Asteroids Bennu and Ryugu similar to a spinning top
The spacecraft that had visited both an asteroid may give a clue to the formation process of these space rocks.
New images Bennu (Bennu – left photo), which were made in close proximity, confirmed that an asteroid has the shape of a spinning top. This species is characterized by the bulging Equatorial ridge, are other asteroids of similar size in the Solar system, including Ryugu (Ryugu – right), which is now being investigated by the Japanese probe Hayabusa2. Spaceship NASA OSIRIS-REx to Bennu arrived 3 Dec.
New studies of both the rotation of the asteroid around its axis is too slow to give them tcou form, says the Manager of the mission Hayabusa2 Makoto’s Yoshikawa from the Japanese space Agency JAXA. If the rotation is fast enough, the momentum could push loose stones to the equator, giving the asteroid the shape of the top. But Ryugu rotates on its axis only once every 7.6 hours. New data show that Bennu makes one revolution every 4.3 hours.
Now, when the spacecraft research and Bennu, and the Ryuga, scientists want to know why amazing shapes of asteroids. “The dream of asteroideae – to unravel this mystery,” said December 10, principal investigator of OSIRIS-REx from University of Arizona, Tucson Dante Lauretta at a press conference at the meeting of the American geophysical Union.
Speed asteroids could one day be much higher, but eventually decrease due to a phenomenon called the YORP effect. This occurs when particles of light hit the Sun on various types of surface materials of the asteroid. This light is reflected off certain materials, giving some momentum, which may be a counter-rotation of a celestial body. Other materials absorb the light and then radiate it back as heat, creating a force that can change the rotation of the asteroid and thus its shape.
Since OSIRIS-REx continues to follow Bennu, it will compare the observed rotation rate of the asteroid with a width of almost 500 meters with surface-based observations, in the hope to track how its rotation may change with time. These observations can show whether once rotation Benn fast enough to give it the shape of the top.
However, Benn, and Ryuga are not identical twins. At the equator Benn has much more square shape, as shown by new data, whereas the Ryuga has a circular shape. Although both asteroid can boast Equatorial ridge, strewn with craters and boulders, Ryugu it is much more pronounced, says there’s Yoshikawa.
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