In the Ray Bradbury short story A Sound of Thunder, a time traveller goes back to the late Cretaceous era, because who doesn't want to see a live dinosaur?
But when finally confronted by a Tyrannosaurus rex, he panics and runs off a dedicated path into the forest, accidentally stepping on a butterfly – hardly the most egregious instance of environmental damage, right?
Wrong, because when the time traveller returns to 2055, the world has changed in subtle but significant ways – people's behaviour is different, words have changed, and a fascist president sits in the White House.
Bradbury’s tale is the perfect illustration of the risk of contamination. It’s not actually the origin of the term “the butterfly effect”, but it shows how altering an environment or events in the smallest way can lead to an utterly unpredictable chain of events.
Running water
Which brings us to Monday’s slightly giddy announcement by
Nasa
that they had discovered the clearest evidence yet of liquid water on Mars.
The evidence comes in the form of “recurring slope lineae”, long, dark stains that can be observed on slopes and canyon walls around the planet’s equator and which appear to be the result of briny water flowing downhill during the summer months and leaving marks on the soil after drying in the autumn.
This is not the first clue that there is still some water on the famously arid planet, but it seems to be the most convincing, leading to all sorts of speculation that there may be life on Mars, or that it might one day sustain human colonies.
But before the world’s space agencies start packing their bags, there’s a snag – back in 1967, the UN passed something called the Outer Space Treaty, which forms the basis for international space law.
It’s one of those admirably utopian documents, calling for all sorts of international co-operation when it comes to space exploration, especially considering it was signed at the height of the Cold War.
The treaty covers a lot of ground, but one of its provisions ensures countries “conduct exploration of [planets] so as to avoid their harmful contamination and also adverse changes in the environment of the Earth resulting from the introduction of extraterrestrial matter”.
Celestial treaty
It’s okay to send astronauts to the dry, dead dust of the moon, but sending any sort of mission, – rover or human – close to water would contravene that treaty in a big way. And it’s not just water sources – ice caps, volcanoes, even caves, are all out of bounds because they are locations that are more likely to contain substances that could be contaminated.
(This is not mentioned in science-fact movies too often – I'm guessing the new Matt Damon film The Martian doesn't feature any discussion about the red tape they had to wade through to get a manned mission to the Red Planet.)
Of course, there’s nothing to stop any country from simply abrogating the treaty and exploring where they want – it wouldn’t be the first UN treaty to be blithely ignored, after all – but were that to happen, then Bradbury’s fable of the unpredictable, uncontrollable effects of contamination might just play out for real.