Origin of the asteroid Bennu had rivers, according to new evidence


Full of new revelations over the past few months, the asteroid Bennu has become the darling of scientists. But that has reasons. On October 20, NASA’s OSIRIS-REx mission will collect samples of the asteroid. It will bring them to Earth (their arrival will only be in 2023). Now, with the discovery that the father of the asteroid Bennu possessed rivers, he becomes even more fascinating.

Bennu has remained almost untouched since the formation of the solar system, although there is a small exchange of materials with other bodies. Either way, it doesn’t even compare with the amount of material received by Earth. Therefore, studying Bennu would help us to understand a little of Earth’s past. Searching for chemical elements there would bring insights into the emergence of life on our planet.

At the end of 2018, OSIRIX-REx entered the orbit of the asteroid. Since then, it has collected data from above, and has not yet landed. But landing and collecting materials are close at hand. But before diving into the unknown, the researchers in charge try to find out what exactly they will find there, that’s why it takes so long.

Bennu’s father and the rivers

When it comes to evidence of rivers, it is not about Bennu itself, but about his “ancestors”. The asteroid is, in short, a pile of space debris that arose after the collision of two other bodies a long time ago. The carbonate veins, evidence of running water, are probably from the time when Bennu did not yet exist. The work was described in a series of six articles, published in journals Science e Science Advances.

Evidence indicates the presence of hydrated material, that is, a little water until today, in addition to organic material. They will likely be present in the sample collected on October 20. The shape of the carbon present in this material, as scientists believe, is similar to that found quite frequently in organic matter on Earth.

Asteroid Bennu. (Image credits: NASA / Goddard / University of Arizona).

Tracing carbonates

“The abundance of carbon-containing material is a major scientific triumph for the mission. Now we are optimistic that we will collect and return a sample with organic material – a central objective of the OSIRIS-REx mission ”, he explains in a Press release Dante Lauretta, principal investigator for the mission at the University of Arizona, in the United States.

It is worth remembering that the presence of organic material does not necessarily represent life. Organic material is also created by geological means. And this is exactly the origin of the carbonate minerals of Bennu – geological. The aim is not to discover life outside of Earth, but to find the means by which life on Earth came about. Organic matter precedes life, not the other way around.

Carbonate minerals precipitate, commonly, when in hydrothermal systems. This is how they generate a trail with the passage of water, forming the veins. From above, these veins then look like shiny lines. It is in this region that the landing is scheduled. “If the veins in Bennu are carbonates, the fluid flow and hydrothermal deposition in Bennu’s parent body would have occurred on scales of kilometers for thousands to millions of years,” explain the researchers in one of the studies.

Pure material

In addition to the origin of the asteroid Bennu had rivers, scientists also found that the region of the Nightingale crater, where the spacecraft will land, is quite virgin. Only recently has it been exposed to space, with the disintegration of Bennu. This means that the material is quite pure, making it considerably faithful to what was the composition of the bodies in our region of the solar system millions or billions of years ago.

Analyzes of the gravitational field still indicate that the distribution of matter by Bennu is quite irregular. Therefore, some regions probably have very different densities from each other. Scientists are curious to understand a little more about Bennu. The probe is expected to depart from the asteroid in mid-2021 and will arrive on Earth in September 2023.

The studies were published in journals Science e Science Advances. With information from OSIRIX-REx Asteroid Mission/NASA e Futurism.


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