by University of Texas
A vertically exaggerated view of Mars' north polar cap.
Researchers with The University of Texas at Austin
and the University of Arizona estimate that if melted,
the massive ice deposits discovered in this region would
cover the planet in 1.5 meters (5 feet) of water.
Credit: SA/DLR/FU Berlin; NASA MGS MOLA Science Team
Newly discovered layers of ice buried a mile beneath Mars' north
pole are the remnants of ancient polar ice sheets and could be one
of the largest water reservoirs on the planet, according to
scientists at The University of Texas at Austin and the University
The team made the discovery using measurements gathered by the
Shallow Radar (SHARAD) on NASA's Mars Reconnaissance Orbiter (MRO).
SHARAD emits radar waves
that can penetrate up to a mile and a half beneath the surface of
The findings, published May 22 in Geophysical Research Letters, are
important because the layers of ice are a record of past climate on
Mars in much the same way that tree rings are a record of past
climate on Earth.
Studying the geometry and
composition of these layers could tell scientists whether climate
conditions were previously favorable for life, researchers said.
The team found layers of
sand and ice that were as much as 90% water in some places.
If melted, the newly discovered polar ice would be equivalent to a
global layer of water around Mars at least 1.5 meters (5 feet) deep.
"We didn't expect to
find this much water ice here," said lead author Stefano Nerozzi,
a graduate research assistant at the University of Texas
Institute for Geophysics (UTIG)
who is completing his Ph.D. at the Jackson School of
"That likely makes it
the third largest water reservoir on Mars after the polar ice
A view of Mars showing the planet's northern polar ice cap.
A new study led by The University of Texas at Austin
has found remnants of ancient ice caps buried
the north polar region.
Credit: ISRO/ISSDC/Emily Lakdawalla
The findings were corroborated by an independent study using gravity
data instead of radar, led by researchers at Johns Hopkins
was a co-author. The papers have been published simultaneously in
Geophysical Research Letters.
The authors think that the layers formed when ice accumulated at the
poles during past ice ages on Mars. Each time the planet warmed, a
remnant of the ice caps became covered by sand, which protected the
ice from solar radiation and prevented it from dissipating into the
Scientists have long known about glacial events on Mars, which are
driven by variations in the planet's orbit and tilt.
Over periods of about
50,000 years, Mars leans toward the sun before gradually returning
to an upright position, like a wobbling spinning top. When the
planet spins upright, the equator faces the sun, allowing the polar
ice caps to grow. As the planet tilts, the ice caps retreat, perhaps
Until now, scientists thought that the ancient ice caps were lost.
The paper (Buried
Ice and Sand Caps at the North Pole of Mars - Revealing a Record of
Climate Change in the Cavi Unit with SHARAD) shows that
in fact significant ice sheet remnants have survived under the
planet's surface, trapped in alternating bands of ice and sand, like
layers on a cake.
Co-author Jack Holt, a professor at the
Lunar & Planetary Laboratory of the University
of Arizona, said that the study provides new,
important insights into the exchange of water ice between the poles
and the mid-latitudes, where his research group previously confirmed
the presence of widespread glaciers, also using the
A composite image showing alternating layers of ice and sand
in an area where they are exposed on the surface of Mars.
The photograph, taken with the HiRISE camera
aboard NASA's Mars Reconnaissance Orbiter,
was adjusted to show water ice as light-colored layers
and sand as darker layers of blue.
The tiny bright white flecks are thin patches of frost.
Credit: NASA/JPL/University of Arizona
total volume of water locked up in these buried polar deposits
is roughly the same as all the water ice known to exist in
glaciers and buried ice layers at lower latitudes on Mars, and
they are approximately the same age," he said.
Holt, who was a UTIG
scientist and research professor for 19 years before joining the
University of Arizona in 2018, has been a co-investigator with
SHARAD since the spacecraft arrived at Mars in 2006.
Nerozzi said that studying this record of past polar glaciation
could help determine whether Mars was ever habitable.
much water was available globally versus what's trapped in the
poles is important if you're going to have liquid water on
Mars," Nerozzi said.
"You can have all the
right conditions for life, but if most of the water is locked up
at the poles, then it becomes difficult to have sufficient
amounts of liquid water near the equator."