Shulou(Shulou.com)11/24 Report--

Thanks to CTOnews.com netizens Hua Ke high achiever, SKimmy, Hello _ rabbit clue delivery! According to the Institute of Geology and Geophysics, the "Zhu Rong" rover carried by China's Tianmen-1 Mars mission successfully landed on the southern edge of the Utopian Plain (Utopia Planitia,UP) (109.925 °E, 25.066 °N) in 2021, CTOnews.com reported on May 6. This region is located in the late Western lowland (northern lowlands) unit in the northern hemisphere of Mars and belongs to the low latitudes of Mars. By the end of winter dormancy, the Zhu Rong rover had worked for more than 350 Martian days and traveled about 2,000 kilometers, obtaining a large number of valuable scientific exploration data.

Researcher of Institute of Geology and Geophysics of Chinese Academy of Sciences, researcher of National Astronomical Observatory, Doctor of Institute of Atmospheric Physics, etc., using the navigational terrain camera, multispectral camera and Mars surface composition detector carried by Zurong, to study the micro-morphology and material composition characteristics of the sand dune surface in this area. It is found for the first time that there are some surface features on the surface of sand dunes in the landing area of "Zhurong", such as crust, crack, granulation, polygonal ridge, banded water mark and so on. Through the analysis of spectral data, it is found that the surface of sand dune is rich in hydrous sulfate, opal, hydrous iron oxide and so on.

Combining the measured data of the Zurong Mars meteorological instrument with the surface observation meteorological data of other Mars probes, after excluding the possibility of groundwater and CO2, the researchers determined that these surface features are related to frost or snowfall on the surface of saline dunes during cooling. Salt-bearing sand particles promote frost and snow to melt at low temperature to form salty liquid water. After brine drying, water-bearing minerals such as sulfate, opal and iron oxides cement sand particles to form aeolian sand aggregates and even crusts, and the crusts are further dried to form cracks. In the later stage, the frost and snow further formed liquid water activity traces such as polygonal ridges and banded water marks on the crust.

At the same time, according to the statistics of meteorite craters on the sand dunes, it is determined that the sand dunes formed about 400-1.4 million years ago. Combined with the three-phase diagram of water, it is inferred that during the period of large inclination of the Martian earth axis in the late Amazon period, the diffusion and transport of water vapor from the polar ice sheet to the equator led to multiple humid environments in the low latitudes of Mars. During the large inclination of the Martian axis, the low temperature at low latitudes contributes to frost and snow, leading to surface crusting and granulation of saline dunes, resulting in sand dunes solidifying and leaving traces of liquid water activity.

The above results promote the study of the surface observation evidence of liquid water in the low latitudes of Mars, and reveal that the modern Martian climate can have a more humid environment in the low latitudes where the surface temperature is relatively warm and suitable. This is of great significance for exploring the history of Martian climate evolution and finding a livable environment, and provides a key clue for searching for the existence of life in the future. The relevant research results are published in the journal Scientific Progress.

CTOnews.com Note:

(a) the topographic contour map of the section location in figure e

(B) MSCam camera bird view photos of banded marks on bright crusts and suspected debris of flooded soil and aeolian sand aggregates on dark sand ridges

(C) enlarged images of bright polygonal ridges and cracks

(d) photographs of annular areas and their banded boundary marks

(e) 3D image of the trough between two longitudinal dark sand ridges on the west wing of the bright dune, where the white dotted line is the position of the figure f section.

(F) the topographic profile of the white dotted line in figure e.

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