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It is a story of science fiction turned reality show - a story befitting its namesake Kepler, the early 17th-century German mathematician and astronomer who discovered the three laws of planetary motion that are one of the most important theoretical constructs that provide the basis of astronomy. The US$571 million (Bt 20.6 billion)Nasa project is a one-tonne spacecraft that carries a 55 inch-diameter telescope - a 95-million-pixel digital camera. Kepler will remain in orbit for three and a half years, even though its camera is designed to last six.

The mission of Kepler is to discover earth-like planets of other stars in the Milky Way. It is to find these earth-like bodies in an earth-like place - the so-called "Goldilocks or Habitable Zone" - a zone not too hot, not too cold, that supports water in liquid form, and hence life.

Basically, Kepler will perform a "planetary census" - to find how many rare planets like earth there are in the cosmos. But because the process of detecting and measuring the "blips" or eclipses made by these planets while orbiting their stars - which will tell us facts about their size and environment - is time consuming, it will take at least three years before any findings can be put forward to the public.

Kepler will skip the oddball gigantic planets and focus on the modest-size ones, like earth, that the late American astronomer Carl Sagan described as the "pale blue dots".

Goldilocks (and the Three Bears) is an old English fairy tale originally written by Robert Southey about an impudent, foul-mouthed, ugly, dirty old woman - a vagrant - who goes into the home of three very good-natured, trusting, harmless, tidy and hospitable bears, and makes a mess of their place and leaves without a trace. In later adaptations the old woman was changed into a pretty little girl and the term "Goldilocks" evolved, eventually coming to connote the notion of "just right" that was taken proudly by some to be a description of the British Isles.

In astrobiology, a Goldilocks zone denotes a place where conditions are just right for a disc of dust and gas to coalesce into a neatly ordered planetary system. It is an area of space in which a planet is just the right distance from its star so that its surface is not too hot or too cold. In other words, just like ours.

By the end of 2007, about 250 exoplanets - planets orbiting stars (their suns) besides our sun - had been found, but among them only a few have been found in the Goldilocks zone. To date, the most earth-like planet known in this "just-right" zone is Gilese 581c, which orbits a massive red star called Gilese 581 in the Libra constellation. Gilese 581c, about 20.5 light years away, is the closest such body to earth, with its size not much larger than earth's own (19,000 kilometres in diameter as opposed to earth's 12,700).

Gilese 581c orbits its "sun" very closely, completing it in just 13 earth days, which should make the planet's surface too hot for life, but it does not, because Gilese 581's surface temperature is only about 1/50th that of our sun. As it turns out, Gilese 581c's surface temperature is estimated to range between 32 and 102 degrees Fahrenheit. Despite these similarities, Gilese 581c's gravity is twice as strong as earth's and it receives a high level of radiation from its star, two conditions that normally prohibit life from developing.

But scientific discoveries in the past 30 years have revealed that there are more forms of life than we previously knew. Scientists have found microbes in nuclear reactors, microbes that love acid, microbes that swim in boiling-hot water, and microbes that die in the presence of oxygen. These are lives that exist in extreme environments and hence, the Goldilocks zone may be much bigger than we thought.

But regardless of whether the zone is small or large, there is no denying that earth indeed has hit a cosmic jackpot that gives the term "just-right" its profound and ethereal meaning. Our planet sits between two worlds - Venus and Mars - that have been devastated by climate catastrophes. Earth's climate and eco-system is so complex, where everything seems to be miraculously in perfect balance. It has been so until the havoc induced by man-made global warming, which has started to take the lustre out of nature's wonders.

Today the odds on proving the existence of extraterrestrial intelligence have been shortened from 1,000-1 to 100-1. Discovering whether or not there are alien lives on Gilese 581c or any other earth-like planet - and if there are, will we even recognise them - will remain a major quest for scientific discovery. After all, if we don't even understand how life and consciousness began in our world, imagine how difficult it will be to find out how life could arise, and in what shape and form, anywhere else. Indeed, there are also theories that life and consciousness are not just incidental by-products of nature, but are central factors in the formation of the universe.

Southey's "Goldilocks" is sometimes viewed as a cautionary tale that imparts a lesson about the hazards of wandering off and exploring unknown territory. It is a tale about an intruder who could not control herself with the possessions of others. Man possesses two character traits that have helped build and destroy our own earth. They are the love of learning - the unfathomable curiosity that kills herds of cats - and the limitless ability to destroy.

One gives us a fuller and richer life and a better world, the other takes it away. Someday soon we may find life on other planets, even intelligent life, but what we do then with those planets and lives, or, what they do to us, is a 64,000-dollar question. Carl Sagan, who was the pioneer of exobiology and who dedicated his life to promoting the search for extraterrestrial intelligence, warned against human beings' tendency to anthropocentrism.

"If there is life on Mars, then I believe we should do nothing to disturb that life. Mars, then belongs to the Martians, even if they are microbes."

Beam me up, Scotty.