Vast Ocean Once Covered Mars' Surface, NASA Study Shows

is there life on mars? idk bowie
NASA’s Hubble Space Telescope snapped this portrait of Mars within minutes of the planet’s closest approach to Earth in nearly 60,000 years, on August 27, 2003. Reuters

David Bowie may have been onto something when he sang about "life on Mars": A new NASA study has unearthed strong evidence that almost half of the planet's northern hemisphere was once covered by a vast ocean. If confirmed, this evidence would strengthen the theory that Mars possibly sustained life.

"With Mars losing that much water, the planet was very likely wet for a longer period of time than previously thought, suggesting the planet might have been habitable for longer," said Michael Mumma, an author of the new study.

The researchers, who published their findings Thursday in the journal Science, have long speculated that Mars once had a sizable surface ocean. The study adds to the discoveries from NASA's Curiosity rover—which helped determine that Mars was a watery planet 1.5 billion years ago—and suggests that the body of water was much larger than researchers had previously thought, perhaps even the size of Earth's Arctic Ocean, and almost a mile deep.

As part of the study, researchers used three infrared telescopes to map the water molecules present in Mars's atmosphere. They found both H20 and HDO molecules, the latter of which is "heavier" than our beloved water molecule, as it contains an atom called deuterium. The two kinds of molecules also have been detected on Martian meteorites, as well as on Earth. The atmosphere of Mars contains eight times more deuterium that Earth's.

When studying the northern and southern poles of Mars, researchers discovered large quantities of deuterium. They now believe the planet once contained 6.5 times more water than is currently in its polar ice caps.

Researchers are unsure how the icy planet could have been warm enough for its surface ocean to remain liquid. One theory is that greenhouse gases were a contributing factor.

Also, it's still an open question as to whether life once existed on the Red Planet, and it's unclear how Mars could have lost so much water. Researchers speculate that the ocean dissolved when Mars's atmosphere changed over the course of billions of years.