A new study led by Dr. Alan Stern, planetary scientist and deputy director of the Southwest Research Institute (SwRI), shows that a large hill, about 5 kilometers long, dominates the appearance of the large lobe of the pristine Kuiper belt object Arrokoth. Suffice it to suggest a common origin, assuming similarity. The SwRI study suggests that these “building blocks” could guide further research into models of planetesimal formation. Stern presented these findings this week at the American Astronomical Society’s 55th Annual Meeting of the Division of Planetary Sciences (DPS) in San Antonio. These results have also now been published in a peer-reviewed journal. Planetary Science Journal.
NASA’s New Horizons spacecraft approached Arrokoth in 2019. From these data, Stern and his co-authors identified 12 hills on Wenu, a large salient part of Arrokoth, that had roughly the same shape, size, color, and reflectance. They also tentatively identified three more hills on the object’s small lobe, Weyo.
Dr. Will Grundy, a co-investigator on the New Horizons mission at the Lowell Observatory, said: “This object is extremely well preserved and its shape reveals details about how it was assembled from a series of components that look very similar to each other. It’s amazing what we’re seeing firsthand.” . “Allochus looks almost like a raspberry and is made up of small subunits.”
The geology of Arrokoth supports the fluid instability model of planetesimal formation. In this model, impact velocities of just a few miles per hour led to the construction of Arrokoth, with objects gently accumulating in local regions of the solar nebula where gravitational collapse was occurring.
“The similarities, including size and other properties, of Arrokoth’s mound structures suggest new insights into their formation,” said Stern, principal investigator of the New Horizons mission. “If this hill indeed represents a component of an ancient planetesimal like Arrokoth, planetesimal formation models would need to account for the preferred size of these components.”
It is likely that some of NASA’s Lucy mission’s flyby targets to Jupiter’s Trojan asteroids and ESA’s interceptor comets are other primitive planetesimals, which could be due to the accretion of planetesimals elsewhere in the ancient solar system. and may contribute to understanding whether they are different from the ancient solar system. Process New Horizons discovered in the Kuiper Belt.
“It will be important to explore the hillock-like structures on planetesimals that these missions observe to see how common this phenomenon is, providing further guidance to planetesimal formation theories.” “Sure,” Stern said.
The Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland, designs, builds and operates the New Horizons spacecraft and manages the mission for NASA’s Science Mission Directorate. San Antonio-based Southwest Research Institute will direct the mission through Principal Investigator Stern, who will lead the science team, payload operations, and science plan implementation. New Horizons is part of the New Frontiers program managed by NASA’s Marshall Space Flight Center in Huntsville, Alabama.
