On May 15, 2021, the "Zhurong" Mars rover carried by Tianwen-1, China's first Mars exploration mission, successfully landed in the pre-selected landing area in the southern Utopia Plain, starting the inspection and exploration work. Chinese scientists recently used the scientific data obtained by the "Tianwen-1" Mars exploration mission to reveal the superficial fine structure and physical characteristics of Mars today, providing an important basis for an in-depth understanding of the geological evolution, environment, and climate change of Mars.
The "Zhurong" rover's detection area is the southern part of the Utopia Plain, with a wide radar band, and its actual maximum detection depth is 80 meters. The Utopian Plain, the largest impact basin on Mars, may have once been an ancient ocean, indicating that Mars may have had a habitable environment in the early days. Detailed information on the subsurface structure and physical properties of Mars is the key basis for the study of Martian geology and the evolution of its habitable environment and is an important part of Mars exploration.
In the latest study, the researchers conducted an in-depth analysis of the low-frequency radar data of the "Zhurong" rover with a detection length of 1,171 meters in the first 113 Martian days and obtained high-precision structural layered images above the superficial 80 meters. and stratigraphic physical property information, it is found that there are two sets of upward thinning sequences under the several-meter-thick fire soil layer in this area, which may reflect the multi-stage fire surface transformation process related to water activity from about 3.5 billion to 3.2 billion years.
In addition, one of the main objectives of the "Zhurong" Mars rover's subsurface detection radar is to detect the presence of groundwater/ice in the southern part of the Utopia Plain. The low-frequency radar imaging results show that the reflected signal intensity is stable in the depth range of 0-80 meters, and the medium has a low dielectric constant, which excludes the possibility of a water-rich layer under the patrol path. The thermal simulation results further show that it is difficult for liquid water, sulfate, or carbonate brine to exist stably within 100 meters of the landing area of ​​the "Zhurong" rover, but the possibility of salt ice cannot be ruled out at present.
The relevant research results were published in the international academic journal "Nature" on the evening of September 26.