PLUTO could hide a liquid ocean beneath its icy shell. Indeed, other bodies on the solar system's frigid fringe could also harbour subsurface oceans, and these could provide the conditions to sustain life.
Temperatures on Pluto's surface hover around -230 °C, but researchers have long wondered whether the dwarf planet might boast enough internal heat to sustain a liquid ocean under its icy exterior.
Now Guillaume Robuchon and Francis Nimmo at the University of California, Santa Cruz, say there is a good chance it does. They calculate that an ocean depends on two things: the amount of radioactive potassium in Pluto's rocky core, and the sloshiness of the ice that covers it.
Density measurements suggest a rocky core fills 40 per cent of the dwarf planet's volume. If the core contains potassium at a concentration of 75 parts per billion, its decay could produce enough heat to melt some of the overlying ice, which is made of a mixture of nitrogen and water.
It should have at least that much potassium and probably more, says William McKinnon at Washington University in St Louis, Missouri. He points out that Earth, which probably formed with less of the volatile element due to its closer distance to the sun, has 10 times that concentration in its core.
But merely having a source of heat is not enough to maintain a long-lived ocean. Heat from the core will trigger convection in the surrounding ice, and if the ice churns too quickly, the heat will simply escape into space before it can do much melting. If it flows substantially more slowly than Antarctic glaciers on Earth, however, then the top 165 kilometres of ice could provide enough insulation for a liquid ocean of the same depth to exist below, the team calculates
Would that be something a fake planet wouldn't do, Dr. Neil DeGrasse Tyson? Is it? Hmph!
[Source: New Scientist]