When NASA new horizons The mission passed by Pluto in 2015, giving humanity the first glimpse of the world's isolated giant depression. Its name is “Sputnik Planum”. Sputnik Planitia, which is comparable in size to Mexico and dominates one of Pluto's hemispheres, is likely the result of an impact, but Sputnik Planitia's distinctive pear-shaped impact crater is rare.
How Sputnik Planitia formed remains unclear, but researchers are now painting a complete picture of its possible origins. They say an object the size of Switzerland may have collided with Pluto at a shallow angle in the distant past. If true, this photo could hint at what Pluto's interior looks like beneath its ultra-cold surface.
Related: Why isn't Pluto a planet?
“Most people thought that Sputnik Planitia originated from an impact, but no one could explain its distinctive pear shape,” said Harry Ballantyne, an astronomer at the University of Bern in Switzerland. told Dotcom.
Sputnik Planitia's shape and sheer size (about 2,000 kilometers (1,243 miles) long and 1,600 kilometers (994 miles) wide) aren't the only reasons planetary scientists are observing it with curiosity. . Whatever formed this formation was able to carve out a depression 4 kilometers (2.5 miles) deep. At the bottom of the fissure, nitrogen ice appears to be frozen and spreading. Gravity would have caused Pluto to slowly rotate, and the dent and its lost mass would have ended up at one of Pluto's poles, but strangely Sputnik Planum remains near the equator.
One of the popular theories was suggested Sputnik Planitia was actually a hint of a global ocean buried beneath Pluto's surface. After a massive impact, liquid water may have risen from the ocean to fill the gap and then be covered in ice with a nitrogen coating, which explains why Sputnik Planum remained on the equator. Still, some scientists remain unconvinced.
“I never accepted the idea that Sputnik would need a global ocean to reach the equator.” Eric Asfagastronomers at the University of Arizona told Space.com. “In my opinion, it's much easier to explain if you start and end with a solid body that can withstand this kind of impact.”
Therefore, Asfaug, Ballantine, and colleagues set out to conduct a three-dimensional simulation to understand the conditions under which Sputnik Planitia occurred. The feature's odd shape suggested that the dent's creator struck Pluto obliquely rather than head-on. So they ended up simulating a 700-kilometer-wide (435-mile-wide) object (a ball of ice and rock) colliding with a Pluto-like world. This object was also constructed with a rock-like core inside a shell of water ice, and the impact was delivered at a shallow 30-degree angle. In fact, the team found that this scenario not only resulted in a pear-shaped crater, but that the impactor's core remained buried beneath Sputnik Planum, giving it the extra mass it needed to stay on the equator. It was shown in the simulation.
The authors say future research will be needed to extend these concepts to understand how Sputnik Planum evolved over billions of years and how collisions occur in the far corners of the solar system. states that it is still necessary.
“There's still a lot to learn about planetary collisions.” Adeen DentonA planetary scientist at the University of Arizona and one of the study's authors told Space.com. “And especially in the Kuiper Belt, there's a lot of uncertainty about what happens when ice and rock collide.”
Pluto's interior may finally help us understand those dynamics, but we may have to wait for another mission to get clearer answers. New Horizons' visit to Pluto was an amazing feat, but the spacecraft just passed by, and the mission literally just scratched the surface of its native planet. Future missions could orbit Pluto and explore its interior, including measuring the world's gravitational field.
“We need geophysical data collected around the Moon and Mars that allows us to determine in detail the internal structure of these objects,” Denton told Space.com. “There's a lot of information to be learned about Pluto's interior, and the best way to do that is by orbiting Pluto.”
The researchers published their research in a journal natural astronomy April 15th.
