article_snippet: (CNN)Scientists at NASA are one step closer to understanding how much water could have existed on MarsMars.
article_snippet: These new findings also indicate how primitive water reservoirs there could have evolved over billions of years, indicating that early oceans on the Red Planet might have held more water than Earth's Arctic Ocean, NASA scientists reveal in a study published Friday in the journal Science.
article_snippet: "a study published Friday in the journal Science provides a solid estimate of how much water Mars once had, by determining how much water was lost to space," said Geronimo Villanueva, a scientist at NASA's Goddard Space Flight Center.
article_snippet: With this work, we can better understand the history of water on Mars.
article_snippet: To find answers to this age-old question about Martian water molecules, scientists used the world's three major infrared telescopes, in Chile and Hawaii, to measure traces of water in the Red Planet's atmosphere over a range of areas and seasons, spanning from March 2008 to January 2014.
article_snippet: Scientists looked at the ratio of two different forms -- or isotopes -- of water, H2O and HDO.
article_snippet: That weighed down HDO more, while larger amounts of hydrogen from H2O floated into the atmosphere, broke away from Mars' low gravity and disappeared into space.
article_snippet: As a result, water trapped in Mars' polar ice caps has a much higher level of HDO than fluid water on Earth does, Scientists said.
article_snippet: Scientists compared the ratio of H2O to HDO in Mars' atmosphere today to the ratio of the two molecules trapped inside a Mars meteorite, a stone that broke off from Mars -- perhaps when an asteroid hit -- and landed on Earth some 4.5 billion years ago.
article_snippet: Scientists were able to determine how much that ratio had changed over time and estimate how much water has disappeared from Mars -- about 87%.
article_snippet: The findings indicate that the Red Planet could have had the Red Planet fair share of blue waters, possibly even yielding an ocean.
article_snippet: According to NASA, there might have been enough water to cover up to 20% of Mars' surface.
article_snippet: NASA scientists say that much of this water loss happened over billions of years, along with a loss of atmosphere.
article_snippet: And as the Red Planet's atmospheric pressure dropped, it was harder for water to stay in liquid form.
article_snippet: With Mars losing that much water, the Red Planet was very likely wet for a longer period of time than was previously thought, suggesting the Red Planet might have been habitable for longer," said Mumma.
highlights_snippet: Scientists studied water in Mars' atmosphere with three giant infrared telescopes .
  
highlights_snippet: Scientists compared the ratio of certain molecules on the Red Planet with that of a Mars meteorite that landed on Earth .