Giant icebergs jut out of one network of fissures. It seems as though hot water had at some point exploded to the top through crevasses and immediately frozen at the surface. An ocean, in which life is perhaps possible. Here, too, there were traces of strange geological processes - but these are more pertinent to the solar system's prehistory. Then, ten years after its visit to Jupiter, Voyager 2 reached Triton, Neptune's largest moon.
Triton is the coldest object ever examined by geologists in the solar system.
It is so cold that even its thin atmosphere of nitrogen and gaseous methane freezes into a solid icecap in winter. But as Voyager approached Triton, the probe discovered strange dark stripes all over the fresh ice cover. These dark traces were clearly on the ice and were of recent origin. So some sort of active process had to be taking place. Larry Soderblom pondered the Voyager images for two months before finally finding an explanation.