Invaders Of Mars

Wikipedia has an interesting little article about the origins of the word ‘sensawunda.’ The word is, of course, a contraction of the phrase ‘sense of wonder,’ and the article’s header defines it as ‘…an intellectual and emotional state frequently invoked in discussions of science fiction. It is an emotional reaction to the reader suddenly confronting, understanding, or seeing a concept anew in the context of new information.’

Which is fair enough. Personally, my own definition of sensawunda would be that it’s the feeling you get when you see or discover something utterly wonderful about the world around you. One of my most memorable sensawunda moments was hearing the sound of the wind recorded by the Huygens probe as it descended through the atmosphere of Titan, but I feel the same way about the mind-bending implications of the Holographic Principle and watching our cats dreaming. It’s a very personal thing.

I have an enormous feeling of sensawunda about Curiosity, the NASA probe currently trundling across a rock-strewn landscape on Mars. We’ve littered the Solar System with so many probes since the heady days of Viking that there’s almost a ‘so-what?’ feeling about it, but Curiosity is a marvel.

For a start, it’s a miracle it’s there at all, let alone mostly fully-functional. Curiosity is about nine and a half feet long by nine wide and about seven feet tall – it’s commonly described as being ‘the size of a car’ – and weighs getting on for a ton. It’s carrying about 180 pounds of scientific instruments and is by far the most sophisticated thing we’ve chucked at another planet. Certainly it’s the largest. It cost two and a half billion dollars, which is a lot of money in anyone’s language.

It was launched in November last year, and there was no guarantee it would even reach Mars.  According to this article in Wired, more than half of the missions to Mars have failed for some reason. And there’s only a thirty percent success rate in actually getting anything onto the surface in some kind of usable state. The loss of Beagle 2 back in 2003 was presented as a bit of an embarrassment, but in fact it was not an unusual occurrence. It’s more unusual for these things to succeed.

In the case of Curiosity, the odds were stacked even more greatly against success. Assuming the thing didn’t blow up during launch, and assuming nothing went wrong during the cruise phase of the trip, and assuming it made a successful insertion into orbit around Mars, there was the tricky proposition of actually getting it onto the surface in one piece.

NASA has, in the past, landed kit on Mars in some pretty wacky ways. Curiosity’s little cousins, the rovers Spirit and Opportunity, arrived coccooned in airbags and basically bounced across the surface of the planet until coming to a halt and deploying themselves. This would not have worked with Curiosity, which is a lot heavier, so the engineers came up with something rather remarkable and definitely risky.

Curiosity travelled to Mars attached to a ‘descent stage’ – basically a big chandelier of rockets. After using parachutes to slow its descent, at around a mile up and still falling at about two hundred miles an hour, the thing jettisoned various bits and pieces and the descent stage fired its rockets to slow the assembly even further until it was hovering. It then lowered the rover on three nylon lines until it touched down gently on the surface. Then the lines were cut, and the descent stage flew off to one side and crash-landed.

All of which sounds pretty spectacular and I would have given quite a lot to have been standing on the surface watching, but what was even more amazing – to me at least – is that it was completely automatic. At the moment, it takes fourteen minutes for a radio signal to reach Mars, making it impossible to control the landing from Earth – by the time an operator learned of a problem and tried to correct it, Curiosity would have been a $2.5 billion debris trail for almost half an hour. So it was all done by onboard computer, and I think that is by god amazing. NASA obviously performed exhaustive tests and simulations, but this kind of ‘skycrane’ manouvre has never been used on a mission before and the list of things that could have gone pear-shaped with it are endless and probably gave the people in Mission Control a number of sleepless nights. They did, with admirable restraint, dub this final phase of Curiosity’s journey to Mars ‘The Seven Minutes Of Terror.’ In their shoes I would have called it ‘The Seven Minutes Of Soiling Our Underwear While Screaming Helplessly.’

Curiosity landed in Gale Crater, a meteor impact crater with a three-and-a-half-mile-high mountain in the middle. After travelling 350 million miles, it missed its planned target point by just a mile and a half, which I think is quite incredible. A bit like bullseyeing a grape with an air rifle from a distance of half a mile or so. It arrived more or less in perfect working order and now it’s rolling patiently about analysing rocks and taking magnificent pictures. If we ever get bored of these pictures – and I could quite happily sit and look at them all day – we should remember what it took to get them.

And that, in part, is what I mean when I say ‘sensawunda.’


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