Evaluating the Dust Storm Probability in Isidis‐Elysium Planitia, a Tentative Landing Area of China's First Mars Mission (Tianwen‐1)

Abstract

AbstractChina's first Mars exploration mission (Tianwen‐1), launched on July 23, 2020 with the goal of “orbiting, landing, and roving,” and its tentative landing areas (TLAs) are Chryse Planitia (TLA 1) and Isidis‐Elysium Planitia (TLA 2). Dust storm is a typical activity on Mars; it has strong interaction with atmospheric circulation and will influence the visibility of the Martian surface. To ensure the safety and accuracy for landing, it is meaningful to analyze the probability of dust storm activity during Entry‐Descent‐Landing (EDL) season in TLAs. First, based on Mars Orbiter Camera (MOC) and Mars Color Imager (MARCI) Daily Global Maps (MDGMs) from Mars Years 24–31, we identified 882 dust storms within the 2,000 km radius monitor circle of TLA 2 (short for TLA 2‐C). Second, the average daily probability of dust storm activity (Adp_ds) in TLA 2‐C was calculated, with a range of 0% to 14.13% showing obvious seasonality and discontinuity. Third, we divided TLA 2‐C into 0.5° longitude × 0.5° latitude square grids and calculated their spatial probability of dust storm activity. The spatial probability of dust storm in TLA 2‐C ranged from 0% to 11.87% and generally reduced from north to south. Finally, according to the temporal and spatial dust storm probability in TLA 2 during EDL season, we suggested the optimal landing time of China's Tianwen‐1 mission was in Ls = 20–41° and selected five preferred landing areas with the spatial probability of dust storm <3% for this mission.