An international team of scientists studied images of the surface of the asteroid Ryugu, taken by the Japanese probe Hayabusa-2, and found that this celestial body faced a period of strong solar heating.
Almost a year and a half ago, on February 21, 2019, the Japan Aerospace Exploration Agency (JAXA) delivered an automatic interplanetary probe Hayabusa-2 to the surface of the 900-meter near-Earth asteroid (162173) Ryugu to collect samples, and then after a shot at this celestial body with a rod from tantalum - returned the device to Ryugu orbit.
A couple of months later, the station dropped a bomb on the asteroid, took, as expected, samples of the primary matter of the solar system, and soon after that the return journey of Hayabusa-2 to Earth began: the return home is scheduled for the end of 2020.
In a new study published in the journal Science, scientists presented an analysis of high-quality images taken by the probe during its encounter with the asteroid. And the scientists' work sheds light on some of Ryugu's mysteries.
We already know that Ryugu consists of several layers and is heterogeneous: for example, rocks of red and blue colors prevail on its surface. Reddish hues are observed around mid-latitude regions, while blue hues are observed near the equator and poles, as well as impact craters. However, what this “colorfulness” is connected with is still not clear.
With detailed close-ups and videos captured by the probe during the sampling process, an international team of astronomers examined the colors and morphology of Ryugu's surface on a small scale. As a result, they concluded that the asteroid collided with a period of intense solar heating caused by changes in its orbit.
“Rocks of red color on the asteroid Ryugu could appear due to the fact that about 300 thousand years ago, its orbit temporarily changed, as a result of which the asteroid approached the Sun. Its surface began to warm up more strongly, which is why the deposits of organic matter on its surface turned red,”the scientists write.
The researchers noticed some peculiarities in the distribution of these two rocks: the larger boulders on the asteroid's surface were blue, while the fine-grained remnants around them were red. They also found that the blue craters were younger than the red ones, as if the Hayabusa-2 impact had broken through the red top layer and exposed the blue rock beneath, mixing colors and throwing up a lot of red dust.
The blue rocks probably arose after some of the reddish sand was thrown out of the equatorial regions of Ryugu due to rotation, as well as due to the formation of new craters. Presumably, over time, forces acting on the asteroid's surface - such as impact or exhaustion - have mixed the red and blue rocks. However, in order to finally confirm these conclusions, it is necessary to wait until Hayabusa-2 delivers samples to terrestrial laboratories.
Previously, scientists found ribose and other sugars in two asteroids that can participate in the formation of RNA and DNA molecules, and the European Space Agency telescope helped to find out that the asteroid Hygea fits all the criteria for a dwarf planet.