Almost everywhere you go on Earth, you encounter alien species that were introduced – often inadvertently – by humans. Now it seems possible that we have done the same to Mars. Despite stringent rules designed to prevent contamination, Earth microbes may have reached the Red Planet.
That might look like a blow for efforts to detect Martian life. But, ironically, it may end up being the opposite. Some planetary scientists argue that if contamination is already likely, we should now throw caution to the wind (see "Overprotection may be hampering hunt for Mars life"). The strict rules actually hamper the search for life by adding unnecessary costs to missions, they say.
Is there a case for relaxing the rules? Perhaps. If Mars has its own life, it should be different enough from Earth life for us to recognise it. If it doesn't, any bugs we find will be recognisably terrestrial. In either case, Earth life will struggle to colonise Mars. Recent arrivals are unlikely to thrive in the harsh conditions, and the possibility of them outcompeting any natives is about as likely as parrots colonising Antarctica and ousting the penguins.
Let the terraforming begin. To read more, click here.