Looking for Water & Life in Our Universe

Life on planets is probably an interesting question all beings wonder about all the time.  But really, are we all alone and how do we find out if life really exists elsewhere in the Universe?
 
One way is to travel to the planets, either with  probes or with human operated spacecrafts.

Mars is at present the only planet in our Solar System where there is a strong possibility of finding life, either in past or present.  But how do we find life on planets outside of our Solar System?

First you have to find the stars that have planets. There are too many stars to analyze them all, so you have to choose a small part of the sky as your starting point. Next you have to decide what kind of planets you are looking for.

With Earth-based telescopes, the only planets we have detected around other stars have been giant gaseous worlds, like Jupiter, over 10 times the diameter of the Earth. Scientists believe we should be looking for rocky, Earth-like planets, because a solid surface is needed on which organic molecules can form and develop into life.

The basic requirements for survival today are liquid water, natural compounds and an energy source, such as the Sun or volcanoes.  Although it may seem unlikely that life existed on Mars' intimidating surface, scientists are fascinated by the possibility that compound organisms, maybe microbes, may have gained a grip in olden times when Mars may have been warmer and wetter.  Maybe organisms migrated below ground, where conditions were gentler.

In the 1980s and 1990s, biologists discovered that microbial life has an amazing flexibility for surviving in extreme environments -- whether amazingly hot, or cold, or dry, or under huge pressures -- that would be completely unwelcoming to humans or complex animals.  These discoveries affected how scientists view life on Mars.  Perhaps life thrived billions of years ago in an active volcanic spring. Perhaps life in some form could persist today in underground springs warmed by heat vents around blazing volcanoes, or even trapped under thick ice caps.

The debate rages on.  How wet was the planet, and for how long, and when? What happened to all the liquid water?  To answer these questions, agencies like NASA look at the miscellaneous displays of clues that water might have left on Mars, for instance, as the rocks littering the surface.   As you know rocks are made of minerals. On Earth, some minerals form only in connection with liquid water.  Other minerals are deeply changed when hot water runs through them.  The mineral make-up of Martian rocks will give scientists a better understanding of the liquid water on the planet, which is one of the important parts to understanding whether Mars was ever home to living creatures.

Missions to Mars

Mars Probes and Rovers Quiz

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