This Wednesday (9), NASA revealed to have made an important discovery about the asteroid Bennu, reported by the scientific team of the OSIRIS-REx mission. According to the researchers, the celestial body is regularly discarding material, throwing particles, rocks and other pieces of itself.
The behavior, observed for the first time since the probe was launched in 2016, has given scientists an unprecedented view of a space rock as it moves through space. The novelty was described in a series of articles published in the Journal of Geophysical Research: Planets.
These fugitive particles from Bennu (the animation below shows some of them happening) were discovered almost unintentionally by the chief astronomer of the mission Carl Hergenrorther. Observing the images of the constellations made by the spacecraft, he noticed the presence of what appeared to be hundreds of extra stars. Intrigued, he made a more detailed inspection with the help of technology and unraveled the mystery: they were not stars, but pieces of the asteroid coming loose.
In fact, the American space agency has observed and tracked more than 300 events of ejection of materials from the celestial body such as this most recent, since the arrival of OSIRIS-REx to the “asteroid at the end of the world”. However, scientists did not know what it was about, only finding out now.
Tiny particles prevented discovery
The reason why NASA had not yet noticed this disintegration of Bennu is the tiny size of most of the fragments that escape it, making it difficult to observe from Earth. While some particles escape into space, others orbit the rock and most fall back into it.
“To give you an idea, all 200 particles that we observed during the first event after arrival would not fit on a 10 x 10 cm tile,” compared Hergenrorther.
He believes that meteoroid impacts and thermal stress cracks during its rotation (the asteroid heats up during the day and cools down at night) are the main causes of the phenomenon.