NASA: Primitive Mars Ocean Had More Water Than Earth's Arctic Ocean

Posted on March 8, 2015

Ocean in Mars's northern hemisphere 4 billion years ago

NASA scientists say a primitive ocean on Mars had more water than Earth's Arctic Ocean. The scientists used ground-based observatories to measure water signatures in the Martian atmosphere. The scientists estimate that 4.3 billion years Mars likely had enough water to cover its entire surface in a liquid layer about 450 feet (137 meters) deep. The images above and below are an artists' impression of Mars four billion years ago.

The researchers say there was likely on ocean occupying almost half of Mars' northern hemisphere. It would have been deeper than a mile (1.6 kilometers) in some regions.

Geronimo Villanueva, a scientist at NASA's Goddard Space Flight Center and lead author of a new paper, says in a statement, "Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space. With this work, we can better understand the history of water on Mars."

The new estimate of ancient Mars' water is based on detailed observations of two slightly different forms of water found in the Martian atmosphere. One is the form of water most are familiar with, H2O, and the other is HDO, which is also known as semi-heavy water. HDO is a naturally occurring variation in which one hydrogen atom is replaced by a heavier form, called deuterium. Deuterated water is heavier than regular water and is less easily lost into space through evaporation than H20. The scientists say that the greater the water loss from the planet, the greater the ratio of HDO to H20 is in the remaining water.

The researchers studied the chemical signatures of H20 and HDO using ESO's Very Large Telescope and instruments at the W. M. Keck Observatory and the NASA Infrared Telescope Facility in Hawaii. The data indicates that atmospheric water in the near-polar region was enriched in HDO by a factor of seven relative to Earth's ocean water. This implies that water in Mars's permanent ice caps is enriched eight-fold. The scientists say this means Mars must have lost a volume of water 6.5 times larger than the present polar caps to provide such a high level of enrichment. The volume of the early ocean is estimated to have been at least 20 million cubic kilometers. The research say the ancient ocean on Mars would have covered 19% of the planet's surface. The Atlantic Ocean occupies 17% of the surface of the Earth.

Mars globe with an ocean from 4 billion years ago

A research paper on the study of the Martian atmosphere was published here in the journal, Science.

Images: ESO/M. Kornmesser/N. Risinger (

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