On Mars this weekend, the Curiosity rover gets a first chance to try out its ChemCam (Chemistry and Camera) imaging system, which includes a powerful laser – over a period of 10 seconds or so, it will fire off about 30 shots at a designated sitting target, which is located three metres away. This target has been given the imaginative name of N165, and is an otherwise rather unexceptional, small, roughly triangular-looking Martian rock, about 7.5 centimetres wide. The flashes of light generated by the mini laser strikes will then be analysed by Curiosity’s spectrometer, to see what N165 is composed of.
The laser is, of course, a very familiar device, and ubiquitous these days. The first one was built in the 1960s, but before then, in the 1950s, scientists had already developed its older cousin the maser – from “Microwave Amplification by Stimulated Emission of Radiation” – which amplifies microwaves rather than visible light (an early term for the laser was “optical maser”, in fact.)
One of the obvious applications of course, for this emerging technology was as a beam weapon, but – perhaps fortunately – this has not really happened yet, outside the realm of SF and James Bond. This idea can be traced back to the fiction of H.G. Wells, whose Martians wielded a horribly effective Heat Ray after they landed in Surrey, in his 1898 novel The War of the Worlds. Here is the moment when a group of men approach the landing site, hoping to communicate with the visitors from another world:
Beyond the pit stood the little wedge of people with the white flag at its apex, arrested by these phenomena, a little knot of small vertical black shapes upon the black ground. As the green smoke arose, their faces flashed out pallid green, and faded again as it vanished. Then slowly the hissing passed into a humming, into a long, loud, droning noise. Slowly a humped shape rose out of the pit, and the ghost of a beam of light seemed to flicker out from it.
Forthwith flashes of actual flame, a bright glare leaping from one to another, sprang from the scattered group of men. It was as if some invisible jet impinged upon them and flashed into white flame. It was as if each man were suddenly and momentarily turned to fire.
Then, by the light of their own destruction, I saw them staggering and falling, and their supporters turning to run.
If there is microbial life on Mars, and if a deputation of tiny Martians have assembled today on N165, preparing to communicate with this giant visitor from another world, it would be a very odd and ironic – if highly unlikely – twist on the classic tale.
Well, the laser firing seems to have gone well (hopefully with no microscopic Martian pacifists being killed), and now Curiosity has gone for its first drive. We can see tyre tracks!