Are there other earths in the universe?

The discovery of planets with shape and size akin to earth generates immense interest.

Last Updated: May 03, 2010, 11:51 AM IST

Smita Mishra

If our preceding generation was obsessed with world war woes, agrarian crisis, epidemics and surging nationalist sentiments, we are gripped with the looming concern over global warming, economic crisis, fanciful inventions and hunt for life beyond our planet.

A civilization like ours which is no longer troubled with the basic needs of survival, which has time and opulence to think beyond the necessities of life, invests in inventions and explorations to find both the tools of destruction as well as the elixir of life.

No wonder our scientists are preoccupied at this hour with finding two things - the gene that can create life in a lab and the possibility of life on other planets. We might be on the threshold of building the invisibility cloak, mind reading machines, humanized robots and natural body parts but the origin of life is still a mystery.

Almost three decades ago, there was a general feeling among scientists that life resulted on earth by co-incidental chemical reactions. But now it has changed to a firmer belief that life can be re-created and there are possible traces of it beyond our planet.

Alien microbes are the new objects of interest for our researchers as is intelligent extra terrestrial life.

Are we alone?

Considering the vastness of the universe and the number of galaxies, stars and the planets encircling them, it is not just a fanciful thought to hope for the possibility of life in some remote corner of the universe. The Drake equation (is an equation to organize our guesses about the potential number of alien civilizations in the Milky Way) is based on this very principle.

Besides, the chemistry needed to build life is abundant throughout the universe -- in comets, in the interstellar medium, in the planetary atmospheres, in the outer solar system bodies and in living organisms, the researchers with NASA and SETI institutes believe. So the probability that the chemicals needed to create life must have conspired together to form breathing, living beings in some distant planet under favourable winds, cannot be treated as absolutely unfeasible.

Why search for Earth like planets?

Our scientists have been able to discover more than 100 planets in the last ten years but most of them are gigantic monsters, ridiculously close to their suns, with hardly ideal conditions for life. So the discovery of planets with shape and size akin to earth generates immense interest because this shape is suitable for harboring oceans and huge water bodies.

But can we really be sure if an unknown form of life really needs water or earth like conditions to survive?

What, if the carbon monoxide, or sulphor dioxide, treated as poison by us, are necessary ingredients for their survival? What if they drink ammonia instead of water and live on arsenic and radioactive elements?

Did Mars support life?

For years we have looked at our red neighbour, Mars with a lot of hope and optimism. Polar ice caps, similar axial tilt as Earth, island like structures suggesting massive floods in the past and the composition of its atmosphere are evidences which make our researches hopeful that life once thrived on the red planet.

But if water did once flow on Mars, where did it go? Did life evolve there? Is it still lurking somewhere deep inside the surface of the planet? The questions are yet to be answered.

Even the existence of micro-organisms such as `methanogens`, producing huge amounts of gas in the red planet is not considered scientifically viable as of now. But one group of scientists believes that they lurk below the hard rocky surface of Mars and are a key to further possibilities.

Why aliens have not come searching for us?

For centuries, incidents of UFOs being spotted have been reported world wide. Shining silvery discs, speeding fireballs, strangely shaped crafts, gigantic discs, curiously shaped objects in sky and bright travelling lights have been seen since ages by people across the world.

Be it the crop circles of the 1970s, the appearance of which in innumerable farms had been associated with ufological activities or the ‘Wow Signal’ caught by SETI which is still regarded as the voice or signal sent by some alien species and remains unexplained till date, the concrete evidence of intelligent life beyond Earth still eludes us.

But why have we not yet been discovered by such species, if they exist? The way we are trying hard from ages to establish contact with aliens, why have they not attempted anything like that? Or have they? If so many alien species are paying us a visit, why is the entire affair so quiet? If the UFOs are spotted by people, why are they not spotted by the powerful surveillance radars of various countries?

Or may be they are spotted and it is all kept a secret a la Independence Day.

Our conjecture about the possibility of extraterrestrial life is mainly based on probability.

When India`s Chandrayaan-I mission identified tunnels below the surface of the moon, a top space scientist commented that human habitation could be possible in those "tubes" in the future. This is again highly speculative.

Traces of microbes have been reported by the Viking probe on Mars, structures of nano bacteria were found on meteorite ALH84001 in 1996a and they are believed to be existing even on Titan. But then we cannot ignore the fact that these bacteria, capable of surviving under harsh conditions, might have left the surface of earth millions of years ago!

SETI failed in its mission of searching for aliens, after investing millions in tracking extraterrestrial radio signals. But can we rule out the fact that if intelligent aliens existed, they may not be transmitting any signals; and their brains and senses might be on a level, much different from ours?

Ruling out the possibility of life, without searching every nook and corner of the zillions of planets in the universe would be pessimism at its worst. In our search for life beyond earth, we cannot take absence of evidence as evidence of absence.

But there is an inherent flaw in our search system. We are hoping to find beings like us - with heart, circulatory system, lungs and cellular body. But we need to retune our frequencies to a level beyond this. Our researchers need to do more and keep their minds open. Lord Martin Rees, the Astronomer Royal of UK, has said aliens could be amongst us and we may not be able to recognise them.

Who knows we have aliens floating invisibly in our living rooms and we are searching for them in distant planets!