Long ago, Mars was not so different than the Earth. Vast oceans covered its surface, there was a substantial atmosphere and the environment was much more suitable for life.
We see evidence of this today, in the form of river channels and delta deposits on the surface, relics of Mars's warmer and wetter past. The Mars Reconnaissance Orbiter, circling the red planet since 2006, also detected philo-silicates, a fancy word for clays. Clay forms in the presence of water and their composition could hold the key to discovering whether or not life ever existed on Mars.
If life existed in the ancient oceans of Mars, it would have affected the chemical composition of the clays as they formed. These changes would be detectable by scientific experiments currently in route to Mars.
Hurtling through space at this very moment is the Mars Science Laboratory Curiosity Rover. Scheduled arrive on August 6th, the rover will land in Gale Crater, a mysterious impact crater with a large clay central mound of unknown origin.
Roughly the size of a compact car, Curiosity is the most advanced rover ever to be launched into space. One of its goals is to analyze the composition of these Martian clays in seach of biosignitures (signs of life).
So if you were ever "curious" about whether Martians existed (or exist?!) stay tuned for the landing [[http://www.youtube.com/watch?v=E37Ss9Tm36c]] and keep your eyes on the skies.
Learn more about NASA's mission to Mars here:
Learn more about devastating cuts to NASA's planetary science budget here: