Science and Technology Daily reporter Lu Chengkuan
As the planet in the solar system that is most similar to the earth, what exactly is under the surface of Mars ? This is a long-standing question for mankind.
Based on the low-frequency radar data of the "Zhurong" rover , Chinese scientific researchers found that under the weathered layer about 10 meters thick on the surface of the rover landing area, there are two sets of upwardly thinning sedimentary sequential sequences, which may be related to multiple periods of water activities in about 3.5 billion to 3.2 billion years; now, no evidence of liquid water is found 0-80 meters below the fire table in this area, but the possibility of salt ice is not ruled out. Related research results were published online in Nature magazine on September 26.
Source: Chinese Academy of Sciences
Detailed underground structure and material properties information of Mars are the key basis for studying the evolution of Mars geology and its habitable environment, and are an important part of Mars exploration.
On May 15, 2021, the "Zhurong" Mars rover carried by my country's first Mars exploration mission, Tianwen-1 , successfully landed in the pre-selected landing area in the southern pre-selected landing area of Utopian Plain , and started patrol and exploration work.
"The subsurface detection radar carried by the Mars rover of Zhurong can finely image the shallow underground structure of the inspection area, deepening people's understanding of key scientific issues such as the evolution of utopian plains and groundwater/ice distribution." Chen Ling, a researcher at the Institute of Geology and Geophysics, Chinese Academy of Sciences, said.
Up to now, humans have conducted four inspections on extraterrestrial celestial bodies. Among them, my country's Chang'e-3 and Chang'e-4 respectively achieved fine detection of the shallow structures on the front and back of the moon. The United States' Perseverance and my country's "Zhurong" Mars rover launched Mars patrol radar detection in 2021.
"The detection area of 'Perseverance' is the edge of the Jezero impact crater, and its actual maximum detection depth is 15 meters. The detection area of the 'Zhurong' Mars rover is the southern part of the Utopian Plain, and its actual maximum detection depth is 80 meters." Chen Ling introduced.
Based on the low-frequency radar data obtained by the "Zhurong" Mars rover patrolling the landing area for 103 days and traveling about 1,171 meters, the researchers "draw" high-precision structural layered images above 80 meters shallow surface of the landing area and analyzed the material properties information of the formation.
Source: Chinese Academy of Sciences
They found that there are two sets of upwardly thinning sedimentary sequences under the fire layer about 10 meters thick in this area. The first set of hierarchies is located about 10-30 meters underground and contains more stones, which gradually increase with depth. "Short-term flooding, long-term weathering or repeated meteorite impacts from about 1.6 billion years ago may have led to the formation of this upward thinning sedimentary sequence," Chen Ling explained.
The second set of hierarchies is located about 30-80 meters underground. It contains larger stones and is more chaotic, reflecting the older and larger-scale fire table transformation incident. "Based on the results of the predecessors' annual impact crater statistics, it is speculated that this transformation incident may have occurred 3.5 billion to 3.2 billion years ago, and is related to large-scale flooding activities in the southern part of the Utopian Plain." Chen Ling said.
"Planning and taking a group photo" (data photo). Source: National Space Administration
In addition, one of the main targets of the Mars rover surface detection radar is to detect whether groundwater/ice exists in the southern part of the Utopian Plain today. The low-frequency radar imaging results of
rule out the possibility of an aqueous layer within a depth range of 0-80 meters below the patrol path. At the same time, the thermal simulation results further show that liquid water, sulfate or carbonate brine is difficult to exist within 100 meters underground in the landing area of the "Zhurong" Mars rover. "However, the possibility of salt ice cannot be ruled out at present." Chen Ling pointed out.
She said that this is an original result obtained by Chinese scientists using the scientific data of the first Mars exploration mission in my country's "Tianwen-1", revealing the superficial fine structure and material properties of Mars today, providing observational evidence of the possible long-term existence of water activities on Mars, and providing an important basis for a deep understanding of Mars' geological evolution, environment and climate change.
Source: Science and Technology Daily
Editor: Shen Wei (internship)
Review: Zhu Li
