Mars Meteorites Originated from a Cosmic Impact 5 Million Years Ago

A new study shows that the 34-mile-wide Mojave crater on the Red Planet is the source of a major class of Martian meteorites.

An asteroid or a comet hit Mars nearly 5 million years ago. The impact hurled several rocks into space. Few of these rocks travelled millions of miles and landed on Earth.

The ancient rocks called shergottites from Mars have helped several researchers learn about our neighbour. Recently, NASA researchers studied Yamato 000593 (Y000593)- a 30 pound rock from Mars and found tiny tunnels that show that the planet might have supported life in the past.

Mars meteorites found on Earth belong to three categories called shergottites, nakhlites, and chassignites- together known as SNC meteorites. Scientists weren't sure about the origins of shergottites, according to National Geographic.

Now, University of Oslo researchers have used a crater counting technique to show that these meteorites were ejected from the Mojave crater some five million years ago. Crater counting involves counting old and new craters on a terrain to estimate the region's age. More old craters on the surface mean that the terrain is old.

"We tried to find good arguments to convince ourselves that [Mojave Crater] was five million years or younger. You don't expect this size of crater so recently formed, statistically at least," lead author Stephanie Werner, a planetary scientist at the University of Oslo in Norway, told Space.com.

The Mojave crater is 60 kilometers (37 miles) in diameter and located near the equator of Mars. The crater has helped scientists understand Martian surface and early history of the planet.

Researchers also compared mineral composition of Mojave crater with minerals of three shergottites and a non-SNC Maertain meteorite. Their research showed that the wall outcrops of the crater had the same mineral composition as the rocks, National Geographic reported.

"This research is very important for helping us interpret the geochemical data of Mars," Audrey Bouvier, an isotopic geochemist at Western University in Ontario, Canada, told National Gographic. "It has implications for the early evolution of the planet, including its formation, cooling, and the loss of its [global] magnetic field." Bouvier wasn't part of the current research.

The study is published in the journal Science.