Mars has had its share of mechanical visitors from Earth. But as of today, NASA's Mars Odyssey orbiter has officially been the red planet's longest-staying guest.Full story
A six-year study of methane in Mars' atmosphere shows the planet is far from dead, though whether it is merely geologically active or host to microbial life is unknown. Full story
Some of the gullies that cut the sides of Martian craters were likely formed by meltwater from glaciers that existed a few million years ago, when Mars was wetter than it is now, a new study suggests. Full story
Data NASA's Mars Global Surveyor was combined to reveal this orbital view of the north polar region of Mars, including its ice-rich polar cap, which is is approximately 621 miles across.