When NASA sent two rovers to Mars they were not quite sure what all they would find. What they ended up finding far exceeded expectations and has proven that the possible foundations for life do exist on other planets.
The scientists were eventually able to conclude that cloud formations do form on the planet and they can, in fact, make it snow on Mars. Scientists were able to observe this phenomenon using the LIDAR instrument (Light Detection and Ranging).
"But the really amazing data came from the LIDAR instrument, which was able to track the formation of the clouds at the atmosphere's boundary layer. Cloud formation became more pronounced as the summer gradually faded and the atmosphere cooled at night, and the scientists were eventually able to detect cirrus-like clouds as they dropped 'tilted vertical sheets' of ice particles back to the surface of the planet. In short, they watched it snow."
Scientists have been able to conclude that Mars does have an active water cycle on the planet but it is presumed that the cycle is dying as the planet appears to have had, at one point, flowing rivers.
What this all means to us is that the possibility for life outside of our planet, while remote, is completely possible. At some point, man may have to leave this planet, and this new discovery of liquid water greatly increases the odds of longer-term human survival.