An article published in the magazine “Icarus” describes a research that offers an explanation for the origin ice blades that are tens of meters high found on Pluto. According to a team of researchers led by Jeffrey Moore, one of NASA’s New Horizons mission scientists, those blades originated in the freezing and subsequent erosion of methane at the highest altitudes of the dwarf planet, with a process similar to what happens on the Earth, for example on the Andes, but with much larger sizes.
Among the many discoveries made by NASA’s New Horizons space probe in its Pluto flyby culminated on July 14, 2015, there are ice ridges similar to those existing on Earth and called penitents or snow penitents. The ones on Pluto are much bigger, reaching 500 meters of hight against the few meters of those on the Earth’s Andes.
Ice blades are present in areas where solar irradiation is minimal. There, deposits of methane form but the conditions determine those strange shapes. The key is in the climatic variations that occur on Pluto, where even a small change in solar irradiation can make a big difference. A slight temperature rise is enough for methane ice to start sublimating, turning into gas eroding the deposits until they they get shaped the way discovered by the New Horizons space probe.
That erosion suggests that the climate on Pluto changed over millions of years, ending up createing the huge ice blades. The fact that this happened to methane ice deposits prompted the researchers to map their presence on the dwarf planet to try to figure out which areas are at highest altitudes.
The areas photographed on July 14, 2015 can be best studied with high resolution images but it’s just a hemisphere. Other areas were photographed only before and after the New Horizons space probe’s closest approach, which means that the image quality is lower.
The bottom image shows maps based on topographic data (the top one) and on the composition (lower) of Pluto’s surface. In the area covered by high resolution images, the circled region has a high altitude. The same region is indicated for the presence of methane but that compound is present in other regions, indicated in orange.
Ice blades may be present in many Pluto regions but the resolution of the available images may not be enough to locate them and there’s a part of the surface that wasn’t photographed. The researchers are working to better understand the dwarf planet’s geology, which is providing interesting information about its history.
