Abstract
China’s first Mars exploration mission (Tianwen-1) landed on the southern part of Mars’ Utopia Planitia on 15 May 2021. The Zhurong rover will focus on high-resolution and in situ observations of key areas on the surface of Mars. Dust devils (DDs) are heat-driven vortices that lift material from the surface and inject it into the atmosphere. The dark or bright surface lineaments left by DDs are called dust devil tracks (DDTs). Dust devils can clear dust from solar panels deposited by gusts and dust storms. Therefore, it is of importance to study the encounter rates of dust devils at the Tianwen-1 landing site for achieving the rover’s long-term scientific goals. Based on High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) images, 248 newly formed DDTs in 12 image pairs were firstly identified, and their lengths, widths, and direction in the study area were measured. The distribution of their width frequency follows a −2 differential power law. Secondly, DDT formation rates were computed and analyzed with the range of 0.00006 to 0.1275 ddt km−2 sol−1, mainly affected by factors such as seasons and dust storm occurrence. Thirdly, the solar panel clearing recurrence interval derived from the orbital data in our study area was calculated from ~980 to 166,700 sols. The dust storm occurrence probability at the Tianwen-1 landing area is less than 3%, and there is a special anti-dust coating on board the Zhurong rover. Thus, the Zhurong rover can be considered competent for scientific exploration.
Highlights
Dust devils (DDs), common on Earth and Mars, are special rotating convective motions due to uneven local heating [1]
CTX and High Resolution Imaging Science Experiment (HiRISE) images, we focused on the following work in the study area: (1) identidust and measuring their their lengths, widths, and and orientations; (2) calculating fyingdevil dusttracks devil tracks and measuring lengths, widths, orientations; (2) calculatDDT
The persistent period of Dust devil tracks (DDTs) is about tens or hundreds of sols due to the fact that DDTs can be erased by dust deposition in dust storm events [26]
Summary
Dust devils (DDs), common on Earth and Mars, are special rotating convective motions due to uneven local heating [1]. Several studies analyzed dust devil tracks on Mars to determine the seasonal changes of DDs and to reflect the geological background of the landing areas. Through more than 3000 Mars Orbiter Camera (MOC) narrow-angle (NA) images with a resolution of 7 m pixel−1 , Balme et al (2003) investigated a large number of DDTs in two large research areas, namely, Argyre Planitia and the Hellas Basin [17] They used the measurement of DDTs’ density to infer the influence of seasons and surface physical properties on the formation of DDTs. They used the measurement of DDTs’ density to infer the influence of seasons and surface physical properties on the formation of DDTs In both regions, DDTs’ density varied with the seasons, and active dust devils occurred mainly in spring and summer. Five-pointed star represents the landing site of Tianwen-1
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