One year after the landing of Tianwen! Did Zhurong discover water on Mars? It has something to do with manned Mars exploration

On May 15, 2021, the Tianwen-1 probe successfully landed in the pre-selected landing area, and my country's first Mars exploration mission landed on Mars successfully. my country is also the only country in the world that currently has both lunar and Mars rovers in service.

my country's first Mars exploration mission, the Tianwen-1 probe (including the Zhurong Mars rover, entry capsule, orbiter, etc.) and the Long March 5 carrier rocket used for its launch were developed by the China Aerospace Science and Technology Corporation, and other subsystems of the project also involved relevant units of the China Aerospace Science and Technology Corporation.

Tianwen-1 probe "landing photo"

As the Tianwen-1 probe is about to celebrate the first anniversary of its landing on Mars, my country's scientific research team released the latest research results based on the Zhurong exploration data: the "Zhurong" landing area (as well as a wide area of ​​the northern plains of Mars) may contain a large amount of usable water in the form of hydrous minerals, which can be used as in-situ resources for future manned Mars exploration.

(A) Topographic map of the landing site of Zhurong; (B) Map of the patrol route of Zhurong (Liu et al., 2022, Science Advances)

Using the short-wave infrared spectrum and navigation and terrain camera data obtained by the Zhurong Mars rover, a research team from the State Key Laboratory of Space Weather at the National Space Science Center of the Chinese Academy of Sciences discovered a rockized plate-like hard crust layer in the landing area of ​​the Zhurong Mars rover. Analysis showed that it is rich in minerals such as hydrated sulfates, marking the first time in the world that Zhurong has achieved the detection of hydrated minerals in situ on Mars using the short-wave infrared spectrometer on a rover.

Panoramic views of the navigation camera (A) sol 32, (B) sol 43, and (C) sol 45. White arrows indicate the location of the target rock for SWIR spectroscopy observation. (D) Zoomed-in image of the spectrally measured rock. (E) Comparison of SWIR spectra with laboratory spectra. The top figure shows the smoothed SWIR spectrum (thick solid line) superimposed on the original spectrum (thin solid line) (Liu et al., 2022, Science Advances)

The landing area of ​​the Zhurong rover is located in the young Amazonian strata that have undergone a remodeling event. Existing studies have shown that the climate on Mars was cold and dry during the Amazonian period, and the scope and extent of liquid water activities were extremely limited. The Zhurong rover found signs of water activity in the geologically young landing area, indicating that the Martian hydrosphere during the Amazonian period may have been more active than previously thought. This discovery is of great significance for understanding the evolutionary history of the climate and environment on Mars.

Schematic diagram of the formation process of sulfate-rich lithified crust in the Zhurong landing area. Stage 1: Evaporation occurs near the groundwater level and in the capillary margin zone, where salt cements are precipitated. The pre-sedimentary weathering layer forms a thin crust layer through cementation and lithification. Stage 2: Groundwater level fluctuations thicken the crust layer. Stage 3: Loose sediments are eroded to expose the erosion-resistant crust layer. (Liu et al., 2022, Science Advances) As of May 5, 2022, the Tianwen-1 probe orbiter has been in orbit for 651 days, 240 million kilometers from the Earth, and the Zhurong rover has worked on the Martian surface for 347 Martian days, traveled a total of 1,921 meters, and the two devices have accumulated about 940GB of original scientific data and are operating normally.

During the orbit around Mars, all seven payloads carried by the Tianwen-1 probe's orbiter were powered on to continue global remote sensing detection of Mars.

On April 17, 2022, an image of the Triolet crater on Mars was taken by the high-resolution camera of the Tianwen-1 probe orbiter with a resolution of about 0.8 meters per pixel, showing the "seasonal slope patterns" on the crater wall.

On April 1, 2022, the local topography of the Mariner Valley on Mars was taken by the medium-resolution camera of the Tianwen-1 probe orbiter, with a resolution of about 65 meters/pixel.

After completing its scheduled 90-Mars-day patrol and exploration mission on August 15, 2021, the Zhurong Mars rover continued to carry out expanded patrol and exploration missions.

An image of rocks distributed near an impact crater on the surface of Mars taken by the Zhurong rover's navigation and terrain camera on April 10, 2022 (the 323rd Martian day after landing).

Currently, the area where the Zhurong Mars rover is located has entered winter. Similar to our Earth, after entering winter, the solar illumination altitude angle in the northern hemisphere decreases and the illumination duration shortens. According to measurements, the local maximum temperature at noon on the Mars rover has dropped to -20°C, and the ambient temperature at night is as low as -100°C. In addition, due to the presence of sandstorms, the light intensity is further weakened, affecting the power generation capacity of the Mars rover's solar wing battery array. Recently, the engineering team has adopted the method of rotating the solar wing to adjust the illumination angle, reduce the daily work items and duration, and achieve energy balance.

Mars' rotation period is close to that of the Earth, with a Martian day only about 40 minutes longer than that of the Earth. The inclination of the rotation axis of Mars is 25.19°, which is also very close to that of the Earth. Therefore, Mars also has day and night alternations and four seasons like the Earth. The orbital period of Mars is about 687 days, that is, one Martian year is equivalent to 1.9 Earth years, which means that the average duration of each season on Mars is about twice that of the Earth.

When Zhurong first landed last year, Mars was near its aphelion, and the sun was directly above the northern hemisphere. At that time, the northern hemisphere where Zhurong was located had just entered summer, and the southern hemisphere had entered winter. Now, nearly a year after landing on Mars, Mars is near its perihelion, and the sun is directly above the southern hemisphere. The northern hemisphere where Zhurong is located is entering winter, and the southern hemisphere is entering summer.

In the next two months, the sun's direct point will continue to move toward the southern part of Mars, and will reach the Tropic of Capricorn in mid-to-late July, when the northern hemisphere of Mars will enter the coldest season of the year. In order to safely survive the cold winter and sandstorms on Mars, the Zhurong Mars rover has designed autonomous sleep and other working modes. When the energy is reduced to a certain level, it will automatically enter the sleep mode, and resume normal working mode when the environmental conditions gradually improve.