I'll give you an interesting idea: technical problems or other happenstance mean the probe sends back information that is misinterpreted. A smudge, an odd weather pattern that turns out to be just that, or whatever it may be. And as a result, that fuels speculation on life (bacterial or otherwise), simple plant life (which was considered a real possibility), etc, spurring more space interest.
Hard to say, when we haven't find signs about life. And even if there was life, it was probably something bacteria level life. Only way that it could get such photos from space is that there would has been so advanced civilisation that there is still large buildings left.
I think this should go to Alien Space Bats, as that's the only way I can see something interesting about Mars being picked up from space.