Researchers have determined that a primitive ocean on Mars may have once held more water than is currently found in Earth’s vast Arctic Ocean. This paints a very different picture from the dusty Red Planet that we know today, and raises questions about where all that water could have gone.
About four billion years ago, Mars would have had enough liquid water to cover its entire surface in a liquid layer about 140 meters deep. It’s far more likely, though, that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere.
“Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space,” said Geronimo Villanueva, one of the researchers, in a news release. “With this work, we can better understand the history of water on Mars.”
Interestingly, that doesn’t mean that the young Mars was a beautiful water-land. Instead, it was likely a world of contrasts, where a vast singular ocean likely occupied the great majority of its northern hemisphere. There, some portions of the ocean would have reached as deep as a mile or more, even while the southern side of the planet remained largely dry or even volcanic – with lava actually carving some of the canyons we see there.
The research itself was conducted by a team comprised of NASA planetary scientists and astrobiologists. It was done by comparing maps of H20 and HDO(a “heavier” form of water in which a hydrogen isotope called deuterium replaces one of the normal ones) traces found on the planet’s surface and atmosphere, with high concentration of either hydrogen or deuterium being indicative of previous water loss.
Samples found caught in the planet’s atmosphere were especially conclusive, as it is expected that the drying of Martian water mass resulted in traces of it ascending from its surface.
Data from the research was obtained from observations of Mars with several high-power large telescopes and samples obtained by the Curiosity rover, stationed on the planet since 2011.
Based on the surface of Mars today, a likely location for this water would be the Northern Plains, which have long been considered a good candidate because of their low-lying ground. An ancient ocean there would have covered 19% of the planet’s surface — by comparison, the Atlantic Ocean occupies 17% of the Earth’s surface.
“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, a senior scientist at Goddard and the second author on the paper.
The search for life on Mars will ramp up in 2018 when the European Space Agency sends its Exomars rover to the red planet. The rover will look for chemical signatures of life, perhaps emanating from microbes living deep beneath the Martian soil.