Recently discovered layers of ice buried one mile below Mars' north pole are remnants of ancient polar ice sheets and may be one of the largest water reservoirs on the planet, according to researchers at the University of Texas at Austin and the University of Arizona.
The team made the discovery using measurements collected by the small radar (SHARAD) on NASA's Mars Reconnaissance Orbiter (MRO). SHARAD emits radar waves that can penetrate up to one and a half miles below Mars.
The results, published on May 22 in Geophysical Research Letters are important because the ice layers are a record of past climates on Mars in much the same way as tree rings are a record of past climate on Earth. To study the geometry and composition of these layers can tell the researchers whether the climatic conditions were previously favorable for life, said researchers. The team found layers of sand and ice that were as much as 90% water in some places.
If it was melted, the newly discovered polar ice would correspond to a global water layer around Mars at least 1
"We didn't expect to find this much water ice here," says senior author Stefano Nerozzi, research assistant at the University of Texas Institute for Geophysics (UTIG), who ends his Ph.D. at the Jackson School of Geosciences. "It probably makes it the third largest water tank on Mars after polar ice caps."
The results were confirmed by an independent study of gravity data instead of radar, led by researchers at Johns Hopkins University. Nerozzi was co-author. The papers have been published simultaneously in Geophysical Research Letters .
The authors believe that the layers were formed when the ice accumulated at the poles during the earlier ice age on Mars. Each time the planet was warmed, a remnant of the iceberg was covered with sand, which protected the ice from solar radiation and prevented it from spreading into the atmosphere.
Scientists have long known about ice events on Mars driven by variations in the planet's orbit and slope. For 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, the equator establishes the sun so that the polarizers can grow. As the planet slides, the ice will return, perhaps disappearing altogether.
So far, scientists have believed that the old captains were lost. The paper shows that actual significant ice sheet residues have survived under the surface of the planet, trapped in alternating bands of ice and sand, which layer on a cake.
Co-author Jack Holt, a professor at the Lunar & Planetary Laboratory of the University of Arizona, said the study provides new important insights into the exchange of water ice between the poles and the centerline, where his research group previously confirmed the presence of widespread glaciers, even with the help of SHARAD –the.
"Surprisingly, the total volume of water locked in these buried polar deposits is about the same as any water known to exist in glaciers and buried ice layers at lower latitudes on Mars, and they are about the same year," 19659003] Holt, a UTIG researcher and research professor for 19 years before joining Arizona in 2018, has been a co-researcher with SHARAD since the spacecraft arrived in March 2006.
Nerozzi said it was important to study this record of past polar glaciation, if Mars was ever habitable. "Understanding how much water is available globally compared to what is caught in the poles is important if you are to have floating water on Mars," said Nerozzi. can have all the right conditions for life, but if most of the water is blocked in the poles, it will be difficult to get enough liquid water near the equator. "
The study was supported by a contribution from the NASA Mars Data Analysis Program and the MRO Project Office at Jet Propulsion Laboratory. SHARAD was provided to NASA's MRO mission by the Italian Space Agency.