An artist's concept of the New Horizons spacecraft as it visits Pluto in 2015.
Instruments will map Pluto and its moon, Charon, providing detail not only on the surface of the dwarf planet, but also about its shape, which could reveal whether or not an ocean lies beneath the ice.
Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.
When NASA's New Horizons cruises by Pluto in 2015, the images it captures could help astronomers determine if an ocean is hiding under the frigid surface, opening the door to new possibilities for liquid water to exist on other bodies in the solar system.
New research has not only concluded such an ocean is likely, but also has highlighted features the spacecraft could identify that could help confirm an ocean's existence.
Pluto's outer surface is composed of a thin shell of nitrogen ice, covering a shell of water ice.
Planetary scientists Guillaume Robuchon and Francis Nimmo, both of the University of California at Santa Cruz, wanted to find out whether or not an ocean could exist underneath this icy shell, and what visible signs such an ocean might produce on the surface.
The pair modeled the thermal evolution of the dwarf planet and studied the behavior of the shell to see how the surface would be affected by the presence of an ocean below.
Searching the surface
Ironically, the easiest feature to identify would appear if no ocean existed. As spherical bodies spin, their angular momentum tends to push material towards the equator, forming a bulge.
If Pluto boasts a liquid layer, the ice would flow, reducing such a protrusion. Thus, the appearance of a "frozen-in"primordial bulge, left over from when Pluto spun more rapidly, would signify a lack of ocean.
"If the bulge is present, it will be about 6 miles (10 km) high, so it should be readily detectable," Nimmo said. New Horizons project scientist Hal Weaver agreed on the last point.
"New Horizon imaging will measure the shape of Pluto very accurately."
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