Water

Every astronomer is thirsty. Yes! Thirsty of water. It is the most talked about word in the glass cubicles of astronomy theatres and in books written on astronomy. When deep penetrating telescopes, like the Hubble and the Spitzer, return with views from the skies astronomers look for clues relating to the existence of water on those objects. They are happy when they see ice on the moon, Mars, asteroids, comets and elsewhere in the cosmos. The presence of water vapour too increases the possibility of a habitable zone. Why they have affinity for water and vapour is that it raises the possibility of life. Life in any form from microbes to humanity or any other higher forms!
The water molecule has two components - hydrogen and oxygen. Both are very precious. Oxygen you can breathe with and other can be profusely used to create energy. When our Chandrayan confirmed ice on moon all Indian were proud about it. The euphoria generated by patterns of streams on Mars surface lasted a decade until it was confirmed that water did exist on Mars indeed albeit in the form of ice. And now European Space Agency’s Rosetta’s lander Philae has found water on Churyumov Gerasimenko the comet.
Besides Hydrogen and Oxygen, Carbon for the formation of fuel and Nitrogen are important. This will entail the formation of amino acids.
What is common to the solar system could be possible anywhere in the light years of the cosmos. However it is to be seen if life can exist without these basic elements. There is a possibility that what we consider as building blocks of life may then have more hues of combinations. May be some other life exists around us which our senses may not have the receptors to feel them!!