By Grace Kim

More than 635,000 meteorites collided into the surface of Mars, creating impact craters at least 1 kilometer wide, reported a science journal Sunday.

A research team from the University of Colorado Boulder published a new Martian atlas, the largest database ever compiled of impacts on a planet or moon in our solar system. The researchers counted, outlined and catalogued 635,000 craters over four years.

"This database is a giant tool that will be helpful in scores of future Mars studies ranging from age-dating and erosion to planetary habitability, and to other applications we have not even thought of yet," said Stuart Robins, the study leader.

The atlas can trace the changes of the planet’s surface since the crater database differentiates between craters that have been filled versus those that have eroded by different processes over time.

"Many of the large impact craters generated hydrothermal systems that could have created unique, locally habitable environments that lasted for thousands or millions of years, assuming there was water in the planet’s crust at the time,” said Brian Hynek, co-author with Robins.

He added, however, that large impact craters can wipe out life forms, as evident from the Chicxulub impact that is thought to have killed off Earth’s dinosaurs 65 million years ago.

So far, scientists have catalogued about 200 impact craters on Earth. They are more difficult to see than those on Mars because of Earth’s atmosphere, lifeforms and tectonic activity.

The new atlas combined with the data from Mercury and the moon is expected to provide an understanding of Earth’s past.