A depiction of the rover Curiosity, of NASA's Mars Science Laboratory mission, as it uses its Chemistry and Camera (ChemCam) instrument to investigate the composition of a rock surface. Photo: NASA/JPL-Caltech

Mars may be more like Earth than people think. It turns out there is water on Mars.

The new information was discovered by a robot. The car-sized robot runs on wheels. Its name is Curiosity. In 2011, the United States sent Curiosity to Mars to see if life there is possible.

Curiosity traveled through space in a rocket. The trip took seven months. It landed on Mars last year. Its mission is to learn about what it is like on Mars. Scientists want to know if life ever existed there. Scientists also are curious if people could explore Mars safely.

Curiosity has sent back important information about Mars. The fact that scientists are most excited about? Curiosity has spotted water. The water was found in Mars' red dust. Scientists found something else. This dust seems to cover the whole planet. Strong storms probably spread the dust.

Robot Has Special Tools

Curiosity has special cameras, measuring tools and computers. All that equipment is for gathering information. Curiosity used a special tool to cook up a tiny bit of dirt. It found that water makes up a tiny part of the dirt. Scientists think this water came from Mars' very thin air.

This discovery may make travel to Mars possible. Explorers could get the water they need from its dirt.

"It's actually kind of exciting," said John Grotzinger. He is a geologist. His job is to study rocks.

Maybe Mars was once more like Earth than scientists believed.