Oldest Martian Meteorite on Earth Traced to Its Origin on the Red Planet

To date, researchers have collected 175 samples of Mars rocks on Earth. One of those Martian meteorites that barreled across space, named NWA 7034 or Black Beauty, was vastly different than the rest, in that it contained sharp fragments of different types of rock clumped together. Called breccia, this type of rock is the only one of its kind ever found from Mars, reports Kiona Smith for Inverse.

Now, researchers have pinpointed the crater on Mars where NWA 7034 came from, adding to suspicions that the Red Planet was once habitable. The study was published this week in Nature Communications.

The space rock, recovered from the Western Sahara of Africa in 2011, formed 4.5 billion years ago and slammed into Earth after an asteroid impact sent it flying across space five to ten million years ago. Using a supercomputer and a machine learning algorithm, researchers have pinpointed the meteorite's origin to the Terra Cimmeria-Sirenum area on the Red Planet's southern hemisphere. When the rock formed, this area on Mars may have been comparable to Iceland today, a statement explains. Chemical signatures on the meteorite indicate that Mars also had volcanic activity similar to that on Earth, and may help researchers compare the formation history of Earth and Mars.  

"This meteorite recorded the first stage of the evolution of Mars and, by extension, of all terrestrial planets, including the Earth," says Valerie Payré, a planetary scientist and study author from Northern Arizona University, in a statement. "As the Earth lost its old surface mainly due to plate tectonics, observing such settings in extremely ancient terrains on Mars is a rare window into the ancient Earth surface that we lost a long time ago."

The team named the crater on Mars Karratha, after a city in western Australia known for its preserved rock formations and where some of Earth's oldest rocks are found, reports Michelle Starr for Science Alert. To see which crater the meteorite belonged to, researchers analyzed 90 million craters with the algorithm in 24 hours and found that several individual impact events contributed to the formation of Black Beauty.

First, the oldest fragments in the meteor were lifted 1.5 billion years ago from the Khujirt crater on Mars. After the material fell back to the planet, it sat there until five to ten million years ago, when the impact that created the Karratha crater sent Black Beauty on its journey to Earth, Science Alert reports. Other previous research found shocks to the meteorite's zircon crystals suggesting that another impact helped form Black Beauty, but the location of this event remains unknown.

Overall, the findings show that the area where NWA 7034 was first ejected from is a relic of primordial Martian crust. Researchers are now hoping their method of using the algorithm to identify craters can help scientists find the origin of other Martian meteorites on Earth, per Inverse.

"This work paves the road to locate the ejection site of other Martian meteorites that will provide the most exhaustive view of the geological history of Mars and will answer one of the most intriguing questions: why Mars, now dry and cold, evolved so differently from Earth, a flourishing planet for life?" Payré says in a statement.

Elizabeth Gamillo | | READ MORE

Elizabeth Gamillo is a correspondent for Smithsonian and a science journalist based in Milwaukee, Wisconsin. She has written for Science magazine as their 2018 AAAS Diverse Voices in Science Journalism Intern.