Abstract and subjects
Perseverance images of a delta on Mars The Perseverance rover landed in Jezero crater, Mars, in February 2021. Earlier orbital images showed that the crater contains an ancient river delta that was deposited by water flowing into a lake billions of years ago. Mangold et al . analyzed rover images taken shortly after landing that show distant cliff faces at the edge of the delta. The exposed stratigraphy and sizes of boulders allowed them to determine the past lake level and water discharge rates. An initially steady flow transitioned into intermittent floods as the planet dried out. This history of the delta’s geology provides context for the rest of the mission and improves our understanding of Mars’ ancient climate. —KTS
Images taken by the Perseverance rover shortly after landing show the stratigraphy of an ancient river delta.
Observations from orbital spacecraft have shown that Jezero crater on Mars contains a prominent fan-shaped body of sedimentary rock deposited at its western margin. The Perseverance rover landed in Jezero crater in February 2021. We analyze images taken by the rover in the 3 months after landing. The fan has outcrop faces, which were invisible from orbit, that record the hydrological evolution of Jezero crater. We interpret the presence of inclined strata in these outcrops as evidence of deltas that advanced into a lake. In contrast, the uppermost fan strata are composed of boulder conglomerates, which imply deposition by episodic high-energy floods. This sedimentary succession indicates a transition from sustained hydrologic activity in a persistent lake environment to highly energetic short-duration fluvial flows.