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A new study has found that Mars is doomed to drought due to its small size.
Thanks to observations from robotic explorers like Curiosity and Backpacker Resolve, scientists know that in the past, liquid water once flowed on Mars: the Red Planet was once home to lakes, rivers, streams, and perhaps even a huge ocean that covered much of the northern hemisphere.
But this surface water disappeared about 3.5 billion years ago, lost in space. With a lot of Martian atmosphere. Scientists believe this dramatic climate change came after the Red Planet lost its global magnetic field, which shielded the air on Mars from charged particles from the Sun.
To belong to: Search for water on Mars (photos)
But this immediate cause was supported by more fundamental reasons, according to the new study: Mars is simply too small to hold surface water for the long term.
“The fate of Mars was determined from the start,” study co-author Kun Wang, associate professor of earth and planetary sciences at Washington University in St. Louis, said in a statement. Press. “There would likely be a minimum size requirement for rocky planets to contain enough water to support life and plate tectonics.” Scientists believe that this threshold is higher than that of Mars.
The study team – led by Zhen Tian, a graduate student from Wang’s lab – examined 20 Martian meteorites, which they selected to represent the overall makeup of the Red Planet. Researchers measured the abundance of different isotopes of potassium in these extraterrestrial rocks, which ranged in age from 200 million years to four billion years. (Isotopes are versions of an element that contain different numbers of neutrons in their atomic nuclei.)
Tian and his colleagues have used potassium, known by the chemical symbol K, as a tracer of “volatile” elements and compounds, such as water, which change to the gas phase at relatively low temperatures. They discovered that Mars lost more birds during its formation than Earth, which is about nine times the size of the Red Planet. But Mars has preserved its birds better than the moon and Earth’s asteroid, which are 530 kilometers wide. Vesta, and both are much smaller and drier than the Red Planet.
“Why there are so much less volatile elements and their compounds in divergent planets than in undifferentiated primordial meteorites is a long-standing question,” said Katharina Lueders, research professor of Earth Sciences, Katharina Lueders, Research Professor in Earth Sciences. . Earth and Planets at the University of Washington. advertising. (The term “differentiated” refers to the cosmic body whose interior is divided into different layers, such as the crust, mantle, and core.)
“The discovery of the relationship between K-isotopic structures and planetary gravity is a new discovery with important quantitative implications regarding when and how separate planets received and lost their birds,” Ludders said.
The new study, published online today (September 20) in the Proceedings of the National Academy of Sciences, and previous work suggests short stature is a double whammy on life. Bantam planets lose a lot of water during their formation and their global magnetic fields close relatively early, causing the atmosphere to thin. (In contrast, Earth’s global magnetic field remains strong, powered by a dynamo deep within our planet.)
Team members said the new work could have applications outside of our cosmic backyard as well.
“This study suggests that there is a very limited range of planet sizes, so they only have enough water but not too much to develop a habitable surface environment,” said co-author Klaus Mezger. , of the Space Center and Habitability at the University of Bern in Switzerland, in the same press release. “These findings will guide astronomers in their search for exoplanets in other solar systems.”
The warning “surface ecology” is important in any discussion of habitability. Scientists believe modern Mars is still home to vital aquifers, for example. And moons like Jupiter’s Europe and Saturn’s Enceladus harbor immense, perhaps even vital, oceans beneath their ice-covered surfaces.
Mike Wall is the author of “the least(Grand Central Publishing, 2018; illustrated by Karl Tate), A book about the discovery of extraterrestrial life. Follow him on twitter Integrated Tweet. Follow us on twitter Integrated Tweet or Facebook.
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