Pits and channels on Mars' icecap, and a giant cryovolcano on Pluto
NASA Mars Reconnaissance Orbiter image of the seasonal cap of carbon dioxide ice on Mars. Open the image in a new tab or window and then click on it for a super closeup view. (Source: NASA)
The highest-resolution color view yet of one of two possible ice volcanoes spotted on the surface of Pluto by the New Horizons spacecraft in July 2015. Open this image too in a new tab or window so you can zoom in for an extreme closeup view. (Source: NASA/JHUAPL/SwRI) When I first saw the landscapes in these two images, I was struck more by their similarities than their differences. But of course looks can be deceiving. And while both landscapes do involve ice, each turns out to be very different. At the same time, they are also compelling examples of the amazing diversity of natural processes found on the different worlds of our solar system. With all of this in mind, I thought I'd put the images together in one post for readers of ImaGeo to enjoy. On the Martian icecap (the top image), gas flowing beneath the planet's seasonal carbon dioxide icecap blows out into the atmosphere, creating pits. (NASA calls them "troughs," but they don't look that way to me.) The escaping gas carries dust from the Martian surface beneath the ice. As it falls back down, it creates dark, vaguely reddish, fan-shaped deposits visible in the image, acquired by NASA's Mars Reconnaissance Orbiter. And radiating from the pits are lovely dendritic erosion channels. Covering an area about 1 kilometer, or 0.6 miles across, this is actually a remarkably close up image of Mars. By my rough estimate, the largest of the dark pits is about the size of a football field. And that means those channels are no wider than a street. (Again, roughly speaking.) By contrast, the image of Pluto is 140 miles, or 230 kilometers, across. And the possible ice volcano it reveals — that pit-like feature with reddish stuff at its mouth — is gigantic: 90 miles (150 kilometers) across and 2.5 miles (4 kilometers) high. "If it is in fact a volcano, as suspected, it would be the largest such feature discovered in the outer solar system," according to a NASA release that featured the image, which was acquired by the New Horizons spacecraft as it zipped past Pluto in July of 2015.
Plutonian landscapes. (Source: NASA/JHUAPL/SwRI) A fair portion of Pluto is covered in reddish material, as is evident in the image above. The reddish stuff is also seen scattered about in the landscape around the possible ice volcano, dubbed Wright Mons by the New Horizons team in honor of the Wright brothers. But as the inset show, it's much sparser. And mission scientists are not sure why. This stuff consists of tholins, organic brown gunk (aka "star tar") that rains out of Pluto's atmosphere.
I'm not sure that I can quite make it out, but NASA says one impact crater is visible on Wright Mons. This suggests the surface visible here is relatively young, and that Wright Mons has been volcanically active in the not so distant past.