Whenever humans arrive on Mars, they're going to find it a difficult place to exist. Mars is cold, with an average surface ...

One of the great unsolved problems in modern planetary science is written on the surface of Mars. Mars has canyons that were carved by rivers, so it was once warm enough for liquid water. How—and ...

An accounting of all the water that should have been and gone on Mars’s surface has come up with a discrepancy that shows ...

Liquid water once shaped the Martian landscape dramatically, carving valleys, filling lakes, and forming vast oceans. Billions of years ago, during Mars' early days known as the Noachian and Hesperian ...

NASA finds evidence on Mars of water that flowed billions of years ago, broadening the possibilities for life on the Red ...

For years, scientists have been intrigued by mysterious dark streaks running down the slopes of Martian cliffs and craters. These marks, called slope streaks and recurring slope lineae (RSLs), have ...

Mars is the fourth planet from the sun and has a distinct rusty red appearance and two unusual moons. The Red Planet is a cold, desert world within our solar system. It has a very thin atmosphere, but ...