Visual Localization of the Tianwen-1 Lander Using Orbital, Descent and Rover Images

Abstract

Tianwen-1, China’s first Mars exploration mission, was successfully landed in the southern part of Utopia Planitia on 15 May 2021 (UTC+8). Timely and accurately determining the landing location is critical for the subsequent mission operations. For timely localization, the remote landmarks, selected from the panorama generated by the earliest received Navigation and Terrain Cameras (NaTeCam) images, were matched with the Digital Orthophoto Map (DOM) generated by high resolution imaging camera (HiRIC) images to obtain the initial result based on the triangulation method. Then, the initial localization result was refined by the descent images received later and the NaTeCam DOM. Finally, the lander location was determined to be (25.066°N, 109.925°E). Verified by the new orbital image with the lander and Zhurong rover visible, the localization accuracy was within a pixel of the HiRIC DOM.

Layered Ejecta Craters in the Candidate Landing Areas of China's First Mars Mission (Tianwen‐1): Implications for Subsurface Volatile Concentrations

“…Wu, Dong, et al, 2021): the southern Utopia-Isidis Planitia (SUIP) and southern Chryse Planitia (SCP; Figure 2). Although the Tianwen-1 mission landed in Utopia Planitia at 109.925°E, 25.066°N (e.g., Liu et al, 2021;Mills et al, 2021;Wan et al, 2021;X. Wu, Liu, et al, 2021;Zhao et al, 2021), our analysis included both candidate areas as mentioned above for full documentation and comparison purposes.…”

“…Given the rover's requirement for touchdown safety and mobility, two candidate landing areas were selected for the Mars exploration mission in the latitude range of 5–30°N (Ye et al., 2017; B. Wu, Dong, et al., 2021): the southern Utopia‐Isidis Planitia (SUIP) and southern Chryse Planitia (SCP; Figure 2). Although the Tianwen‐1 mission landed in Utopia Planitia at 109.925°E, 25.066°N (e.g., Liu et al., 2021; Mills et al., 2021; Wan et al., 2021; X. Wu, Liu, et al., 2021; Zhao et al., 2021), our analysis included both candidate areas as mentioned above for full documentation and comparison purposes. In general, the scientific objectives of the mission are to conduct field geological mapping, investigate the surface soil characteristics and material composition, detect water‐ice distribution, and explore the atmospheric ionosphere and surface climate and environment conditions.…”

Initial results of the meteorological data from the first 325 sols of the Tianwen-1 mission

“…Additionally, the orbiter provides a relay communication link to the rover, while performing its own scientific observations. After about three-month circling around Mars at a parking orbit, the rover, known as Zhurong, was released in May 2021 touching down on Utopia Planitia, close to the boundary between Martian northern lowlands and southern highlands, de facto in the northern lowlands of Mars (109.925° E, 25.066° N) 12 . Choosing the landing site is a strong guarantee for follow-up work (“Methods”).…”

Pan-location mapping and localization for the in-situ science exploration of Zhurong Mars rover

“…On May 15, 2021, the Tianwen-1 probe successfully landed in Utopia Planitia, which lies in the northern hemisphere of Mars [1,2]. The safe landing of Tianwen-1 marks a milestone of China's first Mars exploration mission.…”