hen NASA's New Horizons spacecraft flew past Pluto in 2015, researchers hoped that its data would help them unravel some of the dwarf planet's mysteries. Instead, the discoveries made during the close-up look at Pluto and its moon Charon revealed more questions that needed answering. One of the big revelations from the flyby was the discovery of an ocean beneath the icy shell encapsulating Pluto. The ice shell was thin in a spot near the equator that's about the size of Texas, known as Sputnik Planitia, which helped researchers notice Pluto's odd topography and suggest the ocean's existence. But this...