The discovery of liquid water on Mars is significant for interstellar migration and the study of Martian climate evolution. Chinese researchers have found evidence of liquid water on Mars, formed from frost or snowfall, using data collected by their Mars rover Zhurong.
The research, published in Advances in Science and Research, identified crusted surfaces, cracks, granulation, polygonal ridges and band-shaped water marks on Martian sand dunes within the landing area of the Zhurong rover. Analysis suggests that these dune surfaces are rich in water-containing minerals such as hydrous sulfates, protein stones and hydrous iron oxides.
Liquid water is essential for creating a habitable environment and supporting life on Mars. While previous studies have shown that there was once a significant amount of liquid water on early Mars, changes in its climate and environment occurred with the dissipation of its early atmosphere. Due to the extremely low air pressure and water vapor content, it is challenging for liquid water to exist stably on present-day Mars, limiting it to solid or gaseous forms.
However, droplets observed on the mechanical arm of the US Phoenix Mars probe suggest that saltwater may appear during summer at high latitudes on current-day Mars. Numerical simulations also indicate that suitable climatic conditions for liquid water may briefly occur in certain areas of present-day Mars. Nonetheless, direct observational evidence is still lacking regarding whether liquid water exists in low-latitude regions where temperatures are highest.
In 2021, China’s first Mars exploration mission Tianwen-1 successfully landed the Zhurong rover on the southern edge of Utopia Planitia, a low-latitude region on Mars.
Researchers used data from the rover’s weather station and meteorological data from other Mars probes to determine that the water-containing features in the sand dunes are related to frost or snowfall during cooling.
These accomplishments advance the investigation of ground observations indicating the presence of liquid water in Mars’ low latitudes. They demonstrate that a wetter environment can exist in areas with relatively warm and suitable surface temperatures, highlighting the potential for exploring Mars’ climate evolution history and discovering habitable environments.