Subsurface Habitable Environments Revealed by Mud Volcanoes in Utopia Planitia on Mars and Implications for China's Tianwen-3 Mission

The Vastitas Borealis Formation (VBF) has been hypothesized to represent sedimentary remnants of ancient northern martian oceans. Widely distributed pitted cones across VBF are interpreted as most likely mud volcanoes, whose source regions might have hosted habitable environments. Assuming these features are mud volcanoes, we constrained the depths of previous potential mud reservoirs using a isostatic eruption model. The results show that the depths of mud reservoirs may have ranged from approximately 530 to 1,800 m, with maintained temperatures exceeding 20°C under high geothermal heat flux (45–60 mW/m²). Materials from these regions are of high priority for future sample return missions, for example Tianwen-3, the Mars sample return mission of China, aiming to search for martian biosignatures. Combing geological analysis and engineering constraints, we propose a scientifically very promising landing site in Utopia Planitia for Tianwen-3 mission.