The surface of the asteroid Bennu looks like a scree slope. This can be seen in pictures of the space probe "Osiris Rex" published by the American space agency NASA. Bennu is littered with boulders, many of them more than a meter in diameter. Bennu has a diameter of about 492 meters.
In seven research papers in the "Nature" group, scientists presented new insights into Bennu, including close-up shots. The deep black asteroid could come very close to Earth in more than 150 years. Although the impact risk is very low, the Nasa Bennu is one of the most dangerous asteroids currently known.
Research from Earth had initially suggested that Bennu has a rather smooth surface with a few larger boulders on it. The now discovered rocky surface make it more difficult to take soil samples from Bennu, the researchers report. The probe "Osiris Rex" should approach the asteroid so far that it can absorb samples.
DPA
Surface of the asteroid Bennu
Originally a place was to be found for it, which has no obstacles on a diameter of 50 meters. The researchers have now abandoned this plan due to the many boulders and look for a smaller zone. There is still some time left. By 2023, a capsule with the sample is to return to earth.
"This is one of the biggest surprises of my scientific career"
In the pictures, the "Osiris Rex" made by Bennu, can also be seen how he actively ejects particles into space. Some of these particles orbit the asteroid before returning to its surface, the research team reports. "This is one of the biggest surprises of my scientific career," said project leader Dante Lauretta of the University of Arizona.
In the past three months, "Osiris Rex" has studied the particle flows in more detail. The researchers first discovered them on January 6, 2019. They then decided to collect more data from the asteroid more frequently. In February and March, they registered further outbreaks. What exactly their cause is, they can not say yet. There is no danger for the spacecraft.
MORE ON THE SUBJECT
In addition, the researchers were able to prove that the speed with which Bennu revolves around its own axis changes. As it turns in the sunlight, it heats up unevenly and cools down again. This increases its rotational speed. The time it takes to spin around its own axis is reduced by one second every hundred years.
Earlier findings on Bennu, the researchers could confirm. They found magnetic iron ore on the asteroid. The find shows that the rock has come into contact with water, the researchers said. According to research, the water comes from a larger celestial body to which Bennu once belonged.
After about two years and more than 650 million kilometers traveled, "Osiris Rex" arrived at the asteroid in early December. Of the approximately one billion dollars (880 million euros) expensive mission, the scientists of NASA hope to gain knowledge about the origin of our solar system.