NASA has announced that it has discovered a completely alien life form, and it didn't have to leave earth to find it:
At its conference today, NASA scientist Felisa Wolfe-Simon will announce that NASA has found a bacteria whose DNA is completely alien to what we know today. Instead of using phosphorus, the bacteria uses arsenic.
All life on Earth is made of six components: carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur. Every being, from the smallest amoeba to the largest whale, shares the same life stream. Our DNA blocks are all the same.
But not this one. This one is completely different. Discovered in poisonous Mono Lake, California, this bacteria is made of arsenic, something that was thought to be completely impossible. While Wolfe-Simon and other scientists theorized that this could be possible, this is the first discovery. The implications of this discovery are enormous to our understanding of life itself and the possibility of finding beings in other planets that don’t have to be like planet Earth.Read more at Wired.
One way to think of this as a game changer in the search for life beyond earth, says Carl Zimmer, is that it broadens the scope we'd using to look for life. Zimmer addresses those who are skeptical that NASA has found a form of life Zimmer addresses these as well.
Update: Commenting at our Facebook page Tom Faber says "the wired/gizmodo article is really inaccurate, I'm shocked they haven't posted a correction already. More detailed report at http://www.nytimes.com/2010/12/03/science/03arsenic.html?hp."