Science (United States): NASA has had difficulty in taking samples due to the mysterious activity of the Political Asteroid | New York Times


Woodlands, TX – The NASIRIS-Rex mission of NASA, whose goal is to fly on Benn's asteroid, study it and deliver ground samples to the Earth, has always been considered a difficult operation, for which it is not known. they were guarantees. But the mission becomes more risky than ever after the new discoveries related to the object of study – a space asteroid five times bigger than an American football field, which rotates in an orbit near the Earth. Today at the international scientific conference on planetology (Conference on lunar and planetary science), as well as in a series of articles published in the journal Nature, the mission reported that the surface of Bennu is nothing but a stony plain, but a mixture of 200 or larger boulders. And the distance between them is not large enough to allow the manipulator to collect samples of his surface soil.

At the beginning of this year, a $ 800 million spacecraft began to orbit Bennu, and the asteroid immediately started "throwing up" surprises. On January 6, the team discovered the emission of small particles from the surface of the asteroid in the form of a plume. The following month, there were ten similar issues. Bennu is not just frozen fragments of cosmic bodies formed as a result of past cosmic collisions, but one of a dozen known "active" asteroids. "[Это] one of the biggest surprises of all my research times, "says Dante Lauretta, scientific director and mission planetologist at the University of Arizona in Tucson." We are seeing Bennou regularly spewing material into space. "

First, while observing the Bennu asteroid from Earth, scientists have suggested that its surface is made up of small pebbles that cannot retain heat. The space probe has been designed for sampling from such a smooth surface and, to approach the surface of the asteroid, it needs a platform free from dangerous interference in the form of a circle with a diameter of 50 meters. According to the mission, there is no such place on the surface, but there are several small areas with no boulders where the probe could take samples. Considering how well the spacecraft has accomplished its maneuvers to date, "we want to try to reach the center of the site," says Rich Burns (Rich Burns), project manager for OSIRIS-REx from NASA's Goddard Space Flight Center in Greenbelt, Maryland .

The OSIRIS-REx mission at all stages is performed with the observance of precautionary measures and does not imply rushed actions. Unlike the Japanese "high-speed" mission that uses the Hayabusa-2 probe (Hayabusa2), which took samples from the surface of the asteroid near the Ryugu land six months after entering its orbit, the scientists working at the # 39 of the OSIRIS-Rex mission plan took samples from Bennu emerges in July 2020, that is a year and a half after the start of work in its orbit. According to Dante Loretta, the plan and deadlines have not changed. The researchers expect to choose a site for sampling by this year's summer. There is still much to learn about this rotating dome-shaped asteroid and, above all, about emissions in the form of a plume, in which particles of a substance the size of a small coin can "fly out" at speeds up to several meters per second.

Immediately after the OSIRIS-REx device entered Bennu's orbit, the asteroid was as close to the Sun as possible. On other known active asteroids, found in the asteroid belt between Mars and Jupiter, emissions similar occur during the approach to the Sun. Perhaps they are associated with this approximation and, apparently, due to the fact that the water ice turns into steam. But dozens of different hypotheses must be studied, says Loretta. "Now we don't know the answer."

The abundance of impact craters on the surface of ribbed Bennu suggests that the age of the asteroid is about a billion years, that is, it is older than previously thought. The craters also indicate that Bennu acquired a dome shape at the beginning of its existence, and not later as a result of the rotation under the influence of the sun. And there are signs that the material at the poles of the asteroid "slips" in the direction of the equator, which indicates geological activity.

Although many of these mysteries intrigue scientists, the ultimate goal of the mission is to deliver to the Earth the maximum amount of material from the surface of the asteroid. This should happen in 2023. But, according to Loretta, "this task has become much more difficult when we saw the true nature of Bennu's surface".

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