In the last little while NASA has really been ramping up its search for habitable planets outside of our solar system and, by extension, for extraterrestrial life. Today NASA held a panel which has had some serious buzz around it. Lets be honest here; you bring together some astrobiologist, an organic chemist and to talk about a major discovery that will impact the search for evidence of extraterrestrial life and people are going to get really excited. So what was it all the buzz about? A new way to view life.
Or rather, an exception to our rules regarding what makes up life. What they have discovered is a microbe which can substitute arsenic for phosphorus in its basic, molecular make-up. That may not sound like such a big deal, but when you consider that all life we know of so far uses carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur as its basic building blocks, and that phosphorus is essential in forming DNA and RNA, you can see the kind of paradigm shift which biologists are facing and the potential opportunities for the discovery of life on planets and moons which we may not have considered before.
It is still the very early days for this kind of study and there are a lot of questions which still need to be asked, but the implications of this discovery are huge.
Also, io9 has a really nice summary of the findings and the whole event today