Nuclear-power-plant operators use similar technology as a kind of fuel gauge for the uranium-oxide fuel rods in commercial nuclear reactors. The rods' composition changes as they are used up, she explains. Archaeologists have used the technique to identify the composition of artifacts. Scrap-metal recyclers use it to identify the types of steel they receive. And security specialists are eying it as a tool that could help screen for explosives at airports and along US borders.
The technology was adapted for space missions by a team led by Los Alamos National Laboratory geochemist Roger Wiens, ChemCam's lead scientist. The Mars Science Laboratory's mission marks the instrument's maiden flight.
On Mars, ChemCam represents the Annie Oakley among the rover's science packages. It can place its powerful laser beam on a spot the size of a period on a printed page at 23 feet – farther in the lab, Dr. Dyar acknowledges, but for Mars, 23 feet will do.
The beam plants 1-million-watt pulses on the spot for about five-billionths of a second each, heating the rock or dust it encounters to more than 3,500 degrees Fahrenheit, vaporizing the material.
From a hypothetical Martian's standpoint, the beam's encounter with rock looks like the spark from a butane barbecue lighter. But the spectrum from that tiny bit of light carries an enormous amount of information about the types of atoms present in the material vaporized and their relative abundance.
Indeed, the device is the only one aboard the rover that can identify atoms across the entire periodic table of elements, giving researchers more opportunity to test the makeup of rock types they didn't anticipate finding.
By comparing the results ChemCam delivers from Mars with the spectra of up to 2,000 so-called calibration samples on Earth, researchers will be able to identify the rocks and minerals ChemCam zaps.
And if the rock of interest is covered with dust? No worries. A series of pulses from ChemCam's laser becomes the high-tech whisk broom that exposes the rock surface scientists really want to analyze.