Surprise! Pluto may have had an underground ocean from the very beginning

Pluto may be a more habitable world than scientists had thought. Though Pluto is now famously frigid, it may have started off as a hot world that formed rapidly and violently, a new study finds. This result suggests Pluto may have possessed an underground ocean since early on in its life, potentially improving its chances of hosting life, researchers said.

Previous work assumed Pluto originated from cold and icy rock clumping together in the distant Kuiper Belt, the ring of objects beyond Neptune’s orbit. Although there is evidence that Pluto currently possesses a liquid ocean beneath its thick frozen shell, researchers have suggested this subsurface ocean developed long after Pluto formed, after ice melted due to heat from radioactive elements in Pluto’s core. Now scientists argue that instead of a cold formation, Pluto had a hot start, one full of explosive force. “When we look at Pluto today, we see a very cold frozen world, with a surface temperature of about 45 Kelvin [minus 380 degrees Fahrenheit, and minus 228 degrees Celsius],” study lead author Carver Bierson, a planetary scientist at the University of California, Santa Cruz, told Space.com. “I find it amazing that by looking at the geology recorded in that surface, we can infer Pluto had a rapid and violent formation that warmed the interior enough to form a subsurface water ocean.”

The researchers analysed so-called “extensional features” on Pluto’s surface. Water expands as it freezes, so as Pluto’s interior cooled, Pluto’s surface stretched, generating recognizable structures. Extensional features the researchers saw on Pluto’s icy surface — for instance, cracks in its shell, and an enigmatic system of ridges and troughs — suggest Pluto had a hot start.

“I think the most exciting implication is that subsurface oceans may have been common among the large Kuiper Belt objects when they formed,” Bierson said. These findings suggest that Pluto and other large dwarf planets in the Kuiper Belt, such as Eris, Makemake and Haumea, may have possessed subsurface oceans ever since they formed. This may have influenced the potential habitability of these distant icy worlds, the researchers said.