Erm, just no. I have an old book lying around about Viking, the first mission to the surface of Mars and written before it reached Mars. The book is full of the expectation that they will find life and are rather curious what kind of life. (And the book describes all the instruments and methology)

But no traces of life were found ever.

If there is life on Mars, it is hidden underground in vulcanic active areas and alike and no mission we can do today, could conclude with certainty that there is no life on Mars. But we have been looking real hard.

What's the name of the book?