In the solar system, asteroids are not uncommon. In general, these asteroids orbit the Sun within the solar system, somewhat similar to the eight planets, but these asteroids are very small in size, much smaller than the eight planets. Moreover, the distribution of these asteroids is still relatively regular, and the vast majority of asteroids in the solar system are concentrated in the asteroid belt between the orbits of Mars and Jupiter, and some asteroids are located in the more distant Kuiper belt. In the Kuiper Belt, scientists have found that some asteroids are larger in size, such as Genesis, which is nearly 1280 kilometers in diameter, and Thatos is even about the same size as the former ninth planet, Pluto, and these huge asteroids challenge Pluto's status. These larger asteroids have now been reclassified as dwarf planets.
Since most asteroids are concentrated between the orbits of Mars and Jupiter, scientists at first thought that these asteroids might be debris from the shattering of a planet between Mars and Jupiter. But later, after research, scientists found that these asteroids were not once assembled, and the total mass of all the asteroids in the asteroid belt was actually very small, only about 4% of the Moon, which was smaller than Pluto. So, the prevailing view now is that these asteroids should be remnants of the early days of the solar system. Of course, the formation time of asteroids is billions of years, and we are currently only speculating about the origin of asteroids, in order to better study asteroids, scientists have thought of some ways, such as launching probes to sample asteroids for research.
Among the hundreds of millions of asteroids, each asteroid can be said to be very unique, worthy of our study, can become a target for human sampling, asteroids must have a lot of uniqueness. For example, the Ryugu asteroid, which is about 300 million kilometers away from the earth, is more special, and the Ryugu asteroid may contain a lot of organic matter and aqueous minerals, and its rotation period is only 7.5 hours, which is slower than the general asteroid rotation.
On December 3, 2014, Japan launched an H-2A carrier rocket at the Tanegashima Space Center to send the Hayabusa2 probe into space and begin a journey to Ryugu asteroid to sample and return to Earth. After more than three years of flight, the Hayabusa2 probe arrived near the Ryugu asteroid at the end of June 2018 and began exploring it.
The Hayabusa2 probe was originally scheduled to land on the surface of the Ryugu asteroid in October 2018 to collect samples, but the situation on the surface of the Ryugu asteroid is more complicated, the surface is covered with a large amount of rock, and in order to ensure that the mission is foolproof, Japan has to postpone the landing time on the surface of the asteroid and continue to observe the Ryugu asteroid in order to find a more suitable landing site. After a period of observation, scientists found 2 landing sites on the surface of the Ryugu asteroid, and the rocks near these 2 landing sites were less than 60 centimeters in size, one of which was more spacious and one was relatively narrow.
In February 2019, the Hayabusa2 probe successfully landed on the surface of the Ryugu asteroid, successfully grabbing a small cloud of dust on the surface of the Ryugu asteroid, while also discovering hydrated minerals on the surface of the Ryugu asteroid. The discovery has once again convinced many scientists that Earth's water may have been brought by these asteroids billions of years ago. Then, in April 2019, the Hayabusa2 probe fired a metal bomb at the surface of the Ryugu asteroid, hitting a crater about 10 meters in diameter on the surface of the Ryugu asteroid, and the probe subsequently collected the material stirred up by the metal bomb.
At this point, the Ryugu asteroid not only collected samples from the surface of the Ryugu asteroid, but also collected samples from the interior of the asteroid, which are theoretically different, the surface samples after billions of years of weathering, may no longer be the original appearance, and the internal samples are rarely affected by the solar wind, so relatively primitive, can let us better understand the early stage of the solar system.
In November 2019, the Hayabusa2 probe ended its mission to explore the Ryugu asteroid and began returning to Earth. After nearly a year of flight, the Hayabusa2 probe returned to Earth's vicinity in December 2020 and released a recovery capsule containing ryugu asteroid samples to Earth. On December 6, 2020, the recovery capsule landed in the southern desert of Australia, and scientists subsequently recovered the capsule and brought it back to Japan. The Hayabusa2 probe began a new journey into space after releasing the recovery capsule, planning to reach the next asteroid in 2031 for exploration. Although Ryugu asteroid is only about 300 million kilometers away from Earth, the Hayabusa2 probe has orbited it for a long time, and the Hayabusa2 probe has traveled 5.2 billion kilometers from launch to return to Earth.
The hayabusa2 probe's sample module is divided into three compartments, A, B and C, of which A is used to store the first collected sample, that is, the dust collected from the surface of the Ryugu asteroid, and the C chamber is used to store the second collected sample, which comes from the interior of the Ryugu asteroid and is the sample that bounces out of the metal bomb when it hits. Due to the different locations of the samples collected, the samples of cabin A and the samples of cabin C are also different, among which the sample size of cabin A is relatively small, all of which are some sand grains with a diameter of millimeters, while the sample size in cabin C is relatively large, and some of them are small stones close to 1 cm. Not only that, but in the C-chamber, scientists also found some silver substances similar to aluminum foil.
This situation has attracted a lot of attention, flying for 6 years, flying a mileage of 5.2 billion kilometers, Hayabusa2 probe not only "violent mining" on the asteroid 300 million kilometers away, brought back asteroid samples, but also brought some suspected man-made objects. What's going on? Some scientists believe that this silvery material similar to aluminum foil may have fallen from the Hayabusa2 probe during sampling, after all, only the Hayabusa2 probe is currently detecting near the Ryugu asteroid.