Under the icy "heart" of Pluto, most likely, a huge ocean

Recently, astronomers have presented the best at thismoment of evidence of the existence of the ocean in an unexpected place - on the dwarf planet Pluto, in the dark depths of the solar system. Where nitrogen and other volatile gases freeze and water turns into ice-hard rock. For decades, scientists have been wondering whether this ice can act as a “heater” and keep the remnants of heat and moisture deep inside Pluto and other objects, so far from the Sun. However, all this time they did not have data that could confirm these surprising assumptions.

Everything changed when last year past Plutoflew the mission of NASA "New Horizons". Among the many wonders of the dwarf planet, the brightest and most striking feature that the probe saw was a plain heart-shaped 1600 kilometers wide, stretching across the surface of a distant world. The heart was called the “Tombo Region” in honor of the discoverer of Pluto, the American astronomer Clyde Tombo. Cracks and faults in the Tombo region and other parts of the planet have suggested that the surface layer of watery porridge slowly freezes through, breaking the surface during expansion. However, these cracks could explain other, drier surfaces. On Wednesday in Nature, two studies emerged that strengthened the belief of scientists that Pluto’s icy heart hides a warm and humid inner world.

"If we are right, the oceans in the outer solarthe system is quite common, and other objects of similar size to Pluto can also have subsurface oceans, ”says Francis Nimmo, lead author of the study, a planetologist at the University of California, Santa Cruz.

New evidence in favor of the ocean on Plutocame from the western part of the Tombo region, 1000 kilometers wide, informally called Sputnik Planitia. "Satellite Plan" is rather strange when compared to the rest of the solid, dotted with craters, the old surface of Pluto, because it is covered with bright, relatively fresh ice and has no craters. Scientists explained the young Sputnik Planitia look to the fact that it is an ancient shock basin - a giant crater filled with thick ice floes of young ice, which, under the influence of heat leaking from below, melts and refreshes the surface. The most curious thing about Sputnik Planitia is its location: along the equator in a curious alignment with respect to the largest moon of Pluto, Charon. Charon is tidal blocked with Pluto, its orbit is synchronized with the rotation of Pluto, so it seems to hang in immobility over the region directly opposite to Sputnik Planitia.

"If you draw a line from the center of Charon through the centerPluto to the far side of the planet, it will come out very close to Sputnik Planitia, ”says James Tuttle Kean, a doctoral student at the University of Arizona at Tucson and lead author of another Nature study. The likelihood that a giant blow will produce a crater so exactly aligned with Charon is quite small, Keen says, so he decided to look for another explanation. His team used data from the New Horizons and ground-based telescopes to create models of how the formation of Sputnik Planitia could affect the subsoil and orbital evolution of Pluto.

Both teams found that strange alignmentwith Charon, the easiest way to explain this is that Sputnik Planitia is much more massive than the surrounding regions on Pluto. For millions of years, this "anomaly of the positive mass" led to the fact that the entire planet bent and fell into the present position. Modeling the process, the Keen team found that if Sputnik Planitia had formed to the north-west of its present position, the consequences of its reorientation through the equator would lead to cracks, canyons and mountains, which practically correspond to those observed by the “New Horizons”.

Team Nimmo believes that the subsurface ocean- the most likely reason that Sputnik Planitia is heavier than its surroundings. The birth of this region during a giant collision was supposed to lift so much ice from the surface of Pluto that watery slush rose and thickened, forming such a bruise on the surface of the planet. Nimmo's models say that Pluto’s ocean is 100 kilometers deep and it is billions of years old, it has a lot of liquid ammonia, natural antifreeze, which is present in many ice bodies of the external solar system. Although the ocean of Pluto could, in principle, support life, it is locked under a 200-kilometer layer of ice and very far from Earth, so it is unlikely to explore it - it is easier to search for life in other subsurface oceans of the Solar System.