A Nasa rocket carrying the Kepler space telescope was due to take off from Florida early this morning in the hope of finally answering the question that has been tantalising the world for as long as any scientifically curious human being can remember: has Barack Obama's hair gone grey after only six stressful weeks in the White House?

That's certainly the question that has been transfixing Americans, to judge by the coverage devoted to this story by The New York Times, a newspaper whose masthead bears its legendary motto, “Yes, we employed Jayson Blair, but that doesn't mean that everything we print is made up”.

Actually, the motto of The New York Times is, “All the news that's fit to print”. This means that on a day when this journal could have been serving its readers details of Gordon Brown's visit to Washington to meet Barack Obama, along with a taste of Gordon Brown's delivery to Congress of an historic speech crammed full of such memorable phrases as [subs: please check through GB's speech for a memorable phrase to insert here. My mind's a complete blank on this one], the editors of The New York Times reckoned instead that they had something far more fit to print.

They calculated that a story that more closely addressed the concerns of a world struggling through its most brutal recession in decades was whether, (a) the President of the United States was turning rapidly grey with the burdens of office; (b) whether the President had turned grey a while back, but the flecks had only now begun to show because - given that he no longer has to go to the supermarket in person on account of his having 397 aides to do his family's weekly grocery shop for him - he's too embarrassed to scribble “bottle of Grecian 2000” at the bottom of his aide's shopping list; (c) he might be deliberately dyeing it grey to lend himself gravitas; or (d) his hair changed colour during that Oval Office news conference with Brown - the same way many people, when assaulted by a trauma, turn grey overnight.

No, wait a second! Now that I read the Nasa announcement a little more closely it turns out that the mystery the Kepler mission is hoping to solve has nothing to do with Obama's hair. Apparently it is going to spend the next few years scouring space in search of planets that might harbour life; even if it is only very simple life forms, like Sarah Palin.

This is the issue, it seems, that has been making scientists so restless for years: the search for life beyond the solar system. You might consider this goal needlessly ambitious, given how many tasks it might be more useful to carry out first; such as making London Underground's Circle Line function in a way that didn't make its users wonder if the timetable was compiled from numbers yelled out at random by a bingo-caller.

But, frankly, that would be small-minded of us. Yes, certainly there are banks to be bailed out, and whole industries to be rescued from oblivion, and many jobs to be saved, and the day will come soon enough when Gordon Brown will no longer be able to do all of this on his own.

However, scientists must be liberated to focus their gaze on a more distant horizon than the rest of us. They have been put on this earth to dream; to provide answers to questions we didn't even know were questions; to hypothesise audaciously about mankind's future. Their duty is to fill a Petri dish with microbes and to be paid a large grant to supervise these germs in case, by 2017, they turn into something that might make a big enough footnote in Scientific American to command a fresh grant.

Scientists have to operate on a long time-scale partly because grasping how things work in Nature seems to dawn on them quite slowly. For example, not a single scientist seemed to notice that it was a force called “gravity” that prevented apples flying upwards into the sky - until Sir Isaac Newton happened to be sitting beneath an apple tree one day when a Cox's Orange Pippin fell forcefully on to his head, provoking him to shriek out in pain and, as a consequence, establish his now famous place in history as the man who invented the first swear word.

To a scientist, spending the next 30 years monitoring whether the Kepler telescope has spotted an alien amoeba on a planet to which it would take you six million light years to travel in person (742 million if you were travelling by Circle Line), would seem to them to pass as briskly as the blink of an eye.

Look at the American astronomer Frank Drake. He began looking for extraterrestrial life at the Green Bank telescope in West Virginia in 1960, and it doesn't seem to have bothered anyone involved that, after 50 years, not a sausage has yet been sighted or heard. That Drake carefully crafted an equation by which he narrowed the potential number of intelligent civilisations in our galaxy down to a figure ranging from one to 50 million prompts you to wonder if astronomers have really nailed this one down. But we can still admire the purity of their ambition, which they fan and stoke on all our grateful behalfs.

Of course, there is a small chance - what with Florida (“The hanging chad state”) being the sort of place where life can take unpredictable turns - that the Nasa spacecraft never even made it off the launch pad at Cape Canaveral this morning.

But if it didn't, then it will any day now - sending Kepler zooming off to the darkest crevices of our galaxy. So, one way or another, we will soon know once and for all whether there are little green men out there. And if their hair is turning grey.

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