However, it is not known what the particles are. In general, water vapor erupts from comets made of ice as they approach the sun, but active asteroids and asteroids that erupt are rare. However, Benne is considered to be a member of the “active” asteroid that has been discovered only 12 out of 800,000 asteroids so far.
OSIRIS-REx spawned basketball-sized "particles" at a rate of several centimeters to several meters per second at least 11 times during the five weeks from January 11th to February 18th.
(embed) https://www.youtube.com/watch?v=YxooQ_68M08 (/ embed)
NASA's control team was initially worried that the release of this particle could affect the OSIRIS-REx meeting Benne. However, it turns out that the possibility is very low, and after that, it is trying to find the source of the particle by calculating the trajectory of the particle. Many of the particles are released into outer space and travel in orbit around Bennes for months to years. Some fall on the ground in Benne.
There are two hypotheses for the reason why such particles erupt from Benne. One is the theory that a small substance called meteor material collides with Benne and releases particles, and the other is thermal stress breakdown due to changes in the surface temperature of Benne's "day" and "night" rotating in 4.3 hours. The phenomenon called.OSIRIS-RExWe have also observed the release of water vapor from Benne. This can also occur when a clay layer containing moisture is exposed due to cracks on the surface, and cracks may also be related to particle ejection.
NASAWhen collecting OSIRIS-REx samples in Bennes scheduled for summer 2020,I also want to collect the released particles. And if it can be brought home, it will “almost certainly deepen the understanding of the asteroid”. NASA plans to collect at least 60g and up to 2kg of samples from Bennes and return to Earth in September 2023.
By the way, it has been pointed out that the asteroid Benne may approach the Earth 8 degrees between 2169 and 2199, and may collide with the Earth in any of them. Although the probability is 1/2700 at the maximum, this is a higher probability than any other celestial body known so far.