Fields of sharp ice growing to almost 50 feet (15 m) tall could be scattered across the equatorial regions of Jupiter’s moon Europa, according to a new study published in the journal Nature Geoscience.
Terrestrial penitentes from the southern end of the Chajnantor plain, Chile, in 2005; the view is broadly northwards; blades can be seen perpendicular to the viewing direction. Image credit: ESO.
On Earth, the sublimation of massive ice deposits at equatorial latitudes under cold and dry conditions in the absence of any liquid melt leads to the formation of spiked and bladed textures eroded into the surface of the ice.
Known as penitentes, these sublimation-sculpted blades grow to between 3 to 16 feet (1-5 m) tall, but they are restricted to high-altitude tropical and subtropical conditions, such as in the Andes.
Europa, however, has the perfect conditions necessary for penitentes to form more uniformly — its surface is dominated by ice.
It has the thermal conditions needed for ice to sublime without melting; and there is very little variation in the angle in which the Sun shines on the surface.
In the new study, Cardiff University researcher Daniel Hobley and colleagues used observational data to calculate the sublimation rates at various points on Europa’s surface, and then used these to estimate the size and distribution of penitentes.
They concluded that the penitentes could potentially grow to around 50 feet tall with a spacing of around 25 feet (7.5 m) between each one.
It was also inferred that the penitentes would be more common around Europa’s equator.
“The unique conditions of Europa present both exciting exploratory possibilities and potentially treacherous danger,” Dr. Hobley said.
“The presence of sharp, blade-like structures towering to almost 50 feet high would make any potential landing mission to Europa extremely precarious.”
“We hope that studies like ours will help the engineers to develop innovative ways of delivering landers safely on Europa’s surface so that we can find out even more about this fascinating place, and potentially look for signs of extraterrestrial life.”
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Daniel E.J. Hobley et al. Formation of metre-scale bladed roughness on Europa’s surface by ablation of ice. Nature Geoscience, published online October 8, 2018; doi: 10.1038/s41561-018-0235-0
