Large‐Scale Troughs on Asteroid 4 Vesta Accommodate Opening‐Mode Displacement

What is it about?

The camera on the Dawn spacecraft captured two sets of large linear depressions, or troughs, on asteroid Vesta. Previous studies hypothesized that these troughs are fault-bounded valleys with a distinct scarp on each side that together mark the downward drop (sliding) of a block of rock. However, cracking of rock can also form troughs, an origin that has not been considered before. Structures formed by sliding and cracking form different map patterns, have different morphologic expressions, and are controlled by different stresses acting on the rock volume. Although trough shape does not display any diagnostic map patterns, the morphology of the troughs is consistent with cracking because troughs are widest at the middle and narrow toward both ends. Calculated stresses are not favorable for sliding to be triggered within the uppermost ∼3–55 km of Vesta's rock volume, but instead, the physics shows that rocks are favored to crack apart. Therefore, the formation of these troughs must involve the opening of cracks, which is also important for understanding landforms on other small planetary bodies elsewhere in the Solar System.

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Photo by Viktor Talashuk on Unsplash

Photo by Viktor Talashuk on Unsplash