The Drake Equation - Is Methane a Sign of Life?

There's something called the Drake equation if you take the number of stars and you multiply it by the probability that star has a planet which we used to think was quite small. As long as that number is not absolutely mathematically zero the Drake equation tells you that there are other things alive out there in our universe. If we find evidence for life on Mars i personally will be relieved because the notion that we are the only living things in this universe is terribly frightening to me. One of his missions is looking for methane traces on Mars and methane possibly is a sign of life.