Vesta

Vesta, formally numbered 4 Vesta, is a large asteroid in the main asteroid belt with a differentiated interior and basaltic crust. It preserves evidence that a small body could melt and separate into internal layers early in Solar-system history, making it a useful comparison with the larger terrestrial planets.^[ref]

The Dawn spacecraft mapped its surface and measured its reflected spectrum and gravitational field. Large impact basins expose material from beneath the original surface, while spectral measurements constrain mineral composition. Changes in the spacecraft's radio-tracked orbit constrain the distribution of mass. The inference of an interior structure combines these observations with physical models; a surface image alone cannot locate a buried core.

Basaltic meteorites provide a complementary laboratory record. Comparing their mineral signatures with remote spectra tests the connection between recovered rock samples and a parent body. Agreement is evidence about composition and origin, whereas reconstructing the body's full cooling and impact history requires additional geological constraints.