While the truth – an ‘alien’ bacterium lurking deep within a Californian lake – is rather closer to home, it markedly raises the odds of ET’s existence.
The excitement lies in the bug’s ability to eat and thrive on arsenic, one of the most toxic chemicals on the planet. It can even incorporate arsenic into its DNA, making it part of its very being.
All 'known' life requires six fundamental elements - carbon, hydrogen, nitrogen, oxygen, phosphorous and sulphur - which provide the building materials for DNA, proteins and fats.
As every other form of known life uses phosphorus rather than arsenic as a key building block of its DNA, the find suggests that a second form of life is with us, right here one Earth.
And if one alien lifeform exists, space enthusiasts argue, it is highly likely there are others out there.
Dr Felisa Wolfe-Simon, from Arizona State University, who led the US researchers, said: ‘Our findings are a reminder that life as we know it could be much more flexible than we generally assume or imagine.
‘If something here on Earth can do something so unexpected, what else can life do that we haven’t seen yet? Now is the time to find out.’
Mono Lake in California is home to one of the oddest lifeforms on the planet, it was revealed
Find: Scientists have discovered bacteria that live on arsenic in Mono lake near Yosemite National Park in California
Astrobiologist Professor Ariel Anbar, also from Arizona State University, who co-authored the study reported today in the journal Science , said: ‘Life as we know it requires particular chemical elements and excludes others. But are those the only options? How different could life be?
'One of the guiding principles in the search for life on other planets, and of our astrobiology programme, is that we should “follow the elements”.
‘Felisa’s study teaches us that we ought to think harder about which elements to follow.’
The bugs, from the GFAJ-1 strain of the Halomonadaceae family were found at the bottom of the salt and arsenic-ridden Mono Lake, near California’s Yosemite National Park.
Experiments showed that they can live like normal life-forms, using phosphorous in their molecules. But when necessary the strain can switch to a ‘weird’ mode of life that relies on arsenic.
The finding bolsters the ‘weird life’ theory coined by
Paul Davies, a British-born professor of cosmology, also at Arizona State University.
He says it is likely that life on Earth has evolved more than once
and the only reason we haven’t found the imposters among us is that we don’t know what we are looking for.
Dr Felisa Wolfe-Simon sampling mud from Mono Lake, California where the strange new form of life was discovered
The professor, who was part of the latest research, cautioned that the discovery that the lake-lurking bacterium can use phosphorus as well as arsenic means it is not a true ‘alien’ with its own tree of life.
But he added: GFAJ-1 may be a pointer to even weirder organisms. The holy grail would be a microbe that contained no phosphorus at all.’
The announcement is the second in as many days that boosts the likelihood of extraterrestrial life. Other US research released yesterday revealed there are three times more stars – and so many more planets - in the universe than previously thought. The research is likely to lift the spirits of the 44 per cent of Britons who believe in little green men.
When more than 2,000 men and women were polled for the Royal Society, just 28 per cent were non-believers, with the remaining 28 per cent saying they simply couldn’t be sure.
In some ways it made sense that an organism should choose arsenic as a substitute for phosphorous, said Prof Anbar.
The element is toxic because its chemical behaviour is so similar to that of phosphorous, allowing it to 'clog up' the works of biochemical machinery.
Is there life out there after all? Speculators will have to wait until Thursday to find out
Is there life out there? Speculators had hoped that a major announcement about alien life would be made
In the last decade, nearly 500 planets have been discovered outside the solar system this way.
In September astronomers announced the discovery of the most Earth-like planet ever found - a rocky world three times the size of our own world, orbiting a star 20 light years away.The planet appears to have an atmosphere, a gravity like our own and could have flowing water on its surface.
The discovery came three years after astronomers found a similar, slightly less habitable planet around the same small red star called Gliese 581 in the constellation of Libra.
The planet, named Gliese g, is 118,000,000,000,000 miles away - so far away that light from its start takes 20 years to reach the Earth.