Scientists May Have Identified the Crater on Mars that Launched a Rock to Earth

National Geographic reports: About a million years ago, an asteroid smacked into the normally tranquil surface of Mars. The impact released a fountain of debris, and some of the rocky fragments pierced the sky, escaping the planet's gravity to journey through the dark. Some of the rocks eventually found their way to Earth and survived the plunge through our planet's atmosphere to thud into the surface-including a hefty 15-pound shard that crashed into Morocco in 2011.... Determining what part of Mars these meteorites came from is a critical part of piecing together the planet's history — but it's proven to be a major scientific challenge. Now, with the assistance of a crater-counting machine learning program, a team of researchers studying the depleted shergottites may have finally cracked the case: They concluded that these geologic projectiles came from a single crater atop Tharsis, the largest volcanic feature in the solar system. This ancient volcanic behemoth on Mars is adorned with thousands of individual volcanoes and extends three times the area of the continental United States. It was built over billions of years by countless magma injections and lava flows. It is so heavy that, as it formed, it effectively tipped the planet over by 20 degrees. If these meteorites do come from Tharsis, as the analysis published in Nature Communications suggests, then scientists have their hands on meteorites that can help identify the infernal forces that fueled the construction of this world-tipping edifice. "This could really change the game about how we understand Mars," says Luke Daly, a meteorite expert at the University of Glasgow who was not involved with the study. Debris from meteor impacts tend to also form smaller craters — so the scientists trained their machine learning tools to scan orbital images of Mars to find appropriately-sized crazers (less than two thirds of a mile long). "It quickly found about 90 million, says Kosta Servis, a data scientist at Curtin University and co-author of the study..." But after sifting through the data, "the team identified 19 large craters in volcanic regions on Mars that were surrounded by multiple secondary craters — a sign that these planetary scars could be as young as the 1.1-million-year-old crater they sought..." Out of those 19 craters, just two were excavated from youthful volcanic deposits by an impact event 1.1 million years ago: crater 09-00015 and Tooting crater. The latter (named after a district in London) looks to have been formed by a powerful oblique impact — the kind of collision that would propel a lot of Martian meteorites into space..." Buoyed by their discovery, Lagain's team is hoping to identify the source craters of other Martian meteorites — including some of the very oldest, which could reveal more about Mars's waterlogged past.... Machine learning "is a really inventive way of trying to tackle this problem," says Lauren Jozwiak, a planetary volcanologist at Johns Hopkins University Applied Physics Laboratory not involved with the study. "Boy, I hope this method works," she says, because if it does, "it would be really cool to take this and apply it to other planets."

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