A primitive ocean on Mars held more water than Earth’s Arctic Ocean, according to NASA scientists who, using ground-based observatories, measured water signatures in the Red Planet’s atmosphere.
Scientists have been searching for answers to why this vast water supply left the surface. Details of the observations and computations appear in Thursday’s edition of Science magazine.
“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, a scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the new paper. “With this work, we can better understand the history of water on Mars.”
Perhaps about 4.3 billion years ago, Mars would have had enough water to cover its entire surface in a liquid layer about 450 feet (137 meters) deep. More likely, the water would have formed an ocean occupying almost half of Mars’ northern hemisphere, in some regions reaching depths greater than a mile (1.6 kilometers).
The new estimate is based on detailed observations made at the European Southern Observatory’s Very Large Telescope in Chile, and the W.M. Keck Observatory and NASA Infrared Telescope Facility in Hawaii. With these powerful instruments, the researchers distinguished the chemical signatures of two slightly different forms of water in Mars’ atmosphere. One is the familiar H2O. The other is HDO, a naturally occurring variation in which one hydrogen is replaced by a heavier form, called deuterium.
NASA’s Mars Exploration Program seeks to characterize and understand Mars as a dynamic system, including its present and past environment, climate cycles, geology and biological potential. In parallel, NASA is developing the human spaceflight capabilities needed for future round-trip missions to Mars in the 2030s.