Ancient Rock Reveals Signs of Water on Mars
An ancient rock from a Martian meteorite that fell to Earth some 13 thousand years ago is finally revealing its secrets, astonishingly showing signs that there was once water on Mars, a new study says.
"Minerals within the meteorite hold a snapshot of the planet's ancient chemistry, of interactions between water and atmosphere," lead author Robina Shaheen said in a news release.
According to this ancient chemistry, though it was billions of years ago, water may have once washed across the Martian surface and gave rise to living organisms.
Designated ALH84001, scientists found this ancient meteorite - the oldest one we have from Mars - just 30 years ago in an Antarctic ice field. It's reportedly a chunk of solidified magma from a volcano that erupted four billion years ago, and contains globules of carbonates and other minerals that seeped through the rock's pores, likely from water.
Carbonates are made up of carbon and oxygen, and the source of both of these elements determines what isotopes are present. Scientists can then analyze the chemical signature these isotopes left behind to reveal how much water and ozone was present on Mars when they formed.
"When ozone reacts with carbon dioxide in the atmosphere, it transfers its isotopic weirdness to the new molecule," Shaheen explained. And the more water, the smaller the weird ozone signal.
According to the study, published in the journal PNAS, the research team measured a pronounced ozone signal in the carbonates within the meteorite, suggesting that water once existed on Mars. Though, that's not to say that our nearest neighbor harbored vast oceans like those on Earth. It was more likely that the early Martian landscape held smaller seas.
Their analysis also found that four billion years ago, carbonates were depleted in carbon-13 and enriched in oxygen-18, meaning Mars had much less carbon that it does today.
"We now have a much deeper and specific insight into the earliest oxygen-water system in the solar system," co-author Mark Thiemens said. "The question that remains is when did planets, Earth and Mars, get water, and in the case of Mars, where did it go?
Scientists believe that Mars' atmosphere was once thicker than it is now - a characteristic that would be required for liquid water to flow on the planet's chilly surface. NASA's MAVEN (Mars Atmosphere and Volatile Evolution) spacecraft, which launched in November 2013 and is currently orbiting around Mars, is on a mission to help solve the mystery of how the Red Planet lost most of its atmosphere.
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