New discoveries raise chances of finding alien life:

Is there life out there?

By Pramod De Silva

Could life be unique to our Planet Earth? In other words, are we alone in the universe? Let alone intelligent life, could at least microbial life forms exist in other worlds far beyond the solar system?

These questions have still not been answered, but scientists are increasingly confident that we would get an answer in the next 20 years.

“The evidence is just getting stronger and stronger,” says Carl Pilcher, Director of NASA’s Astrobiology Institute, which studies the origins, evolution and possibilities of life in the universe. “I think anybody looking at this evidence is going to say, ‘There’s got to be life out there’.”

Seth Shostak, senior astronomer at the SETI (Search for Extra Terrestrial Intelligence) Institute in California, is another believer. He said that given the mounting evidence, to believe now that Earth is the only place harbouring life is essentially like believing in miracles.

One of the first pointers in this direction is the discovery of a large number of ‘exoplanets’ - planets outside our solar system - by space telescopes. At least some of these planets, a number of which are earth-sized, could harbour life even in a primordial form. There could be billions of such planets in all the galaxies, so there is a chance that life is present in some of them. Who knows, some planets could be home to civilisations far more advanced than ours.

Our conventional wisdom is that life needs ingredients such as carbon and oxygen to thrive. But what if they do not? What if life can thrive on other, more exotic ingredients, like Arsenic? This is exactly what NASA claimed in a recent news conference.

It said that an organism found in the mud of California’s Mono Lake can live and grow entirely off this deadly chemical - raising hopes that similar creatures could exist in even more hostile environments.

The arsenic-loving bacteria

The new finding describes how a bacterium takes a detour from normal metabolism, swapping the common element phosphorus for toxic arsenic, and flourishes. Six major elements have long been considered essential for life - carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur. The new discovery has changed that definition of life.

“This is a microbe that has solved the problem of how to live in a different way,” said Felisa Wolfe-Simon of Palo Alto, the young NASA astrobiology fellow who led the effort, during a Washington news conference.

Building blocks

They found that a bacterium, a member of the common Halomonadaceae family, not only lives phosphate-free, but can even successfully incorporate arsenic into its DNA, RNA and other biological building blocks.

The discovery of such life forms in our own backyard is a big boost for those searching the skies for extra terrestrials. Of course, NASA’s findings are being challenged by some sections of the scientific community, saying the research was flawed. Nevertheless, the research is an indication that life may exist, but not as we know it.

Another recent discovery has boosted the hopes of those searching for Extra Terrestrials. Last week, a Yale University astronomer said he estimates there are 300 sextillion stars - triple the previous number. Moreover, Lisa Kaltenegger of Harvard University says scientists now believe that as many as half the stars in our galaxy have planets that are two to 10 times the size of Earth - “super Earths” which might sustain life.

The potential for life is likely to be high in planets orbiting stars like our sun, and surprisingly, red dwarfs. Up to 90 percent of the stars in the universe are red dwarf stars. Scientists say conditions near these small stars wouldn’t be similar to Earth, but would still be acceptable for life. These findings have increased the number of potential homes for life and broadened the definition of what life is. The probability for finding alien life is now higher than ever before.

There’s also a chance that a telescope could spot a planet with an atmosphere that suggests photosynthesis is occurring. There is also the possibility of finding alien life on Earth itself, perhaps in a meteorite, or something with an entirely different set of DNA, as suggested by the Mono Lake bacteria.

Restricted scope

Intelligent life may exist elsewhere in the universe, but our first encounter could well be with a microbe, which would not, of course, say “take me to your leader”. A robotic space mission that hunts for life in other planets will not be able to travel to the stars and planets millions of light years away, but 20-25 light years could well be a possibility. This will, of course, restrict our scope for finding intelligent life.

We might not even have to look that far. If life is going to be found, Mars is the most likely candidate. Any life is probably underground where there is water, astronomers say. Other possibilities include Jupiter’s moon Europa and Saturn’s moons Enceladus and Titan. These are well within the range of robotic and someday, manned space missions.

We have been sending radio signals out to space for nearly 100 years. Aliens could intercept them and reply or we might intercept an alien transmission. This is what the SETI Institute does.

The only problem here is the time lag - if we intercept an intelligent signal coming from 300 light years away, our reply will take 300 years to reach them. (A light year is the distance light travels in a year). Their reply, in turn, will take another 300 years to reach Earth. Nevertheless, getting such a signal will be an earth-shattering breakthrough.

With all these developments, including ever more powerful telescopes and space probes, there is a greater chance of life being found elsewhere in the solar system and the universe within the next two decades.

Life finds a way even in the harshest environments and the worlds out there in space may be teaming with forms of life that we cannot even imagine. If we are not alone in the universe, that is incredible. On the other hand if we are, that is even more incredible.