A group of scientists presents a new possibility of what celestial body could Pluto really be as its demotion as a dwarf planet continues to stir debate.
The scientists from the Southwest Research Institute toyed with the idea that Pluto could actually be a giant comet after all. To test this premise, the scientists created a cosmochemical model of Pluto
Dr. Christopher Glein of SwRI's Space Science and Engineering division and his team developed what they called "the giant comet cosmochemical model of Pluto formation."
Through the model, the team arrived at a conclusion that a previously discovered glacier on Pluto's surface, the Sputnik Planitia, has the similar nitrogen composition to that of the comet 67P/Churyumov-Gerasimenko.
"We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta," Glein explained.
This large glacier, comprised of ice that is rich in nitrogen, was formed at the left lobe of the bright Tombaugh Regio feature on Pluto's surface. It was first discovered by NASA's New Horizon in 2015 and estimated to be 100 million years old. It was still being shaped by a geologic process at the time of discovery.
The glacier has shallow trenches that contained darker material than the glacier's even surfaces. Some of these trenches also appeared like clumps of hills protruding from the surrounding terrain.
The Sputnik Planitia also has some portions that appeared to have formed by a process called sublimation where ice turns directly from solid to gas.
The glacier's irregular shape may have resulted from the contraction of surface materials like what happened when mud on Earth dries. The irregular shape may also be a result of convection process brought by frozen carbon monoxide, methane and nitrogen, and the temperature of Pluto's interior according to NASA.
This comet was the target landing of ESA's Rosetta mission. Hence, the Comet 67P/Churyumov-Gerasimenko made history when it became the first comet to be orbited and landed by robots from Earth in August 2014.
One significant finding from the Rosetta mission was that some of the comet's dust grains contained a suite of 16 organic compounds comprising numerous carbon and nitrogen-rich compounds.
The comet's nucleus was found to be less dense than water and emit twice as much dust gas when heated by the Sun.
The Probability That Pluto Is A Giant Comet
Glein and his team's next step would be to examine the nitrogen present in Pluto and how much of the volatile element potentially could have leaked out of its atmosphere.
"A volatile is defined here as a chemical species that can readily transition in a macroscopic sense between gaseous and condensed forms at the temperature of a planetary body," the team wrote in its paper titled Primordial N2 provides a cosmochemical explanation for the existence of Pluto's Sputnik Planitia.
For the meantime, "the giant comet cosmochemical model" created by the team suggested that Pluto has a chemical composition inherited from cometary building blocks. This initial composition may have been modified by liquid water coming from the possible subsurface ocean.