Research advances in China’s Tianwen-1 Mars mission

China’s first Mars exploration mission, Tianwen-1, was launched on 23 July 2020 and achieved orbiting on 10 February 2021, landing on 15 May 2021, and roving on 22 May 2021. Here we outline the major research progress made during the Tianwen-1 mission, drawing insights from both the Zhurong rover and the orbiter. The Zhurong rover has performed in-situ characterization of the geomorphological features, surface and subsurface geology, magnetic field, and chemical compositions along its ~1.9-km traverse to the south in southern Utopia Planitia, Mars. Measurements demonstrated a stratigraphic sequence involving initial barchan dune formation, indicative of north-easterly winds, cementation of dune sediments, followed by their erosion by north-westerly winds, eroding the barchan dunes and producing distinctive longitudinal dunes, with the transition in wind regime consistent with the end of the ice age. Surface features, i.e., crusts, cracks, aggregates, and bright polygonal ridges of hydrated salt-rich dunes likely indicate the involvement of recent saline water from thawed frost or snow. A multi-layered structure with a thickness of ~70 m has been imaged by the ground-penetrating radar onboard the Zhurong rover below a <10-m-thick regolith, and interpreted to reflect the occurrence of episodic hydraulic flooding sedimentation during the Late Hesperian to Amazonian. The lateral frequency-variation patterns of radar reflections below ~30 m depth are further interpreted as buried polygonal terrain possibly generated by freeze-thaw cycles in an epoch of strong palaeoclimatic variability at low-to-mid latitudes. The first-time multiple-points ground magnetic vector measurements were conducted, revealing an extremely weak and probably long-lasting magnetic field of ~10 nT. In addition, cameras onboard the Tianwen-1 orbiter facilitate generating a global color image of Mars and unveiling the seasonal variation of the Martian south polar cap. Along with other solar energetic particle analyzers, the Tianwen-1 orbital data were used to reconstruct the energy spectrum of space radiation at Mars.