The Perseverance rover provides new insights into the history and composition of the rocks on the floor of Mars’ Jezero crater, according to four studies. In Science , Kenneth Farley and colleagues describe the geologic formations on the crater floor, and the rover operations. They find that the crater floor consists of igneous rocks altered later by water. The rover collected core samples of these rocks, which are now stored aboard Perseverance for potential return to Earth. Also in Science , Yang Liu and colleagues investigate the petrology and composition of the Séítah formation, the lowest exposed geologic unit. They find that these igneous rocks are mainly made of coarse-grained olivine (an igneous mineral), indicating that they formed during slow cooling of a thick sheet of magma. The rock composition is similar to some Martian meteorites. In Science Advances , Svein-Erik Hamran and colleagues analyze a continuous radar scan captured by the rover during its initial 3-kilometer journey, revealing the crater’s bedrock stratigraphy and electromagnetic properties to a depth of about 15 meters below the surface. They suggest that the layered structure below the crater floor may indicate a history of igneous activity and of repeated exposure to liquid water. Also in Science Advances , Roger Wiens and colleagues analyze observations from the rover’s remote-sensing instrument during its first 286 Martian days on the Red Planet, revealing a volcanic terrain with layered rocks stratified below the surface by density and composition. They find that lower stratigraphic rock layers are richer in normative pyroxene and that the lowest observed layer is olivine-rich with the highest observed density.
Science
Aqueously altered igneous rocks sampled on the floor of Jezero crater, Mars
25-Aug-2022