Meteorites are messengers from interplanetary space that preserve information about the earliest moments of our Solar System. Yet once they land on Earth, their story does not stop: it continues evolving. Recently, a Belgian-Chilean research team, including two members of BLU (G. A. Pinto and V. Debaille), has shown that salts can form within meteorites after they reach Earth’s surface.
In one of the driest places on Earth, the Atacama Desert, meteorites undergo subtle but powerful transformations. Tiny cracks and pores within these rocks become pathways for salt-rich fluids, which circulate and then evaporate, leaving behind minerals such as sulfates, carbonates, and chlorides. These are not remnants from space, but products of terrestrial alteration.
By studying several carbonaceous chondrites (Ornans-type) collected from different regions of the Atacama Desert, the team found that the types of salts present reflect the local environment where each meteorite landed. Some samples bear the signature of ocean-derived salts and moisture carried by wind over nitrate soils, while others reflect interaction with inland calcareous soils influenced by sporadic rainfall. An evaporitic mineral appears repeatedly in these meteorites: anhydrite, a water-poor polymorph of calcium sulfate. Its presence suggests formation under extremely dry conditions, where even minimal moisture quickly evaporates. These findings shift the perspective from viewing meteorites as static objects to seeing them as dynamic records of their surroundings.
Similar minerals have been identified on Mars, suggesting that dry, salt-rich environments there could also preserve traces of organic material. These results suggest that salt-rich, extremely dry environments may actually help trap and protect organic matter, even if it is not biological in origin, offering clues in the ongoing search for past habitability on the red planet.
(Photo 1: Imagen Credit: Rodrigo Martínez, Museo del Meteorito) (Photo 2: Fig. 9 in Pinto et al., 2026; Icarus Journal)
