In a groundbreaking discovery, the Zhurong rover – part of China’s Tianwen-1 Mars mission – has found evidence of liquid water on the Red Planet. Until now, it was widely believed that water could only exist on Mars in its solid or gaseous states. However, the rover has discovered evidence of liquid water at low Martian latitudes, indicating potentially habitable environments. This incredible discovery was made by analysing morphological features and mineral compositions of dunes in the landing area.
Researchers from the Institute of Geology and Geophysics (IGG) of the Chinese Academy of Sciences (CAS) led the study, which was published in the journal Science Advances. The National Astronomical Observatories of CAS and the Institute of Atmospheric Physics of CAS were also involved in the study. The discovery of liquid water on the dune surfaces of modern Mars was made using data obtained by the Navigation and Terrain Camera (NaTeCam), the Multispectral Camera (MSCam), and the Mars Surface Composition Detector (MarSCoDe) aboard the Zhurong rover.
The analysis of spectral data revealed that the dune surficial layer is rich in hydrated sulfates, hydrated silica (especially opal-CT), trivalent iron oxide minerals (especially ferrihydrite), and possibly chlorides. The researchers discovered important morphological features on the dune surfaces, such as crusts, cracks, granulation, polygonal ridges, and a strip-like trace. “According to the measured meteorological data by Zhurong and other Mars rovers, we inferred that these dune surface characteristics were related to the involvement of liquid saline water formed by the subsequent melting of frost/snow falling on the salt-containing dune surfaces when cooling occurs,” said Prof. Qin from the IGGCAS.
The estimated age of the dunes is about 0.4-1.4 million years old, and the relationship among the three phases of water suggests that the transfer of water vapour from the polar ice sheet towards the equator during Mars’s late Amazonian period led to repeated humid environments at low latitudes. Therefore, a scenario of water activity has been proposed, i.e., cooling at low latitudes during the large obliquity stages of Mars’s late Amazonian period prompts frost/snow to fall and subsequently results in the formation of crusts and aggregates on the salty dune surface, solidifying the dunes and leaving traces of liquid saline water activity.
“This is important for understanding the evolutionary history of the Martian climate, looking for a habitable environment, and providing key clues for the future search for life,” said Prof. Qin. This incredible discovery provides key observational evidence of liquid water at Martian low latitudes, where surface temperatures are relatively warmer and more suitable for life than at high latitudes. The discovery is not only important for scientists curious about the history and habitability of our neighbouring planet, but it also provides a vital clue for future missions searching for life beyond Earth.