Click the "Next" button for our list of the most audacious attempts to explore Mars.
FIRST STOP: Mars 2
NEXT: Mariner 9 in Mars Orbit
NEXT: Viking Landers' Mars Success
NEXT: Tiny Mars Rover Sojourner
NEXT: Japan's Mars Emissary
NEXT: Mars Odyssey Lives On
Opportunity, however, is still alive and continues to explore the Martian surface. It has traveled 22.11 miles (35.58 kilometers) as of February 2013. [Latest Mars Pictures by Opportunity]
NEXT: Europe's Mars Orbiter and Lander
NEXT: A Phoenix on Mars
NEXT: Eyes of Mars Reconnaissance Orbiter
NEXT: Russia and China Aim for Mars
NEXT: Mars Rover Curiosity - a Martian Car.