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In the first published results of 2019 New Year's Day flyover of the New Horizons Space Shuttle by an object officially named 2014 MU69, but more commonly known as Ultima Thule, scientists have reported that despite its unusual shape, it has a remarkably bland surface, with no major variations in color or composition.
Nor does it have moons, dust clouds or detectable atmospheres, scientists report in the newspaper Science.
But that does not mean it's boring, says John Spencer, scientist in planetary science at the Southwest Research Institute in Boulder, Colorado, who is a co-author of the paper.
The most striking discovery comes from the strange shape of the object, which has two flattened lobes connected to each other by a narrow neck.
Spencer says that this structure means that the two lobes began as separate objects that gradually spiraled from one to the other during a merger that was more than one. fuck that one crash.
This is important because it gives us insight into the process in which small objects come together to produce the larger objects that eventually create the planets, he says.
But the relative blandness of the surface is also important not for what is there, but for what is not: craters.
Some craters exist, but compared to destinations visited by other spacecraft such as OSIRIS-REx from NASA and Hayabusa2 from Japan, Ultima Thule is almost as smooth as the proverbial bottom of the baby.
"If you look at the middle asteroid, it's covered with craters," says Spencer. "They are completely beaten."
This is because asteroids are much closer to the sun in an area where there is not only a dense concentration of objects, but where the orbits are easily lifted by the gravity of Jupiter.
"It means they meet at crazy angles," says Spencer.
As a result, they have not only suffered a lot of collisions in their lifetime, but have often been hit hard.
Most asteroids, in fact, are larger body fragments torn by ancient impacts, then dotted by countless smaller ones.
"These are not intact, untouched objects," says Spencer.
Ultima Thule, however, is located in a very remote part of the solar system known as the "Kuiper Classic Belt", a region beyond Neptune where the objects are quietly moving in well-spaced and well-ordered orbits. Like cars on the highway, they all move at the same speed in the same direction and therefore do not meet very often.
This means that the surface of Ultima Thule has hardly been disturbed since the advent of the solar system.
"We have never seen this before," says Spencer.
But that does not mean that its surface is as dull as a ball of shock. On the contrary, it is spotted, as it was composed of subunits of about five kilometers each. Eight of them were counted on the largest lobe, and it was only on parts of it that New Horizons could see when it passed quickly.
"You have the idea that it's built from different pieces," suggests Spencer.
One of his colleagues, he added, described as having the appearance of a monkey bread, a pastry-shaped snack in which dumplings are cooked together in a pan and fused into one piece.
Ultima Thule was obviously not cooked in a cosmic bread pan. The question of how its components integrate so well is therefore an open question. At first they may have been soft and supple, and somehow stuck to each other, Spencer thought.
But for now, he concedes: "We gratify our heads."
As for the other results, the absence of any atmosphere or detectable amounts of gas coming out of the surface of Ultima Thule was not a surprise.
The object is far from the sun and has been in the same orbit for four and a half billion years. If there had been degassed gas, it would probably have been done a long time ago.
But it would have been silly to spoil a unique opportunity to find surprises.
"We searched for things even though we did not expect to see them," he says.
On the other hand, the lack of moons was a disappointment, as their orbits would have allowed scientists to calculate the mass of Ultima Thule and, hence, its density, a useful index of its inner composition.
It's not that scientists are certain that there are no moons.
"We are always looking," says Spencer. The spacecraft, he adds, continues to download data, although most of the high-priority scientific data has already been received.
The next series of scientific analyzes will probably be published in August or September.
After that, the scientists will focus their attention on finding a new destination for New Horizons, for another flyby, accessible with the remaining fuel from the probe.
Finding such a destination will be difficult, however, because there are not so many objects so far away, and those that exist are so dark that they are hard to find.
"I think it's a long shot," says Spencer, "but we certainly do not mind, we'll do our best."
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