I did not wait for the guests: the asteroid Bennu gave astronomers an unpleasant surprise

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The NASA space agency has collected a large conference the day before, during which the experts talked about several discoveries related to the asteroid Bennu, which OSIRIS-REx "met" in December of the last year.

Thus, during the current mission, for the first time in history, scientists "examined" the plumes of erupting particles from the surface of an asteroid near the Earth.

"The opening of the cycle [частиц] – one of the biggest surprises in my scientific career. Bennu surprises us already, even if our fascinating journey has just begun ", he shared the joy of the principal investigator of the OSIRIS-REx mission Dante Laurett (Dante Lauretta) of the University of Arizona.

Shortly after the discovery of the particle plume (this happened on 6 January), the experts increased the frequency of the observations. As a result, in the next two months, they also found other plumes of particles. The size of the objects observed varies from a few to tens of centimeters.

Many particles were thrown out by Bennu, but scientists traced the trajectories of some of them. They circled the asteroid like satellites, and then returned to its surface.

Initially, members of the OSIRIS-REx mission noticed a plume of particles in images taken with a probe from a distance of about 1.6 kilometers. Later, experts concluded that they do not pose a danger to the spacecraft. To date, the observations continue.

Another discovery concerns the surface of Bennu: it turned out to be more "approximate" than expected. The experts did not expect to see such a large number of large blocks on the surface of the asteroid.

This forced the scientists to change their plans to collect soil samples from the space tramp. We recall that the probe in 2023 should deliver soil samples of asteroids to Earth. And for this he needs a platform with a radius of about 25 meters.

But instead of flat areas covered with dust, scientists have found thousands of small boulders and more than two hundred on the surface of the asteroid, which reach a width of ten meters.

Now the researchers have started looking for suitable options with a much smaller radius. The mission team is also developing an updated approach called TAG Bullseye, to point the machine at smaller sites where it is possible to collect samples.

Note that the scientists expected to see a relatively flat surface with several large boulders. These were the initial estimates of the Bennu surface, which was based on ground observations of the thermal inertia of the asteroid (its ability to conduct and store heat) and on radar measurements.

Now, when OSIRIS-REx "saw" the surface of the nearby asteroid, the experts realized that their predictions were wrong. This means that the computer models used today to interpret data do not adequately evaluate the surface characteristics of small rocky asteroids. Now a team of experts is examining these models, having the data on Benn in their hands.

However, experts believe that all the current difficulties will not prevent them from facing the task.

On the surface of Bennu, scientists have discovered thousands of small and about 200 large boulders.

We also note that the scientific team of the OSIRIS-REx mission succeeded in making many other discoveries concerning Bennu. Scientists talked about some of them on Tuesday at the 50th lunar and planetary conference in Houston and in a special collection of articles published by the journal Nature.

In particular, the team directly observed a change in Bennu's rotational speed as a result of a phenomenon known as the Yarkovsky-Okifi-Radzievsky-Paddak effect (YORP effect).

We recall that the OSIRIS-REx device was launched in space in 2016. During his journey, he traveled about 130 million kilometers separating an asteroid from our planet (and even more, given that the spaceship did not move in a straight line) .

On December 3, 2018, OSIRIS-Rex reached an asteroid and went into orbit around it, as described by the authors of the Vesti.Nauka project (nauka.vesti.ru).

The probe must spend more than a year in the orbit of the asteroid, studying it with the help of on-board equipment. This will help him with a set of scientific instruments.

It is believed that Bennu may contain material that has been preserved in its original form by the formation of the solar system. In fact, for this reason, it is of great interest to science.

As Lori Glaze, acting director of the NASA planetary sciences division, says, the samples will help scientists answer some of the most important questions about how the Earth and its environment were formed, on water sources and organic molecules on our planet, resources, available in the space near the Earth and will also improve the understanding of the nature of asteroids that could fall on Earth.

According to the experts of the American Space Agency, Bennu is one of the most dangerous objects for our planet.

The probability that it falls on Earth in the period from 2169 to 2199 is 1: 4000 (high enough by cosmic standards), and its collision with our planet would be as powerful as a 2700 megatonn bomb explosion trotilo equivalent.

By the way, "Vesti.Nauka" previously wrote about other similar missions: the delivery to the Earth of soil samples of the asteroid Itokawa and of the Japanese probe Hayabusa-2, whose purpose is to collect the Ryugu asteroid. .

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