[seanflyon]

> Why not send bacteria which may evolve or may create environment for other form of life?

We should, but there are 2 reasons we are not doings so right now.

1) We don't want to destroy our ability to determine if there was life on Mars in the past, which would be much harder to recognize as martian life if earth life was all around.

2) It is quite difficult to come up with something that could survive and reproduce on Mars.

I don't think (1) is a compelling enough reason and (2) is just another way of saying that it's hard, so I completely agree, we should do it.