These days, not so much. But more than 4.5 billion years ago, the Red Planet may have had a crust comparable to today’s Iceland. This discovery, hidden in the oldest Martian fragments found on Earth, could provide information about our planet that has been lost over billions of years of geological movement and could help explain why Earth developed into a planet. which supports a great diversity of life and Mars did not.
This information about Earth’s past comes from a new study, published today in Communication Nature, by an international team that includes a researcher from the NAU. The study details how they found the probable Martian origin of the 4.48 billion year old meteorite, unofficially named Black Beauty. Its origin is one of the oldest regions of Mars.
“This meteorite recorded the first step in the evolution of Mars and, by extension, of all terrestrial planets, including Earth,” said Valérie Payré, postdoctoral researcher in the Department of Astronomy and Planetary Sciences. “While the Earth has lost its old surface primarily through plate tectonics, observing such parameters in extremely old terrain on Mars is a rare window into the old Earth surface that we lost there. for a long time. »
What Mars can tell us about Earth
The team, led by Anthony Lagain of Curtin University in Australia, searched for the place of origin of a Martian meteorite (officially named NWA – North West Africa – 7034 for where it was found on Earth). This meteorite, whose chemistry indicates that Mars had volcanic activity to that found on Earth, recorded the first stage of Mars’ evolution. Although it was ejected from the surface of Mars 5 to 10 million years ago after an asteroid impact, its region of origin and geological context have remained a mystery.
This team studied the chemical and physical properties of Black Beauty to determine its origin. they determined that it came from Terra Cimmeria-Sirenum, one of the oldest regions of Mars. It may have a surface area similar to the continents of Earth. Planetary bodies like Mars have impact craters all over their surface, so finding the right one is difficult. In a previous study, Lagain’s team developed a crater detection algorithm that uses high-resolution images of the surface of Mars to identify small impact craters, finding about 90 million as small as 50 meters in diameter. In this study, they were able to isolate the most plausible ejection site – the Karratha crater which excavated ejecta from an older crater named Khujirt.
“For the first time, we know the geological context of the only Martian brecciated sample available on Earth, 10 years before NASA’s Mars Sample Return mission was scheduled to return samples collected by the Perseverance rover currently exploring Jezero Crater.” , said Lagain. , a researcher at Curtin’s School of Earth and Planetary Sciences. “This research paved the way for locating the ejection site of other Martian meteorites, to create the most comprehensive view of the Red Planet’s geological history. »
Payré studies the nature and formation of the crust of Mars to determine if Earth and Mars share a common past that includes both continental and oceanic crust. She uses orbital observations captured in this region to determine if traces of volcanism similar to Iceland exist on Mars.
“To date, the complexity of Mars’ crust is not understood, and knowing the origin of these amazing ancient fragments could lead future rover and space missions to explore the Terra Sirenum-Cimmeria region that hides the truth. of the evolution of Mars, and perhaps the evolution of Earth,” she said. “This work paves the way for locating the ejection site of other Martian meteorites that will provide the most comprehensive view of the geological history of Mars and answer one of the most intriguing questions: why does Mars, now dry and cold, evolved so differently from Earth, a planet thriving for life? »
The team’s algorithm is suitable for detecting impact craters constellating Mercury and the Moon, other terrestrial bodies. This can be used to help unravel their geographic history and answer fundamental questions about their formation and evolution. This work is a starting point to guide future investigations of the solar system.