NASA scientists measuring water signatures in Mars’ atmosphere have found evidence to suggest the Red Planet once possessed a vast ocean of water.
The researchers used ground-based observatories to determine a “solid estimate” of the quantity of water, which has since been “lost to space”.
The NASA study compared the ration of H2O and HDO (a form of heavy water) on Mars today to the ratio of water trapped in a Mars meteorite from about 4.5 billion years ago. Atmospheric changes and water levels were measured several times over a period of almost six years to work out how much water has disappeared.
Perhaps about 4.3 billion years ago, Mars would have had enough water to cover its entire surface in a liquid layer about 450 feet (137 metres) deep. More likely, the water would have formed an ocean occupying almost half of Mars’ northern hemisphere, in some regions reaching depths greater than a mile (1.6 kilometres).
Mars’ polar ice caps hold the planet’s largest known water reservoir. From the atmospheric measurements recorded in these regions, the researchers were able to determine the relative amounts of H20 and HDO retained in the planet’s ice caps and how much water Mars must have lost during the wet Noachian period, which ended 3.7 billion years ago.
The analysis established there would have been a volume of at least 20 million cubic kilometers – 6.5 times more than current estimates.
The planet’s Northern Plains are considered to be one of the likely locations for this lost ocean. The low-lying ground levels would have meant the primitive ocean would have covered almost 20% of the Mars’ surface. By comparison, the Atlantic Ocean occupies 17 percent of Earth’s surface.
Michael Mumma, a senior scientist at NASA’s Goddard Space Flight Centre said, “With Mars losing that much water, the planet was very likely wet for a longer period of time than was previously thought, suggesting it might have been habitable for longer.”
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