In the kingdom of Pluto, small objects are rare


A new study suggests that the distant kingdom of Pluto is a haven for primitive and primitive relics of the early solar system.

Researchers have noted a marked shortage of small craters on Pluto and its largest moon, Charon, indicating that fewer and fewer dwarf corps are bombarding the Kuiper Belt – The ring of icy bodies beyond Neptune – as previously thought.

This information, in turn, implies that collisions are a rare solution and that most objects in the Kuiper Belt (KBO) have avoided significant disruption over the centuries, team members said. # 39; study.

Related: Destination Pluto: NASA's new mission: Horizons in pictures

The researchers – led by Kelsi Singer of the Southwest Research Institute (SwRI) of Boulder, Colorado – have been studying photos captured by NASA's New Horizons satellite during his epic. July 2015 Overview of Pluto.

They counted and characterized the craters on the dwarf planet and Charon, focusing particularly on an ancient and smooth plain of Charon known as Vulcan Planitia. There, the impact characteristics are very visible and seemingly well preserved over long periods.

Of course, the size of the crater being related to the size of the impactor, the team was able to map a frequency-size distribution for small KBOs – bodies too weak to be seen by telescopes here on Earth or in Earth orbit .

"It's impossible to get this information without sending a probe to the external solar system," said Singer, a member of New Horizons' science team, at

She and her colleagues found surprisingly few craters less than 13 km wide, which suggests a pronounced rarity of KBO of the order of 1 km to 2 km.

Such scarcity is also implicated by the scarcity of small impact features on Ultima Thule, the 34-kilometer wide object that New Horizons flew over on Jan. 1. This second overview of the craft, the planetary encounter furthest from the history of spaceflight, is the centerpiece of New Horizons' expanded mission, which expands until 2021.

These twin results are at odds with the models based on the situation of the internal solar system. Small bodies are relatively common in the grove of the Earth. Astronomers see some of these pipsqueaks in the main asteroid belt between Mars and Jupiter, while the Moon retains many craters ejected by small impactors.

But it is becoming more and more obvious that the Kuiper belt is very different from the asteroid belt, Singer said. So do not be too surprised if the population of the Kuiper belt is not in "collision equilibrium" because the objects of the asteroid belt seem to be and are dominated by celestial time capsules that scientists can explore to learn about the beginnings of the solar system.

Nevertheless, Singer – and many other researchers – would like to take a closer look at another KBO to help us sharpen our nascent understanding of this dark and mysterious region.

"Seeing other surfaces in the Kuiper Belt would be great," said Singer.

New Horizons could actually do it. The spacecraft is healthy and has enough fuel to perform a flying over a third object if NASA grants another mission extension, said the team members.

The new document was published online today (February 1st) in the newspaper Science.

Mike Wall's book on the search for extraterrestrial life, "Over there"(Grand Central Publishing, 2018, illustrated by Karl Tate), is out now. Follow him on Twitter @michaeldwall. Follow us on twitter @Spacedotcom and sure Facebook.

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