To date there have been 42 missions to Mars, with half of them being complete failures. Other than the Earth it is the most studied planet in the Solar System, and for centuries it has been at the heart of wild speculation and groundbreaking scientific discoveries. Observations of Mars have not only revealed otherwise unknown secrets but also posed new and exciting questions, and it is for these reasons that it has become the most intriguing planetary body of our time. In fact, the structure of Mars suggests that it was once much more geologically active than it is now, and the presence of huge craters also points to large-scale impacts in its early formation.
Image source: NASA