(NEWSER) – Imagine all the water in the Arctic Ocean. Now, imagine all that and more on Mars. If you visited the Red Planet roughly 4.3 billion years ago, that's what you likely would have found, say NASA scientists. Their new study arrived at that "solid estimate ... by determining how much water was lost to space," says lead author Geronimo Villanueva.
The Guardian reports the scientists used three powerful infrared telescopes to analyze two forms of water in Mars' atmosphere: H2O and HDO, in which deuterium (aka "heavy" hydrogen) has taken the place of one hydrogen atom. As National Geographic explains, Mars' gravity is weaker than our own; that allowed hydrogen to escape from the atmosphere and into space over time, boosting the amount of deuterium in its water. Scientists compared the ratio of HDO to H2O in Martian water today with that in water from a 4.5 billion-year-old Mars meteorite to arrive at their conclusions, a press release states.