On Earth, solar radiation can transmit down to multiple meters within ice, depending on its optical properties. Organisms within ice can harness energy from photosynthetically active radiation while being protected from damaging ultraviolet radiation. On Mars, the lack of an effective ozone shield allows approximately 30% more damaging ultraviolet radiation to reach the surface in comparison with Earth. However, new research shows that despite the intense surface ultraviolet radiation, there are radiatively habitable zones within ice in the Martian mid-latitudes, at depths ranging from a few centimeters for ice with 0.01-0.1% dust, and up to a few meters within cleaner ice.
“If we’re trying to find life anywhere in the Universe today, Martian ice exposures are probably one of the most accessible places we should be looking,” said Dr. Aditya Khuller, a researcher at NASA’s Jet Propulsion Laboratory.
Mars has two kinds of ice: frozen water and frozen carbon dioxide.
Dr. Khuller and colleagues looked at water ice, large amounts of which formed from snow mixed with dust that fell on the surface during a series of Martian ice ages in the past million years.
That ancient snow has since solidified into ice, still peppered with specks of dust.
Although dust particles may obscure light in deeper layers of the ice, they are key to explaining how subsurface pools of water could form within ice when exposed to the Sun.
Dark dust absorbs more sunlight than the surrounding ice, potentially causing the ice to warm up and melt up to a few feet below the surface.
Mars scientists are divided about whether ice can actually melt when exposed to the Martian surface.
That’s due to the planet’s thin, dry atmosphere, where water ice is believed to sublimate — turn directly into gas — the way dry ice does on Earth.
But the atmospheric effects that make melting difficult on the Martian surface wouldn’t apply below the surface of a dusty snowpack or glacier.
On…
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