Spatio-temporal probability analysis and predicting of Martian dust storms based on remote sensing imagery——A case study of Tianwen-1 mission

<p indent="0mm">Dust storms, a phenomenon in which dust particles form on the surface of a planet in response to strong atmospheric motions, occur in all seasons on Mars and are one of its most important atmospheric activities. Localized dust storms can last for days, and large or even global dust storms can affect the Martian atmosphere for several months. Martian dust storm events pose a serious threat to the safety of the rover landing process and can result in dust deposited on the surface of solar panels, leading to an insufficient power supply for rovers. Accordingly, to ensure the safety of the landing process of the Mars exploration mission, a temporal and spatial probability analysis of Martian dust storm events should be carried out, and dust storm events should be predicted prior to landings. This paper reviews and summarizes prediction methods for Martian dust storms developed in China and abroad, introduces the geologic conditions of the Utopia Planitia study area and the classification rules of Martian dust storms, and reports on the following tasks, taking China’s first Mars exploration mission Tianwen-1 as an example. (1) A spatial-temporal database of dust storms in the study area of Utopia Planitia was established based on the dust storm sequence from the long time-series (MY24–MY28) Mars remote sensing images and the result was compared with the Mars Dust Activity Database to validate the correctness and the completeness of the dust storms and sequences. (2) The temporal and spatial probability of dust storms in the study area were calculated, and the dust storms at the landing time and site of the <sc>Tianwen-1 mission</sc> and during the working and dormant periods of the Zhurong rover were analyzed and evaluated. The probability of dust storms at the landing site during the landing-time of Tianwen-1 was extremely low but was significantly higher during the dormant period of the Zhurong rover. (3) In the primary and secondary landing circles of Tianwen-1, the primary dust storms were classified and the features of the dust storm sequences were extracted. An analysis of the dust storm predictions prior to the landing of the Tianwen-1 mission was then conducted. In addition, the MoRIC images two days prior to the landing date were stitched and aligned. No dust storms were detected at the Martian north pole or in Utopia Planitia; therefore, it can be inferred that there were no dust storms within the primary landing circle on May 15, 2021 (MY36, Ls=45.1°) and that the landing process of Tianwen-1 was not affected by dust storm events. In the future, the regularity of Martian dust storm activity should be extended to the landing sites of other Mars exploration missions and even to a global scale. The mechanisms and influencing factors of atmospheric activities, such as dust storms, should be studied comprehensively in conjunction with atmospheric physics and other parameters (e.g., temperature, atmospheric pressure, optical depth, and wind speed and direction) simulated and computed via gas chromatography mass spectrometry. In addition, in this paper, remote sensing, in situ, and simulation data are integrated to synthetically analyze the connection and causative mechanism between different scales of Martian weather phenomena (e.g., large-scale dust storms, mesoscale eddies, and small-scale dust devils) to obtain better atmospheric activity regularity at landing sites to improve accuracy, as well as real-time Martian dust storm event analysis and prediction.