Mexican crater could give clues to ancient Mars

MERIDA, Mexico, July 31 (Reuters) - A prehistoric crater left by an asteroid collision in Mexico's Yucatan Peninsula could yield clues about what Mars was like billions of years ago, a NASA scientist says.

NASA planetary geologist Adriana Ocampo is digging up rocks buried deep under southeastern Mexico for hints about what impact craters can reveal about planet formation, and says her work could shed light on a giant crater on the surface of Mars.

Astronomers have been puzzled for decades about a huge dent on the surface of Mars -- the largest known crater in the solar system -- and new evidence last month suggests it was caused by the impact of an asteroid the size of the moon.

The Mexican crater, known as Chicxulub, was created when an asteroid that smacked into Earth 65 million years ago in a catastrophe that wiped out around half the planet's species and was maybe responsible for the dinosaurs becoming extinct.

Studying the debris spewed by the collision may answer questions about radical changes in atmosphere that can result from massive asteroid hits, Ocampo, a Colombian based at NASA's Jet Propulsion Laboratory in California, told Reuters. She has been studying the Yucatan crater for a decade.

"It's a natural laboratory because of its similarities to what we can find on other planets like Mars where humans can't go," Ocampo said of Mexico's smaller crater.

The crater on Mars, measuring 5,300 miles (8,530 km) across, is so big that it has left half the planet at a lower elevation.

Mexico's crater is a much smaller 100 miles (160 km) in diameter and is now half a mile underground, where rocks and earth have buried it over millions of years. Space geologists believe the asteroid hit in the Caribbean Sea, probably causing a huge tsunami.

Information from Chicxulub could also give clues about whether or not there was water on the surface of Mars long after the planet was dented by the massive asteroid hit.

Scientists have detected frozen water on the surface of the red planet. Martian seas could have disappeared when the planet was bombarded by smaller meteors that changed its atmosphere and dried it out, Ocampo said

She is looking for similarities between the Yucatan crater -- formed when southern Mexico was under the sea -- and smaller craters on Mars to see if she can detect similar patterns formed by water. (Writing by Mica Rosenberg, editing by Jackie Frank)