American Geophysical Union | 2019 May 22
Scientists have discovered remnants of ancient ice sheets buried in sand a mile beneath Mars’s north pole, they report in a new study. The findings show conclusive evidence of the waxing and waning of polar ice on the red planet due to changes in its orbit and tilt, according to the study’s authors.
Researchers at the University of Texas at Austin and the University of Arizona made the discovery using measurements gathered by the Shallow Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter (MRO). SHARAD emits radar waves that can penetrate up to a mile and a half beneath Mars’s surface.
The new findings ... 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, according to the researchers. Studying the geometry and composition of these layers could tell scientists whether climate conditions were previously favorable for life.
The team found layers of sand and ice that were as much as 90 percent water in some places. If melted, the newly discovered ice would be equivalent to a global layer of water around Mars at least 1.5 meters (5 feet) deep, which could be one of the largest water reservoirs on the planet, according to the researchers. ...
Buried Ice and Sand Caps at the North Pole of Mars: Revealing a Record
of Climate Change in the Cavi Unit with SHARAD ~ Stefano Nerozzi, Jack W. Holt