Mars. This mysterious planet has been inspiration for Sci-Fi movies for many decades. It is thought to have once supported life, especially after radar data from Mars Express and the Mars Reconnaissance Orbiter have revealed the presence of large quantities of ice at different locations on the planet. The largest volcano in our Solar System, Olympus Mons, is located on Mars, as well as the largest canyon, Valles Marineris, which is 2,500 miles long. Another interesting fact about the planet is that one of its two moons, Phobos, may crash into Mars in several decades because of gravitation forces.