According to NASA scientists, the interior of Mars holds vasts reservoirs of water, “with some spots apparently as wet as Earth’s innards.” NASA’s Spirit and Opportunity rovers, which landed on the Red Planet in 2004, have found evidence that Mars used to be much warmer and had a surface covered in water billions of years ago. Continue reading for a video and more information.

The scientists examined two Martian meteorites that formed in the planet’s mantle, the layer under the crust. These rocks landed on Earth about 2.5 million years ago, after being blasted off the Red Planet by a violent impact.

Using a technique called secondary ion mass spectrometry, the team determined that the mantle from which the meteorites derived contained between 70 and 300 parts per million (ppm) of water. Earth’s mantle, for comparison, holds roughly 50-300 ppm water, researchers said.

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