Using simple concepts from granular physics, scientists managed to explain the diamond shape of the Bennu and Ryugu asteroids and showed that these small bodies acquired this shape early in their formation.
Scientists from Okinawa Doctoral College of Science and Technology (Oist) and Rutgers University used simple concepts from physicsto explain the curious of two .
These two asteroids,and , were explored by a space probe, respectively Osiris-REx and Hayabusa 2, which facilitates their study. These two diamond-shaped asteroids are ” Which means they are made up of many small pieces of rock material that are loosely held together by . These are thus essentially grains that interact with each other, such as of our beaches.
Tapan Sabuwala, first author of the article published in Granular Matter and researcher at the Fluid Mechanics Unit of Oist, explains: “ Previous models attributedto the forces caused by the rotation, which caused the displacement of the from the poles to the . But, when asteroids were simulated using these models, the shape was flattened or rather than diamond, so we knew something was wrong. We discovered that these models were missing a key ingredient, the deposit of material. And a simple model of granular, normally used for the deposition of grains such as sand or , could predict the observed shape ».
From sandcastles to asteroids
Imagine pouring sand or sugar into a funnel, a cocktail of different strengths will cause it to. The Granular specialists can predict the shape of the pile based on the different forces acting on the grains. Dr. Sabuwala, alongside Professor Pinaki Chakraborty, who heads the unit, and Professor Troy Shinbrot, of Rutgers University, transferred these ideas to asteroids.
Tapan Sabuwala specifies that, on these asteroids, gravity iscompared to that felt by a pile of sand on a beach and that it therefore has ” had to take this into account in our model, along with the fact that the rotation of the asteroid also plays an important role ».
So instead of the conical shape seen in the accumulation of grains on Earth, the forces at work on the asteroids produced diamond shapes. The centrifugal force, caused by the rotation, decreased near the poles of the asteroids, causing matter to accumulate there and producing their distinctive shape. Another important distinction of this model (compared to previous ones) is that it suggests that these “piles ofDidn’t start out as a sphere that warped into a diamond shape. On the contrary, the accumulation of debris led to this diamond shape very early in the formation of the asteroid, and any subsequent remodeling was minimal. Additionally, the idea that these diamond shapes were produced during the early stages of the asteroid’s formation, although at odds with previous models, is consistent with recent observations.
The researchers then showed the accuracy of this model through simulations and found that the simulated asteroids acquired this distinctive diamond shape, bolstering their theory.
What you must remember
- Bennu and Ryugu are two diamond-shaped “rubble heap” asteroids.
- Using a simple granular physics model designed to explain the flow of grains like sand and sugar, researchers have succeeded in explaining the overall shape of these asteroids.
- They then simulated the asteroids using this model, which reinforced their hypothesis.
- Their research suggests that asteroids acquired this diamond shape very early in their formation, which is at odds with previous models.