Can liquid water be found in the southern part of the utopian plains of Mars now? The Institute of Geology and Geophysics, Chinese Academy of Sciences, together with the National Space Science Center of the Chinese Academy of Sciences and Peking University, through analysis of the radar data of the "Zhurong" Mars rover patrol, found that Mars may have water activity for a long time. There is no evidence that liquid water still exists today, but the possibility of salt ice is not ruled out. The results of the research related to were published in the international academic journal "Nature" on the evening of September 26, Beijing time.
[The world's first patrol radar detection in the Utopian Plain]
On May 15, 2021, my country's first Mars exploration mission, "Tianwen-1", carried the "Zhurong" Mars rover and successfully landed in the pre-selected landing area in the southern Utopian Plain. The Utopian Plain is the largest impact basin on Mars. Previous studies have found that the climate here was once warm and humid, indicating that there may have been a livable environment in the early days of Mars.
From warm and humid to cold and dry, how does the geology of Mars evolve? Is water or ice still present today? This is an important issue that "Tianwen-1" Mars exploration wants to explore. The subsurface detection radar carried by the "Zhurong" Mars rover is the first patrol radar detector implemented in the utopian plain in . can finely image the shallow underground structure of the inspection area. So far, humans have conducted four inspection radar detections 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 in the southern part of the Utopian Plain, with a wide radar frequency band and an actual maximum detection depth of 80 meters.
[Fire meters transformation related to water activities may occur many times]
is different from the moon. The landing area of the "Zhurong" Mars rover is distributed with concave cones, barrier craters, trenches, etc. These landforms indicate that there may be important connections with water activities.
In this latest study, scientific researcher provides observational evidence of the possible long-term existence of water activity on Mars. They conducted in-depth analysis of the low-frequency radar data of the "Zhurong" Mars rover with a detection length of 1171 meters in the first 113 Mars days, and obtained high-precision structural layered images and stratigraphic properties information above 80 meters shallow.
detection length up to 1171 meters
Research found that there are two upwardly thinning sedimentary sequences under the several meters of ignition layer in this area, which may reflect that fire meter transformations related to water activities have occurred many times over the past 3.5 billion to 3.2 billion years. The first set of hierarchies is located about 10-30 meters underground and contains more stones. The particle size gradually increases with depth. This may be caused by the short-term flooding of , long-term weathering or repeated meteorite impacts of in about 1.6 billion years; the second set of hierarchies is located about 30-80 meters underground, and the stone particle size is larger, reaching the meter level, and the distribution is more chaotic, which reflects an older and larger-scale fire table transformation event. Based on the results of the previous generation's 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 floods in the southern part of the Utopian Plain.
[At a depth of 0 to 80 meters, there is no liquid water detectable by radars now]
Since Mars may have water activity for a long time, is there still water in this area now? The low-frequency radar imaging results of "Zhurong" show that the reflected signal intensity within the depth range of 0-80 meters below the firemeter is stable, and the medium has a low dielectric constant (no more than 9), which ruled out the possibility of an aqueous layer below the patrol path.
" If liquid water is present, the dielectric constant must reach at least 15, and the radar signal will also attenuate, making it difficult to see strong reflections at a depth of 70 or 80 meters. In addition, we also calculated the annual average temperature of 1-100 meters underground in the inspection area, which is about 220k, which is far lower than the freezing point of water, and the eutectic temperature of brine containing sulfates, carbonates and other brines." Chen Ling , a researcher at the Institute of Geology and Geophysics, Chinese Academy of Sciences, said that these evidences show that in the depth range of 0 to 80 meters, there is no liquid water detectable by radars now, but the possibility of salt ice cannot be ruled out at present.
This research is an original result obtained by Chinese scientists using the scientific data of the first Mars exploration mission in my country's "Tianwen-1", and provides an important basis for a deep understanding of Mars geological evolution, environment and climate change.
title image source: Xinhua News Agency Image editor: Shao Jing
Source: Author: Huang Haihua
