I was just thinking about this having done a post on Silicon based lifeforms.
Everything in the Universe appears to be alive, everything goes through life cycles from stars to cellular structures. Think about it...all stars are
born, live for awhile, and then die...same as every other living thing. Planets go through cycles and weather changes. Organic life does as well.
Maybe we have not been able to locate exact proof of life beyond Earth because our definition of "life" is to narrow. Maybe all life does not
follow the basic rules that we think it does...ie must be carbon based, etc. to be counted as life.
Maybe our science is not yet fully developed enough to understand that everything in the universe is living and interconnected. Afterall, who is to
say that Black Holes, the bending of space-time, and the very fabric of the universe (Superstrings, etc.) is not "living".
There are obvious structures on the surface of Mars, but even that aside maybe the very rocks that make up Mars are in effect living. It seems to me
that if we do not expand our way of thinking while exploring the universe we are going to miss out on clear opportunities. Maybe life does not stop
with carbon based life forms...
...I could go on, but I think you all get the point!