Mars gateway to Earth's early evolutionary history: research

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Washington, Nov 26 (UNI) Earth and Mars may have remained molten in their early histories for tens of millions of years, says a recent research at NASA's Johnson Space Center (JSC) and the Lunar and Planetary Institute and the University of California, Davis (UCD).

The new data reveals that the early histories of the inner planets in the solar system are complex and involve processes no longer observed. Mars is probably the best opportunity to understand earth as the evidence of these processes has been preserved in Mars, while it has been erased in Earth.

The findings explain that the two planets cooled slower than scientists thought and a mechanism to keep the planet interiors warm is required.

The formation of the solar system can be dated quite accurately to 4,567,000,000 years ago, said Qing-Zhu Yin, assistant professor of geology at UC Davis and an author on a new paper. Mars' metallic core formed a few million years after that. Previous estimates for how long the surface remained molten ranged from thousands of years to several hundred million years.

The persistence of a magma ocean on Mars for 100 million years is ''surprisingly long,'' Mr Yin said. It implies that at the time, Mars must have had a thick enough atmosphere to insulate the planet and slow down cooling, he said, reported Science Daily.

Scientists feel that early crust formation alone cannot account for the slow cooling magma ocean seen in large planets. This new evidence indicates the presence of a primitive atmosphere in Mars once upon a time that acted as the insulator.

The primitive atmosphere was composed mostly of hydrogen left over from accretion into a rocky planet, but it was lost due to effects, about 100 million years after the planet finally took shape, said Vincaine Debaille one of the scientists who conducted the research.

''These rocks were lavas that were made by melting deep in Mars and then erupted on the surface,'' added another. They were delivered to Earth as meteorites following impacts on Mars that exhumed them and launched them into space.'' he concluded.

Mars meteorites are a treasure chest of information about that planet and have been the focus of extensive research by scientists.

The metallic element samarium has two radioactive isotopes that decay at a known rate to two daughter neodymium isotopes. By precisely measuring the quantities of neodymium isotopes, Mr Debaille was able to use these two radiometric clocks to derive the times of formation of the different shergottite sources in the Martian interior.

Ms Vincaine Debaille, Mr Alan Brandon and their colleagues who are working on the research found that the scenario that best fits the data is one where a global-scale magma ocean formed from melting in Mars during the final stages of accretion and then slowly solidified over this time period.

''The most recent physical models for magma oceans suggest they solidify on timescales of a few million years or less, so this result is surprising,'' said Mr Brandon. Some type of insulating blanket, either as a rocky crust or a thick atmosphere, is needed as an insulator to have kept the Martian interior hot.

UNI

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