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We know Mars used to be much wetter than it is now, but the questions of when water formed and evaporated are much harder to answer.
A new study now suggests that water was present on the Red Planet some 4.4 billion years ago, much earlier than previously thought.
This is based on an analysis of a meteorite called NWA 7533, collected in the Sahara Desert and thought to have originated on Mars billions of years ago. The oxidation of some minerals inside the meteorite suggests the presence of water.
The findings could delay the estimated date of water formation on Mars by about 700 million years, compared to the 3.7 billion-year period that has been the general consensus until now. The research could also offer some insight into how planets are formed in the first place.
“I study minerals in Martian meteorites to understand how Mars formed and how its crust and mantle evolved,” says planetary scientist Takashi Mikouchi of the University of Tokyo in Japan.
“This is the first time I have investigated this particular meteorite, nicknamed ‘Black Beauty’ due to its dark color. Our samples of NWA 7533 have undergone four different types of spectroscopic analysis, methods for taking chemical fingerprints. The results. have led our team to draw some exciting conclusions. “
Planetary scientists are very interested in the history of water on planets and moons. One of the big unknowns is whether water is added to a planetary body after it is formed, through the impacts of asteroids and comets, or whether it occurs naturally during the planet’s formation process.
Ancient rocks like NWA 7533 can help scientists peer back in time and find out, as they record impact events on the planet they come from and capture some of the surface’s mineral and chemical composition as they form.
In this case, oxidation is the telltale sign of water. With some fragments inside NWA 7533 dated to 4.4 billion years ago, it is the oldest record we have of Mars (which may be why a single gram of this meteorite can be worth up to $ 10,000) .
“The igneous clasts, or fragmented rock, in the meteorite are formed from magma and are commonly caused by impacts and oxidation,” Mikouchi says. “This oxidation could have occurred if water was present on or in the Martian crust 4.4 billion years ago during an impact that melted some of the crust.”
Such an early appearance suggests that water was actually present when Mars formed and that in turn plays into the research on planetary formation in general. Life is born with water, which is one of the reasons scientists are so eager to track it down in the Universe. For comparison, we know that the first traces of life on Earth date back to at least 3.5 billion years ago.
The in-depth study of Mars continues as experts try to figure out when water was present and what shape it could have taken. A recent study has advanced the idea that both liquid water and surface ice could have existed simultaneously on the red planet.
The team’s findings also suggest that the chemical makeup of the Martian atmosphere at this time – including the high levels of hydrogen – could have made the planet warm enough to melt water and the existence of life, even though the Sun would be been younger and weaker during this period.
“Our analysis also suggests that such an impact would have released a lot of hydrogen, which would have contributed to planetary warming at a time when Mars already had a thick, insulating atmosphere of carbon dioxide,” Mikouchi says.
The research was published in Advances in science.
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