In The War Of The Worlds, H G Wells’ scifi classic of the 19th century, machines sent by Martians brought terror and destruction to Earth by attacking with deadly heat-rays. But in a reversal of roles, Earthlings have fired the first shots in any interplanetary conflict by blasting Mars with a powerful laser beam.



This real-life ray-gun, used for the first time yesterday by NASA’s Curiosity rover, two weeks after its spectacular landing on the Red Planet, is not, of course, a weapon of aggression.

Planetary scientists designed it as a quick and effective method of discovering just what individual stones on Mars are made of. NASA’s last robotic rovers, Opportunity and Spirit, had to do this a long-winded way, first by brushing dust from a rock and then by grinding away at it and analysing the bits.

By contrast, Curiosity does it in a flash. Or 30 flashes to be absolutely precise. In a first test on Mars of the probe’s Chemcam experiment, it fired 30 pulses of a laser beam at a fist-sized rock labelled N165 and dubbed Coronation. The blast, over a ten-second period, delivered more than a million watts of power for five one-billionths of a second with each pulse.

The assault by Curiosity, or Mars Science Laboratory to give it its official name, vaporised a tiny patch of the rock, creating a hot ionised gas, or plasma, that the robot could analyse with three spectrometers on board to find what it is made of.

They will need to know this as they explore Curiosity’s landing site, Gale Crater, over the next two years to discover the environment in which that landscape formed. Finding out the composition of the rocks will confirm whether they formed in the presence of vast amounts of water, which will give more clues as to whether Mars was ever habitable. ChemCam will also be able to detect the chemistry that life needs to exist, including oxygen, nitrogen and carbon.

Apart from the laser, another part of the ChemCam experiment is the highest-resolution camera ever sent to the martian surface. That will examine the rocks to allow experts at mission control back at NASA’s Jet Propulsion Laboratory (JPL) in California to see how they may have been altered by the presence of water.

ChemCam is an international experiment built with the aid of scientists in France. Its powerful imaging sensor was built by a British company, e2v of Chelmsford, Essex. The scientists were thrilled with the result of their “target practice”.



ChemCam Deputy Project Scientist Sylvestre Maurice of the Institut de Recherche en Astrophysique et Planetologie (IRAP) at Toulouse, France, said: “It’s surprising that the data are even better than we ever had during tests on Earth, in signal-to-noise ratio. It’s so rich, we can expect great science from investigating what might be thousands of targets with ChemCam in the next two years.”

ChemCam Principal Investigator Roger Wiens of Los Alamos National Laboratory, New Mexico, said: “We got a great spectrum of Coronation – lots of signal. Our team is both thrilled and working hard, looking at the results. After eight years building the instrument, it’s payoff time!”

It is not the first time that a NASA space mission has launched an “attack” on another world. In October 2009, the orbiting probe LCROSS and its rocket booster were deliberately crashed into a crater near the Moon’s south pole in a successful bid to detect water ice.

And in July 2005, a probe called Deep Impact fired a “smart bomb” at Comet Temple 1, causing an enormous and brilliant explosion, to help scientists discover what lies inside it.

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