Water/ Climate change
Scientists comparisons
By comparing the ratio of HDO to H2O in water on Mars today
and comparing it with the ratio in water trapped in a Mars
meteorite dating from about 4.5 billion years ago, scientists can
measure the subsequent atmospheric changes and determine
how much water has escaped into space.
The team mapped H2O and HDO levels several times over
nearly six years, which is equal to approximately three Martian
years. The resulting data produced global snapshots of each
compound, as well as their ratio. These first-of-their-kind maps
reveal regional variations called microclimates and seasonal
changes, even though modern Mars is essentially a desert.
The research team was especially interested in regions near
Mars’ north and south poles, because the polar ice caps hold
the planet’s largest known water reservoir. The water stored there
is thought to capture the evolution of Mars’ water during the wet
Noachian period, which ended about 3.7 billion years ago, to
the present.
Early ocean
From the measurements of atmospheric water in the near-polar
region, the 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 told them how much
water Mars must have lost – a volume 6.5 times larger than the
volume in the polar caps now. That means the volume of Mars’
early ocean must have been at least 20 million cubic kilometres
(5 million cubic miles).
Based on the surface of Mars today, a likely location for this water
would be in the Northern Plains, considered a good candidate
because of the low-lying ground. An ancient ocean there would
have covered 19 percent of the planet’s surface. By comparison,
the Atlantic Ocean occupies 17 percent of Earth’s surface.
“With Mars losing that much water, the planet was very likely
wet for a longer period of time than was previously thought,
suggesting it might have been habitable for longer,” said Michael
Mumma, a senior scientist at Goddard and the second author on
the paper.
Studying
NASA is studying Mars with a host of spacecraft and rovers under
the agency’s Mars Exploration Program, including the Opportunity
and Curiosity rovers, Odyssey and Mars Reconnaissance Orbiter
spacecraft, and the MAVEN orbiter, which arrived at the Red
Planet in September 2014 to study the planet’s upper atmosphere.
In 2016, a Mars lander mission called InSight will launch to tak B