An article published in the journal “Icarus” describes a research that suggests new possibilities for the gravitational effects of trans-Neptunian celestial bodies to generate heat on other celestial bodies close enough such as in the case of Pluto and Charon. A team of researchers examined the influence of that type of heating on bodies that may have very low temperatures but that under certain conditions can host underground oceans whose duration could be lengthened.
The underground oceans of Europa and Enceladus have been studied for several years for the many perspectives that offer about the possibility of liquid water in places where it seemed impossible until a few decades ago with great consequences on the research of alien life forms. These two moons can have liquid water thanks to the heat generated by the force of gravity of two giant planets, respectively Jupiter and Saturn, but what about other planets, dwarf planets and moons far away from the Sun and giant planets?
On the surface of trans-Neptunian objects (TNOs) the temperature is below -200° Celsius (-350° Fahrenheit) so the idea that there are underground oceans of liquid water may seem unlikely. Despite this, there are processes such as radioactive decay that can generate heat in the depths of a planet or a moon heating the water enough to melt it. Considering the fact tha thte presence of water seems common in the solar system, it’s an important possibility.
This kind of theory was proposed already years ago, in particular in the case of Pluto. In November 2016, two researches tried to explain what seems to be a reorientation of the dwarf planet with the presence of an underground ocean and those were only the latest two researches that offer clues that confirm that theory.
If originally Pluto and its great moon Charon contained radioactive materials in such quantities as to generate the heat needed to create underground oceans, they would have now decayed. Perhaps those oceans froze up but what about the gravitational influence these two bodies exert on each other? Compared to those of Jupiter or Saturn it seems limited but according to this new research it could provide an important contribution in keeping already existing oceans.
In the case of some trans-Neptunian objects, traces of crystalline water ice and ammonium hydrate were found, compounds that can’t exist at the temperatures on their surface. The most likely theory is that they emerged from the underground thanks to the presence of cryovolcanoes such as Wright Mons on Pluto.
The presence of liquid water would be interesting because it’s necessary for the development of life forms as we know them but it’s only the beginning. The interest in the oceans of Europa and Enceladus is also due to the presence of hydrothermal sources where chemical reactions occur with various compounds, an environment similar to the one in which perhaps life on Earth was born. On Pluto, Charon and other trans-Neptunian objects it’s not certain that such conditions ever existed.
Our knowledge of trans-Neptunian objects has been improving over time, so these researches are constantly developing as well. For this reason, the authors of this study intend to keep on developing their models concerning the heating caused by gravitational tides.