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NASA Study Suggests Early Mars Once Had a Vast Ocean

water on Mars

Image credit: NASA/GSFC

With six-year observation of atmosphere and recording of water signatures of the Mars, scientists have found it strongly evident that early Mars not only had a much wetter world than they thought before, but also owned a huge northern ocean consisting of a fifth of its surface. The size of this vast area of water would be similar to that of the Arctic Ocean and it had lasted for millions of years, which might be long enough for life to have had an opportunity for evolution. These latest findings have been released in the recent edition of Science.

While observational techniques have been advanced for the past years, our understanding of the history of the Red Planet has become much better. According to our previous observation, most of ancient Mars was thought to be quite barren; therefore, flowing water seemed to be sporadic and never hanged around for a long time so as to form remarkable long-lasting pools. However, the picture of young Mars as a parched, inhospitable place is slowly changed to the one that was much wetter, having meandering rivers and enduring lakes. For instance, based on the new evidence collected by NASA’s Curiosity rover, it was suggested that the Gale Crater was full of water lingering for millions of years.

However it was still doubted how these lakes were filled. There should exist a active hydrological cycle to allow the atmosphere to be moist enough. If there was no a huge body of water to enable everything to remain humid, water would have left to be evaporated or frozen out very quickly. Due to these reasons scientists assumed that the existence of oceans must have been there in the early days of Mars.

While these lakes are dehydrated at present, by identifying the amount of water was lost to space; scientists could make the estimation of how much water the Mars held in its early times. That is exactly what NASA and ESO scientists have been making efforts to know over the past six years, which is helped with a trio of observatories based on ground.

In order to find out more, scientists had made measurement of the amounts of two different forms of water in the atmosphere of Mars. One was H2O, the familiar type known to us, whereas the other was known as HDO, a naturally occurring heavier version in which one of the hydrogen atoms was replaced by a lightly different form called deuterium. While most hydrogen atoms were composed by one proton and one electron, deuterium also had a neutron.

Compared with HDO, H2O was lighter; in that case, if water was lost to space, H2O would be preferentially lost. It meant that the concentration of deuterium in water left behind goes up. Therefore, by examining the ratio of HDO to H2O in water on current Mars and comparing it with the ratio discovered in Martian meteorites which could be traced back to some 4.5 billion years, scientists could identify the amount of water had been evaporated into space during such a long period of time.

On the basis of such data, it was estimated by scientists that in the early days there would be sufficient water to cover the total surface of Mars with a layer that was 137 meters deep. However, the more possible assumption would be that Mars had a huge ocean occupying more than half of the northern hemisphere, in another word, covering 19% of the surface of the planet, where some area could be a mile deep.

As Michael Mumma, study author said, when Mars had lost water to this extent, it could be possible that the planet used to be wet for a longer period of time than scientist thought before, thus demonstrating that Mars could have been habitable for longer.

[Via ScienceNASAThe New York Times and the Guardian]