Recently, members of the "Sun Burst and Its Impact on the Planetary Space Environment" Climbing Group of Shandong University, the Planetary Science Group of the Institute of Space Science, published in the "Earth and Space Science" a research paper on the probability of Martian dust storm occurred in the pre-selected landing area of China's first Mars exploration mission "Tianwen-1". The first author of the paper is Peiwen Yao, a master's student of the Planetary Science Group, and the corresponding author is Associate Professor Bo Li. The title of the paper is: "Evaluating the dust storm probability in Isidis-Elysium Planitia, a tentative landing area of China's first Mars mission (Tianwen-1)" (Yao et al., 2020, Earth and Space Science, DOI: 10.1029/2020EA001242). Link: https://doi.org/10.1029/2020EA001242
Dust storm on the surface of Mars occur in all seasons of Mars and is a typical activity on Mars. Limited to engineering technology and scientific level, early landing probes did not consider the terrain and other related factors, so the landing success rate was meager. A global dust storm swallowed the first lander "Mars-2" at the beginning of its landing, and a dust storm also destroyed " Mars-3", and its communication system was destroyed. In 2004, NASA's "Spirit" and "Opportunity" landed in the southern hemisphere during the summer and encountered dust storms that were larger than expected. The landing locations were 10.1 and 24.6 kilometers away from the pre-selected landing ellipse center, respectively. Besides, dust storms reduce visibility and bring a large amount of dust deposited on the solar panels, causing the rover to stop working due to insufficient power. Therefore, the ability to analyze the temporal and spatial distribution of dust storms in the Mars pre-selected landing zone is one of the critical technologies that need to be studied in advance and is challenging in the Mars exploration mission. It is related to the landing mission's success and affects the landing accuracy and the regular operation of the probe.
At 12:41 on July 23th, 2020, the Long March 5 carrier rocket successfully launched China's first Mars exploration mission, "Tianwen-1," at the Wenchang Space Launch Site in Hainan, starting a journey to explore Mars and stepping forward, the first step in China's autonomous planetary exploration. "Tianwen-1" consists of three parts: the orbiter, the lander, and the rover. The goal is "orbiting, landing, and roving." Isidis‐Elysium Planitia is one of the tentative landing areas (figure 1.), are the preferred regions for the northern dust storm. The impact of Martian dust storm events on the Martian landing area cannot be ignored. Therefore, exploring the temporal and spatial probability of the Martian dust storm in the Isidis-Elysium Planitia and its surrounding areas is very important for the successful realization of the "Tianwen-1" mission.
This study calculates and analyzes the temporal and spatial probability of dust storm activity in and around Isidis-Elysium Planitia. We identified 882 dust storms within the 2,000 km radius monitor circle of Isidis-Elysium Planitia based on MOC and MARCI Daily Global Maps (MDGs) from Mars Years 24–31. Integrating the frequency of dust storms, the weighted average of the percentage of coverage area, and the probability of repeated occurrences of dust storms, a method for calculating the space-time probability of dust storms is proposed. The space-time probability of dust storms in the study area is calculated. Adp_ds of TLA 2 and TLA 2‐C showed apparent inhomogeneity and seasonality within a Martian year. The probability of dust storms in the northern autumn and winter is significantly higher than that in northern spring and summer, the two active periods of dust storm activity in the study area are Ls=176°-225° and Ls=302°-355° (Figure 2). Finally, the dust storm time and space safety of the Isidis-Elysium pre-selected landing area are evaluated and analyzed. Based on the dust storm space-time probability, a suitable landing time (Ls=20°-41°) and five safer landing areas.
This work is supported by the Strategic Leading Science and Technology Special Project of Chinese Academy of Sciences, the Shandong Provincial Natural Science Foundation, the Preresearch project on Civil Aerospace Technologies funded by China National Space Administration (CNSA), the National Natural Science Foundation, and the Program for JLU Science and Technology Innovative Research Team. Shandong University has been building the direction of planetary science since 2006 and has a solid research foundation in Mars scientific research. From Martian sulfate analog study to Martian meteorites, Martian remote sensing, Martian atmosphere, and surface environment analog, the pace of scientific study on Mars at Shandong University has never stopped. So far, the planetary science group of Shandong University has received support from the civil aerospace projects related to Mars research, the key project of the National Natural Science Foundation of China's Astronomy Joint Fund, and the Shandong Natural Science Foundation. It has published 20 related papers in EPSL, JGR, Icarus, and other magazines. Moreover, a laser-induced breakdown spectroscopy system was successfully built to assist the scientific interpretation of future Mars exploration data. Relevant teachers of the Institute of Space Science of Shandong University have been selected as the "First Mars Exploration Mission Scientific Target Preliminary Research Team" organized by the Lunar Exploration and Space Engineering Center, and are preparing for the research and analysis of the scientific data returned by the "Tianwen-1".
Figure 1. The pre-selected landing area of "Tianwen-1".
Figure 2. Time probability of Isidis-Elysium dust storm.
Figure 3. Spatial probability of Isidis-Elysium dust storm and choice of safe landing area.