Extraterrestrials or simply “aliens” have been able to fascinate many, especially after their grand entrance into our world on their so called “flying saucers” in the last century. In the early stages, the whole concept was considered a complete hoax (perhaps true-reports later indicated that they were U.S.A and soviet aircrafts) but lately many scientists have taken up to task to search for our friends (hopefully!) who share the universe with us.
Astrobiology (as this stream of science is called) aims at studying earth-like planets in other planetary systems and probe for any possibility of life on these. Fifteen years ago the first planet around another sun-like star was discovered by scientists. With the addition of Hubble Space Telescope (HST) and other space telescopes like Kepler, it has been proved that life maybe possible in other planets as well. So far, all known extra-solar planets are gas giants (rather unlikely abodes for life, as we know it). The planets of greater interest are the earth-sized ones, which quite unfortunately are too small for the HST to detect. But then new telescopes are being built which would be able to detect such planets. The dream of searching for signs of life is no longer on the philosopher’s wish list, but on the list of doable and planned human endeavors. Life in other parts of the universe could be in the form of small unicellular organisms or maybe even in the form of our popular green Martians! The possibility that life elsewhere has a biology that is radically different from ours is perhaps the most exciting but equally challenging part of astrobiology (not to mention a ubiquitous theme of science fiction!). Now, we have done very careful reasons about how foreign biology might be different from ours, especially when handling bigger molecules like DNA.
For example, some have speculated that alien life maybe based on silicon (a major component of sand and glass), unlike life on earth, which is based on carbon. The extraterrestrial biology may depend on geothermal energy rather than sunlight. (it was seen that some deep sea creatures here on earth, thrived completely on chemical energy as sunlight wouldn’t reach there). Coming back to the search for “life-bearing” planets such planets maybe many light years away (A light year = 9.5 trillion kilometers). At such distances, earth like worlds will be no more than one pixel of light, even with the most sophisticated telescopes. It simply seems impossible to learn about these planets from these single pixels. Amazingly, the tiny specks of light speak volumes about the planets. From these tiny specks of light, scientists are able to detect chemicals that may have touched it (by splitting the light into component frequencies).
If life is widespread on a planet then its atmosphere will show signs of life. Here on earth all life forms inhale and exhale, consequently the chemistry of our atmosphere has been altered. If life is plentiful on any planet, similar changes in the atmosphere would be substantial enough to notice. But again the uncertainty factor comes in, what would the extra-terrestrial ‘breathe’. Perhaps some day a habitable planet would be found. Although it would be a momentous discovery, would it mean that life is really there? Proof is always a tall order in science, especially while discussing topics like extra-terrestrial life. Proof may be patient. But the answer to a profound question that’s been asked by humanity for decades perhaps would be answered someday, not far off.
Lee Wie Mien Jackson