Scientists of the National Aeronautics and Space Administration (NASA) suggest that Mars once had more water than the Arctic Ocean on Earth. They have come to that conclusion after measuring water signatures in the planet’s atmosphere using ground-based observatories.
Research has convinced NASA scientists that about 4.3 billion years ago, Mars had enough water to cover its entire surface in liquid as deep as approximately 450 feet (137 meters). However, they suggest that it is more likely that the water formed an ocean that covered almost half of the Red Planet’s northern hemisphere. They believe that in some regions the liquid had a depth of more than a mile (1.6 kilometers).
The conclusion is based on observations made at the European Southern Observatory’s Very Large Telescope in Chile, and the W.M. Keck Observatory and NASA’s Infrared Telescope Facility in Hawaii.
Using these facilities, researchers determined that there are chemical signatures for two slightly different forms of water in the Mars atmosphere – H2O and HDO. Of course H2O is the familiar chemical composition of water and HDO is a naturally occurring variation in which one-part hydrogen is replaced by deuterium, a heavier form of hydrogen.
Scientists compared the ratio of HDO to H2O in water on Mars today with the ratio in water trapped in a Mars meteorite dating from about 4.5 billion years ago. By making the comparison they can measure the subsequent atmospheric changes and determine how much water has escaped into space.
The researchers mapped H2O and HDO levels several times for about six years, which is equal to about three Martian years. The data was calculated and produced global snapshots of each compound as well as their ratio. Maps created as a result of the study show regional variations called microclimates had seasonal changes, regardless of the fact that Mars now is essentially a desert.
The research team focused on regions near the north and south poles of Mars because the polar ice caps hold the planet’s largest known water reservoir today. The water stored in those areas is said to capture the evolution of Mars’ water during the wet Noachian Period to the present. The Noachian Period ended about 3.7 billion years ago.
From the measurements of atmospheric water in the near-polar region, researchers determined the enrichment, or relative amounts of the two types of water, in the planet’s permanent ice caps. The enrichment of the ice caps showed that Mars lost a volume of water 6.5 times larger than the volume in the polar caps today. So, the volume of Mars’ early ocean must have been at least 5 million cubic miles (20 million cubic kilometers).
Based on the surface topography of Mars today, researchers guess that the most likely location for the water would be the Northern Plains. This region is considered a good candidate because of its low-lying ground. It is believed that an ancient ocean there would have covered 19 percent of the Planet’s surface. By comparison, the Atlantic Ocean covers 17 percent of the Earth’s surface.
Assuming that Mars did lose that much water, the planet was very likely wet for a longer period of time than was previously thought. This suggests that it might have been habitable for a longer period of time.
NASA is currently studying Mars with a plethora of spacecraft and rovers, including the Opportunity and Curiosity rovers, Odyssey and Mars Reconnaissance Orbiter spacecraft, and the MAVEN orbiter, which arrived at the planet in September 2014 to study the planet’s upper atmosphere.
NASA plans to launch a Mars lander mission called Insight in 2016 that will study the deep interior of Mars. The agency is also partnering with the European Space Agency (ESA) in ExoMars missions in 2016 and 2018. The 2018 mission will include a rover. NASA plans to put another rover on the Red Planet in 2020.