directs the light down an optical fiber to three spectrometers inside the rover. The spectrometers record intensity at 6,144 different wavelengths of ultraviolet, visible and infrared light. Different chemical elements in the target emit light at different wavelengths."
If the ChemCam analysis proves interesting, the Curiosity rover can move in and drill or scoop up an actual sample of the rock. The pulse laser can also be used to "dust off" an interesting rock formation with a series of short bursts.