Data gathered by the New Horizons spacecraft have revealed there are fewer very small objects in the Kuiper Belt than previously believed.

Craters On Pluto And Charon

Study researcher Kelsi Singer of the Southwest Research Institute (SwRI) in Boulder, Colorado, and colleagues studied the photos captured by New Horizons during its flyby of Pluto in July 2015.

They counted and characterized the craters on the dwarf planet and its largest satellite Charon. Imaging of the Vulcan Planum, a large plain on the surface of Charon, showed impact features that are highly visible and appeared to be well-preserved over long time spans.

There are few craters less than 8 miles wide, which means a distinct scarcity of Kuiper Belt objects or KBOs between 0.6-mile and 1.2-mile in size.

Since crater size is tied to the size of the impacts, the researchers were able to map out the size-frequency distribution of small objects in the Kuiper belt that is too faint to be captured by space and ground telescopes.

"New Horizons flying directly through the Kuiper Belt and collecting data there was key to learning about both large and small bodies of the Belt," Singer said.

The images of a distinct dearth of small craters on Pluto and its largest moon suggest collisions with small KBOs are rare and there are fewer small objects zooming through the Kuiper Belt than previously thought.

Kuiper Belt

The Kuiper belt is a donut-shaped region consists of icy bodies beyond Neptune. Small KBOs are among the feedstock from which planets form, so the findings offer new insights into the origin of the solar system.

"Some surfaces on Pluto and Charon are likely ≳4 billion years old, thus their crater records provide information on the size-frequency distribution of KBOs in the early Solar System," Singer and colleagues wrote.

The findings were published in the journal Science on March 1.

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