Oceans
of water in Mars?
Mars Has “Oceans” of Water Inside?
And volcanoes flooded early Mars with H2O,
meteorite study hints. Water on
Mars exists almostexclusively as water
ice. Mars could have entire oceans’ worth of water locked in rocks deep
underground, scientists say.
The finding suggests that ancient volcanic eruptions may have been major sources of
water on early Mars—and could have created habitable environments.
According to a new
study, Martian
meteorites contain a surprising amount of hydrated minerals,
which have water incorporated in their crystalline structures.
In fact, the study authors estimate that the Martian mantle currently
contains between 70 and 300parts per million of water—enough
to cover the planet in liquid 660 to 3,300 feet (200 to 1,000 meters)
deep.
“Basically the amount of water we’re talking about is equal to or
more than the amount in the upper mantle of the Earth,” which
contains 50 to 300 parts per million of water, said study leaderFrancis McCubbin,
a planetary scientist at the University of New
Mexico in Albuquerque.
And if water exists today in the Martian mantle, that means the red planet likely
had a lot of water in its interior all the way back to the moment the planet
formed.
“We don’t have to rely on sources like comets and asteroids to bring
in water afterward,” McCubbin said.
And if that’s the case for Mars, it’s
probably the case for the other rocky planets—Mercury, Venus, and Earth—as well
as for some large asteroids.
“Earth is not unique,” McCubbin said. “We should be finding water nearly
everywhere in the solar system.”
Water Boiled Out of Mars Lava
McCubbin’s team found water while analyzing meteorites that had been
blasted off the Martian surface by asteroid impacts and sent careening to
Earth.
The meteorites are basaltic, which means the rocks must have formed
from deep magmas brought to the surface during volcanic eruptions.
By carefully examining a mineral called apatite, McCubbin’s
team found hydroxyl ions—a form of water that contains an oxygen atom bound
to a hydrogen atom.
The presence of hydroxyl means that standard water—oxygen bound to two
hydrogens—was also present in Martian magma. But because the hydroxyl
is more tightly bound to rock than ordinary water, the
ions remained behind when the rest of the water boiled out of the coolinglava.
From the amount of hydroxyl in the meteorites, it’s possible to
reconstruct how much water is in Mars’s interior, McCubbin added.
“We’re using apatite as a hydrometer to record how much
water was in the rock before it degassed,” he said. For instance, similar
studies of lunar apatite in
2010 found that the moon’s interior is a hundred times wetter than previously
thought.
Furthermore, he said, the Mars meteorites examined in the new study
came from extremely young basalts, only 150 to 350 million years old.
That means all large Martian eruptions throughout the planet’s history probably
carried substantial water to the surface—including eruptions that happened during
the Noachian, the period when ancient
Mars was warm enough
to have possibly hosted liquid water on the surface.
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