101955 Bennu is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth. On 3 December 2018, the OSIRIS-REx spacecraft arrived at Bennu after a two-year journey. In October 2020, OSIRis-REX successfully touched down on the surface of Bennu and collected a sample.
About 101955 Bennu in brief
101955 Bennu is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is named after the Bennu, the ancient Egyptian mythological bird associated with the Sun, creation, and rebirth. On 3 December 2018, the OSIRIS-REx spacecraft arrived at Bennu after a two-year journey. It orbited the asteroid and mapped out Bennu’s surface in detail, seeking potential sample collection sites. Bennu has a roughly spheroidal shape, resembling a spinning top. Its axis of rotation is tilted 178 degrees to its orbit; the direction of rotation about its axis is retrograde with respect to the orbit. It has a low geometric albedo of 046±10m, which is in line with other studies of minor planets. No emission from a potential coma has been detected around Bennu. In October 2020, OSIRis-REX successfully touched down on the surface of Bennu and collected a sample using an extendable arm, secured the sample and prepared for a return trip to Earth. The asteroid was given the provisional designation 1999 RQ36 and classified as a near-Earth asteroid. The name Bennu was selected from more than eight thousand student entries from dozens of countries around the world who entered a \”Name That Asteroid!\” contest run by the University of Arizona, The Planetary Society, and the LineAR Project in 2012. It was based on the Yarkovsky–O’Keefe–Radzievskii–Paddack effect, or the YORP effect, which puts a limit on the radius of dust within a radius of 4750km of the asteroid’s orbit.
The Asteroid is a potentially hazardous object that is listed on the Sentry Risk Table with the second-highest cumulative rating on the Palermo Technical Impact Hazard Scale. Its surface is rougher with more than 200 boulders larger than 10 m on its surface, the largest of which is 58 m across. The boulders contain veins of high-albedo carbonate minerals believed to have formed prior to the formation of the Asteroid due to hot water channels on the much larger parent body. There is a well-defined ridge along the equator that suggests that fine-grained regolith particles have accumulated in this area, possibly because of its low gravity and fast rotation. Observations by the OSIREx spacecraft has shown that Bennu is rotating faster over time. On 18 June 2019, NASA announced that it had closed in and captured an image from a distance of 600 metres from Bennu’s surface. It will return its samples to Earth in 2023 for further study. In 2013, Astrometric observations between 1999 and 2013 have demonstrated that its rotational axis is influenced by the YARKovsky effect, causing the axis of its axis to tilt by about 19% during each rotational period. The rotation period of this minor planet was measured and found to vary by approximately 19% each time.