Question

The OSIRIS-REx spacecraft recently reached Bennu, a 492 meter wide rocky asteroid that is not believed to have a differentiated interior. Clearly suggest a reason why Bennu did not differentiate into distinct layers, which is common among larger asteroids, moons, and planets.

Answer 1

Bennu probably did not undergo differentiation into distinct layers due to its small size, which means it likely never generated or retained enough heat to melt and allow materials to separate by density. Its 'rubble pile' nature supports this lack of internal heating and differentiation, and it may have originated from collision debris.

Step-by-step explanation:

The reason why Bennu did not differentiate into distinct layers, unlike larger asteroids, moons, and planets, could be due to its size. Differentiation, a process where a celestial body separates into distinct layers such as a core, mantle, and crust, typically occurs in bodies that were once molten or partially molten. Larger bodies can retain heat from their formation longer, allowing for the melting and separation of materials by density.

In contrast, Bennu, with a diameter of only 492 meters, may have never generated or retained enough heat to melt and differentiate. Its description as a 'rubble pile' suggests it is made of loosely bound material that has not experienced significant internal heating or differentiation. Additionally, as many smaller asteroids are remnants of larger bodies that fragmented after collisions, Bennu could have formed from the debris of such events without undergoing differentiation.