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Home / Science / The latest image from Ultima Thule shows a remarkably smooth face

The latest image from Ultima Thule shows a remarkably smooth face



Ultima Thule has a new wanted shot.

The closest image of the old Kuiper Belt object flown by the New Horizons plane on January 1 shows a relatively smooth face that is not touched by impact craters.

"The thing just is not covered in craters," says planetary scientist Kelsi Singer of the Southwest Research Institute of Boulder, Colorado, released on January 24th.

This lack of strike colors suggests that the Kuiper Belt, a reservoir of ancient space rock beyond Neptune's orbit, has fewer small objects than scientists expect. If so, it could mean that the precursors of the planets grew up quickly without leaving behind many protoplanetary crumbs.

Snapshots when New Horizons flied past Pluto and its moons in 201

5 showed that these bodies are surprisingly smooth too. Many Pluto's craters may have been covered by geological activity on the dwarf planet, such as Eg the movement of glaciers ( SN Online: 15.10.15 ). But Pluto's largest moon Charon is considered less active and should therefore not erase its craters ( SN Online: 13/7/18 ). Singer and her colleagues have argued that the lack of craters meant that there were not so many small objects found in Pluto and Charon.

"Unless you can get the geology to erase the craters on Charon, that's especially nice to an inescapable conclusion that you do not even have to make the craters," says Singer.

The real test of this The idea came with the passing of New Horizons by Ultima Thule, whose official name is MU69, and that if MU69 did not lack small craters that would result in relatively few small objects in the outer solar system with which it could collide, argue Singer and Colleagues in a newspaper published in arXiv.org in December.

The latest image from MU69 shows only a few small craters at the top – where shadows emphasize crater rocks – probably from objects that are about 100 meters wide Deepening of the smaller of the two lobes of the object could be an impact crater left by an approximately 700 meter wide object

A lack of small objects that could imprint bodies like MU69 could preclude some theories about the planets and their planets. An idea at the time in the early solar system is that dust grains were slowly put together to gradually form larger bodies. Another theory is that larger objects collided and smashed themselves to pieces. But both scenarios today would probably have many small objects hovering in the Kuiper belt, says Singer.

If protoplanets solidified directly from the gas and dust mist that preceded the formation of the solar system, they would have been able to extend to tens to hundreds of kilometers relatively quickly, says Singer. That means that there would be few little cosmic kibbles and bits.

Planet scientist Alessandro Morbidelli from the Côte d & # 39; Azur Observatory in Nice, France, says it's premature to draw any conclusions. Krater counts on Pluto and Charon are not reliable, he says. And although he agrees that MU69 is the "ultimate test," he says that higher-resolution images are needed to see if the barely distorted face can stand a closer scrutiny. The current best picture was taken seven minutes before New Horizons & # 39; s closest approach to MU69, when the spacecraft was still 6,700 kilometers away. Better pictures are on the spacecraft computer, waiting to be transmitted to Earth.

New Horizons will continue to send data to MU69 by September 2020.


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