At the end of 2018, the space probe OSIRIS-Rex entered the orbit of the asteroid Bennu and revealed interesting features about its structure. It would seem that with such proximity of the apparatus, all the new discoveries should be made only by means of its onboard equipment, but no. Researchers at NASA found that the rotation rate of the asteroid is constantly growing — this feature was not recorded by the probe, and ground-based telescopes and Observatory “Hubble”. After this discovery, researchers have new questions and assumptions.
Asteroid Bennu is moving at the speed of 101 000 km/h. however, he every 4.3 hours makes a full rotation around its axis. After analyzing the data for 1999, 2005 and 2012, researchers at NASA came to the conclusion that the speed of the object gradually increases. According to their calculations, every century the speed of rotation is increased by one second.
Such acceleration may seem small, but since the age of Bennu is estimated at 4.5 billion years, this feature can tell a lot about the history of the asteroid. For example, the acceleration could be the cause of many irregularities, and in the distant future, he can simply fly apart.
The researchers have several theories about the causes of the acceleration of rotation of the object. One of them says that the speed is enhanced by reducing the diameter of the asteroid with the loss of cobbles is about the same thing happens when a skater spreading her arms to accelerate. Also, the acceleration can be explained by the occurrence of YORP-effect, when the rotational speed is affected by sunlight.
NASA intends to further explore this feature of the asteroid. For more accurate information, the researchers will use the equipment OSIRIS-REx. With all this, the main objective of the unit is the collection of soil samples to prevent damage to the equipment, NASA plans to begin collecting in the most secure place. To do this, she asked the online community to help with the mapping of the surface, where every stone.
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