Events
Physics Colloquium: Dr. Masatoshi Hirabayashi (AU Aerospace Engineering) |
| Time: Sep 20, 2019 (03:00 PM) |
| Location: Leach Science Center 3142 |
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Details: Why do many small sandcastles look like a diamond? Implications from recent observations from two asteroid sample return missions, Hayabusa2 and OSIRIS-REx. Studies have shown that asteroids are rubble piles with irregular shapes. Such irregularities of large asteroids may be attributed to collisions and tidal effects. On the other hand, those of small bodies may have resulted not only from these processes but also from fast rotation. This rotation-driven evolution is now considered to be caused by solar radiation pressure. A typical asteroid that is affected by fast rotation may have a round shape with a unique equatorial ridge, which is known as a top-shape. Recent observations of Ryugu by JAXA's Hayabusa2 and Bennu by NASA's OSIRIS-REx revealed the unique geophysical features of these top-shaped asteroids. Here, we use a finite element model (FEM) technique to analyze the failure modes and conditions of Ryugu and Bennu to explore the shape evolutions of these asteroids. Our analysis suggests that the magnitude of their spin conditions is critical to developing the current geophysical conditions of these top-shaped asteroids. |