Mars was once covered by a massive ocean, NASA scientists say

(Image credit: NASA/YouTube)

published 6 March 2015

About 4.3 billion years ago, up to 20 percent of Mars was covered by an ocean that reached about a mile in depth, according to scientists from NASA's Goddard Space Flight Center. The polar ice caps today contain the 13 percent of that ocean that didn't evaporate into space when Mars' atmosphere largely disappeared.

Scientists already knew that Mars once had water, but this extends the red planet's wet period for much longer. "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 Goddard's Michael Mumma, another author of the report. Mumma and Villanueva explain their research and its implications in greater detail in the NASA video below. —Peter Weber

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Peter has worked as a news and culture writer and editor at The Week since the site's launch in 2008. He covers politics, world affairs, religion and cultural currents. His journalism career began as a copy editor at a financial newswire and has included editorial positions at The New York Times Magazine, Facts on File, and Oregon State University.

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