(CNN) — Here’s a look at the exploration of Mars. The United States, Soviet Union and China are the only three countries to land a spacecraft on Mars. There have been nine successful US Mars landings: Viking 1 and Viking 2 (both 1976), Pathfinder (1997 ...

Uncover the 25 Things NASA Doesn't Want You to Know About Mars. From volcanic activity to mysterious anomalies, explore the Red Planet's hidden truths and

Skylights, openings in the surface of Mars that descend down into caves, have been found on Mars, along with signatures for the presence of water ice. New images from the Mars Express orbiter reveal evidence of a past ice age at Mars's mid-latitudes and ...

Image – resolution is 25 centimeters (10 inches) per pixel. During its first week of observations from low orbit, NASA’s newest Mars spacecraft is already revealing new clues about both recent and ancient environments on the red planet. Scientists hope ...