Geological diversity of paleolakes in the NW Arabia Terra, Mars: implications for Tianwen-3 sample return mission

Hundreds of paleolakes have been identified across Mars. Due to their unique morphological features and astrobiological significance, paleolakes have been selected as the landing sites of several Mars in-situ exploration missions. Tianwen-3 is China’s second Mars mission and plans to return more than 500 g Mars samples around the year 2030. Its primary scientific objective is to search for signs of life and evaluate the habitability of Mars. To achieve this goal, choosing a suitable landing site is fundamentally important. Considering the engineering constraints of the mission, we proposed that paleolakes in the northwest Arabia Terra, which has a prolonged history of aqueous activity, are ideal candidate landing sites. However, detailed identification and geological characterization of paleolakes in this area have not been conducted.

In this study, we utilized multi-source remote sensing data to investigate the geomorphology, mineralogy, and age of paleolakes in northwest Arabia Terra. A total of 46 crater-hosted paleolakes are identified, with 38 of them being reported for the first time. Sedimentary landforms such as fan-shaped deposits and layered deposits in the lake basins were mapped, and new outcrops of aqueous minerals including carbonates and sulfates were discovered. Age determination results found that lacustrine activities extended from the Middle Noachian to Amazonian. Based on our results, we discussed the geological diversity of the paleolakes and proposed three high-value candidate landing sites for the Tianwen-3 mission. Our work will provide clues to the habitability and geological evolution of Mars, as well as support the implementation of Tianwen-3 mission.