NASA's Mars Science Laboratory and ChemCam
NASA's Mars Science Laboratory and ChemCam

Space exploration has caught up with science fiction (again): we have deployed laser-armed nuclear-powered robot on Mars, and nearly two weeks after landing, NASA’s Mars Science Laboratory, the rover Curiosity, has fired that weapon on a Martian…rock.

Certain images from sci-fi classics come to mind. Remember, “The Day the Earth Stood Still” when Gort, the golem-like space-cop-bot, went about melting soldiers’ rifles with an incinerating ray? Recall how the Robinsons became “lost in space” when their reprogrammed automaton when berserk with its electric bolts? And who can forget when dear old R2D2 finally let slip that he/she/it is armed and dangerous when he/she/it zapped the little gremlin from the planet FrankOz? This is the droid you want…Ah, good times.

The rover Curiosity is equipped with ten different scientific experiments, perhaps the flashiest one being a spectrometer. A spectrometer sorts and analyzes the wavelengths (colors) of light emitted by an object: the light’s spectrum. Every chemical element and compound shines a unique spectrum, so sorting out the different wavelengths present reveals the source’s composition.

Spectrometers are a powerful tool for astronomers and geologists alike. We first learned that stars are composed mostly of hydrogen and helium through spectroscopic measurements, and in the same way we also detected the presence of dozens of other chemicals on the sun. (As an aside, helium was named for the sun—Helios, in Greek—because it was detected there by spectrometers before it was discovered on Earth.)

But in an environment like Mars, where the visible light shining from the rocks and soil of the landscape is merely reflected sunlight, using a spectrometer doesn’t tell you much about the composition of the rocks and soil! That’s where the dangerous, high-powered laser comes in. By firing the laser on a rock or a spot of soil, a small bit of it is vaporized and glows with its own light. Then, Curiosity’s spectrometer can do its work and analyze the emitted light.

And that’s just what it did, for the first time, on August 19, firing its laser multiple times on a spot on a nearby rock and sending the resulting spectrum back to Earth.

This first shot fired on Mars made for a nice harvest of chemistry: titanium, manganese, calcium, iron, aluminum, silicon, carbon and hydrogen—no big surprises; we already knew that Mars isn’t composed of unobtanium, but the same chemicals and minerals that make up the Earth. The sample fired upon turns out to be a form of basalt, a volcanic rock common on Mars.

As Curiosity makes its way up the slopes of sediments that make up Mt. Sharp, the tall mountain in the center of Gale Crater, the rover’s landing site, it will use the laser and spectrometer, along with its array of other chemistry experiments, to build up a picture of Mars’ geologic history, sorting out what minerals were most abundant at what times in the past. The aim is to build a clear timeline of Mars’ transformation from its once warmer, wetter stages to its present state as a cold, dry desert.

It’s exciting to think that, as Curiosity rolls up the mountain, moving from the most ancient layers of sediment upward through the eons toward today’s Mars, its wheels will be treading the materials left behind by Mars’ past environments and climates.

And, if life ever arose on the Red Planet and left behind telltale chemicals, those wheels will make contact with Martians! (Sort of.) Imagine the light that laser will shed on our perception of Mars once and if Curiosity delivers the news that, yes, there is (or was) life out there.


Ben Burress

Benjamin Burress has been a staff astronomer at Chabot Space & Science Center since July 1999. He graduated from Sonoma State University in 1985 with a bachelor’s degree in physics (and minor in astronomy), after which he signed on for a two-year stint in the Peace Corps, where he taught physics and mathematics in the African nation of Cameroon. From 1989-96 he served on the crew of NASA’s Kuiper Airborne Observatory at Ames Research Center in Mountain View, CA. From 1996-99, he was Head Observer at the Naval Prototype Optical Interferometer program at Lowell Observatory in Flagstaff, AZ. Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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