Pluto and other distant worlds may have buried the oceans – tech2.org

Pluto and other distant worlds may have buried the oceans



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  Pluto and other distant worlds may have buried oceans

This composite and enhanced image of Pluto (bottom right) and its largest moon, Charon (top left), was taken by the New Horizons spacecraft from NASA on July 14. 2015. Pluto and Charon are shown with roughly correct relative sizes, but their true separation is not to scale.

Credit: NASA / JHUAPL / SwRI

Our solar system can host many more potentially habitable worlds than scientists had thought.

The subsurface oceans could still slide beneath the icy shores of cold, far-away worlds like the dwarf planets Pluto and Eris, held in liquid state by the pull of the moons in heat-generating orbit, according to a new study.

"These objects should be considered as potential reservoirs of water and life," lead author Prabal Saxena of NASA's Goddard Space Flight Center in Greenbelt, Maryland, said in a statement. "If our study is correct, we can now have more places in our solar system that possess some of the critical elements for extraterrestrial life." [6 Most Likely Places for Alien Life in the Solar System]

Underground oceans are known or suspected to exist in a series of icy worlds, including the Saturn Titan and Encelad satellites and the Jovian moons Europa, Callisto and Ganymede. These oceans remain liquid until today thanks to the "warming of the tides": the powerful gravitational attraction of the giant planetary fathers of these worlds extends and flexes their interiors, generating heat through friction.

The new study suggests that something similar may be happening with Pluto, Eris and other transneptunian objects (TNO).

It is believed that many of the moons around the TNOs were joined from the material thrown into space when the objects crashed against their parents bodies long ago. That is the history of origin perceived for the only known satellite of Eris (called Dysnomia) and for the five moons of Pluto (as well as for the moon of the Earth).

Such impact-generated moons generally begin their lives in relatively chaotic orbits, team members in the new study said. But over time, these moons migrate to more stable orbits, and when this happens, satellites and TNOs pull each other gravitationally, producing tidal heat.

Saxena and her colleagues modeled the extent to which this warming could warm the interiors of TNOs – and the researchers obtained some intriguing results.

  A composite photo of Wright Mons, one of two possible cryo-volcanoes discovered on the surface of Pluto by New Horizons in July 2015.

A composite photo of Wright Mons, one of two possible cryo-volcanoes discovered on the surface of Pluto by New Horizons in July 2015.

Credit: NASA / JHUAPL / SwRI

"We found that tidal warming can be a turning point that may have preserved the oceans of liquid water beneath the surface of big TNOs like Pluto and Eris to this day, "said study co-author Wade Henning, of NASA Goddard and the University of Maryland, in the same statement.

As the term "inflection point" implies, there is another r factor at play here as well. It has been widely recognized that TNOs could harbor buried oceans thanks to the heat produced by the decomposition of the radioactive elements of the objects. But the time that those oceans could persist has not been clear. This type of heating is eventually exhausted, as more and more radioactive material is decomposed into stable elements. And the smaller the object, the faster it cools.

Warming the tides can do more than lengthen the lives of the subsurface oceans.

"Fundamentally, our study also suggests that tidal warming could make buried oceans more accessible for future observations by moving them closer to the surface," said study co-author Joe Renaud of George Mason University in Virginia. "If you have a layer of liquid water, the additional heat from the heating of the tides would cause the next adjacent layer of ice to melt."

The new study was published online last week in the Icarus magazine.

Follow Mike Wall on Twitter @michaeldwall and Google+. Follow us @Spacedotcom Facebook or Google+. Originally published on Space.com.

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