The red, dry dust of
The ancient ocean may have been a mile deep in some places, not as deep as the deepest oceans on Earth, but comparable to the average depth of the Mediterranean Sea, according to Geronimo Villanueva, a scientist at NASA’s Goddard Space Flight Center and lead author of a paper on the findings that appears in this week's Science magazine.
Over the course of billions of years, Mars gradually lost its atmosphere, which led to a loss of heat and pressure that allowed as much as 87 percent of Martian water to escape the planet's surface. What remains today froze in place over the north and south poles to form the ice caps that are visible today.
The findings are based on observations by powerful telescopes here on Earth of the chemical signatures of two forms of water in the Martian atmosphere (H20 and the slightly different but naturally occurring HDO). The ratio of the two forms was then compared to the same ratio present in 4.5 billion year-old Martian meteorite to determine how much water has escaped the surface of the red planet in that time period. That amount turned out to be 6.5 times more than what is currently stored in the planet's ice caps.
“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,” said Michael Mumma, a senior scientist at Goddard and the second author on the paper.
More robotic landings are planned for Mars to probe deeper into the planet's past over the next five years, followed by possible manned NASA missions to the red planet in the 2030s. Get more details on the new research in the video below.
