According to Science and Technology Daily news on September 20, foreign media reported on the 19th that rock samples from an asteroid named "Bennu" will be brought back to Earth for analysis on the 24th. It is expected to carry 250 grams of rock materials collected in 2020.NASA scientists predict that Bennu may hit the Earth on September 24, 2182 (159 years from now),The potential impact of the collision is estimated to be equivalent to the explosive energy of 22 atomic bombs.
This asteroid was discovered in 1999. It is about 492 meters in diameter and "passes by" the Earth every six years. Although it does not pose a direct threat, its orbit intersects with that of Earth, so Bennu is classified as a potentially hazardous asteroid.
Originating from the original debris that formed our solar system some 4.5 billion years ago, Bennu is a diamond-shaped rock about 500 meters in diameter. Researchers believe that because of its fundamental properties, Bennu provides insights into the primordial matter that existed in the early solar system.
According to the Global Times, according to data from the National Aeronautics and Space Administration (NASA), the probability of an impact on this day is one in 2,700, or 0.037%.
For the past seven years, NASA has been developing a plan to move or destroy Bennu. On September 8, 2016, NASA launched the detector OSIRIS-REx. In 2020, OSIRIS-REx landed on Bennu's surface and collected rock material from a sample site called Nightingale.
Selected sampling sites for OSIRIS-REX viewed from 250 meters above Bennu. Image source: NASA/Goddard/University of Arizona/Nature Online
In order to conduct more in-depth research, a scientific research team under NASA sent a small detector to "Bennu" in October 2020. After collecting planetary soil samples,The probe is expected to return to Earth on September 24, 2023 local time.Scientists said that this is the first time that NASA has carried out such a mission. The samples collected have not been contaminated in any way and are valuable materials for studying the solar system and the origin of life.
Image source: Video screenshot
According to a previous report by Science and Technology Daily, shortly after the National Aeronautics and Space Administration's (NASA) OSIRIS-REx probe arrived at the asteroid Bennu, the OSIRIS-REx mission team discovered the mysterious phenomenon of Bennu continuing to eject particles outward.
After investigating various mechanisms that could have caused the ejection event, the team narrowed the possible causes down to three: meteor impact, thermal stress rupture and water vapor release.
Image source: NASA official website
Researchers said that meteor impacts are common in deep space near Bennu, and it is possible that small fragments of some space rocks could hit Bennu. The impact would shake up loose particles on Bennu, causing ejection activity. Thermal stress fracturing is also a reasonable explanation. Bennu's surface temperature changes drastically during its 4.3-hour rotation period. The temperature changes will cause the rock to fracture, eventually causing small particles to be ejected from the Bennu surface. The third possible reason is the release of water vapor. When Bennu's water-locking clay is heated, the pressure generated by the water vapor accumulates in the cracks and holes in the rock and is eventually released, causing the particles to be ejected.
NASA said it believes that scientists will give a more accurate explanation after physical samples are available for study.