A probe on Mercury used for the purpose of "surface-space-environment-geochemistry-and-ranging" abbreviated as the MESSENGER mission to Mercury, resulted in the discovery of geological structures known as hollows. Such landforms are quintessentially extraterrestrial with no close counterpart on the airless silicate bodies. Astrogeologists had used multispectral images and geochemical measurements via probes to show how hollows formed by the disintegration of volatile-bearing minerals.