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A mineral trapped in a Martian meteorite that fell to Earth has revealed traces of water on Mars dating back 4.45 billion years, new research shows. Zircon grain may contain oldest direct evidence of ancient hot water on the red planetwhich may have provided environments such as hot springs associated with life on Earth.
This discovery opens new avenues for understanding whether Mars was habitable in its ancient past. It also adds more support to observations already collected by the fleet of spacecraft orbiting and roaming the Red Planet, which have spotted evidence of where rivers and lakes once existed on the Martian surface.
But key questions remain about when exactly water first appeared on Mars and how it evolved – and disappeared – over time.
Scientists have analyzed a sample of the “Black Beauty” meteorite, also known as NWA 7034, found in the Sahara Desert in 2011. The meteorite was ejected from the Martian surface after another celestial object struck the planet between 5 and 10 million years ago. a few years ago, and fragments of it served as a key source for the study of ancient Mars.
The new study, published in the journal Scientific advances on November 22, focused on a single grain of the mineral zircon spotted in the meteorite. The team’s analysis shows that water was present only 100 million years after the planet’s formation, suggesting that Mars could have supported life at some point in its history.
“Our data suggest the presence of water in the crust of Mars at a time comparable to that of Mars. the first evidence of water on the Earth’s surfaceabout 4.4 billion years ago,” said the study’s lead author, Jack Gillespie, a researcher at the Faculty of Geosciences and the Environment at the University of Lausanne in Switzerland, in a statement “This discovery provides new evidence for understanding the planetary evolution of Mars, the processes that took place there and its potential to support life.”
The rocks could hold the answers to some of the biggest remaining questions on Mars, including how much water is present and whether there is life on the planet. This is why meteorites like Black Beauty are of so much interest to scientists. Carl Agee, professor and director of the Meteoritics Institute at the University of New Mexico, first introduced the space rock to the scientific community in 2013.
“(The Black Beauty meteorite) contains hundreds of rock and mineral fragments, each representing a different part of 4.5 billion years of Martian history,” said study co-author Dr. Dr Aaron Cavosie, planetary scientist and lecturer at the Center for Space Science and Technology. at Curtin University, in an email. “(It is) the only source of pieces for the geological puzzle of pre-Noachian Mars.”
The Noachian period occurred between 4.1 and 3.7 billion years ago, and little is known from direct measurements dating to the pre-Noachian period on Mars, between 4.5 and 4.1 billion years, although it is crucial to understand as this serves as the first page. in the Mars history book, Cavosie said.
But Black Beauty has revealed some of its secrets. Many of the rock fragments contained in the meteorite show that the Martian crust suffered a number of impacts, causing enormous upheavals on the planet’s surface, he said.
The space rock also contains the oldest known pieces of Mars, including the oldest zircons, Cavosie said.
Zircon, used in products such as jewelry, ceramic tiles and medical implants, is a robust mineral that can help scientists look into the past and determine the conditions present when it crystallized, including the temperature at that time and whether the mineral has interacted with the water.
“Zircon contains traces of uranium, an element that acts like a natural clock,” said Gillespie, who was a postdoctoral researcher in Curtin University’s School of Earth and Planetary Sciences at the time of the study. “This element decays to lead over time, at a precisely known rate. By comparing the uranium/lead ratio, we can calculate the age of crystal formation.
Black Beauty’s zircon was unaltered by its journey to Earth and fiery entry into our planet’s atmosphere before crashing into the Sahara, because it was protected by its location inside the meteorite , Cavosie said.
When analyzing the zircon grain, the study team detected unusual amounts of iron, sodium and aluminum, suggesting that water-rich fluids left these traces on the zircon as it was processed. formation 4.45 billion years ago. Such elements are not usually found in crystalline zircon, but the researchers’ studies of zircon at the atomic scale showed that the elements were embedded in the crystal structure and lined up like fruit stands at a market, a said Cavosie.
“We could tell from the patterns of iron, aluminum and sodium inside the zircon that they were incorporated into the grain as it grew, like the layers of an onion,” Cavosie said.
On Earth, zircons from hydrothermal systems – which form when water is heated by underground volcanic activity like the upward flow of hot magma – have patterns similar to those found in Black Beauty.
If hydrothermal systems existed in the Martian crust 4.45 billion years ago, liquid water would likely have risen to the surface.
“Our experience on Earth shows that water is essential for habitats capable of supporting life,” Cavosie said. “Many environments on Earth support life in hot water systems, including hot springs and hydrothermal vents. Such environments may have given rise to the first forms of life on Earth. Our new study shows that Mars’ crust was warm and moist in pre-Noachian times, meaning habitable environments may have existed at that time.
Cavosie is curious to determine whether hydrothermal systems such as hot springs were prevalent when magma helped form the crust of the Red Planet between 4.48 billion and 4.43 billion years ago or if they were more episodic.
“If hydrothermal systems were a stable feature in early Mars, that would indicate that habitable conditions may have persisted for a considerable period of time,” Cavosie said. “This is now a testable hypothesis that can be resolved by collecting more data on Martian zircons.”
Until samples can be sent back directly from Mars, the Black Beauty meteorite is one of the best windows into how the Martian crust formed and what the first surface of Mars looked like, Briony Horgan said. , co-investigator of the Perseverance rover mission and professor of planetary sciences at Purdue University in West Lafayette, Indiana. Horgan was not involved in this study.
Finding evidence of hydrothermal systems underground from a tiny grain of zircon aligns with scientific theories about the amount of water and volcanic activity that existed on ancient Mars, he said. she declared. And these early potentially habitable environments would have been protected from radiation by a strong planetary magnetic field, something Mars lacks today, Horgan added. Scientists are still trying to explain how the Red Planet lost its protective magnetic field.
Currently, the Perseverance rover is climb the rim of Jezero Crater on Mars, an ancient lake filled with water 3.7 billion years ago. Some of the rocks the rover encountered could have been formed by hydrothermal systems, Horgan said.
The rover will collect rock samples because they could preserve evidence of ancient microbial life.
“As much as meteorites can tell us, we can do even better with a carefully selected, intact rock sample from a known location on Mars with good geological context,” Horgan said. “This article therefore provides great motivation to bring our samples from Mars back to Earth to study them with the same level of detail in the years to come.”