Source: Earth and Planetary Physics
China’s first planetary exploration mission, Tianwen-1, was successfully launched on 23 July 2020. It has been orbiting Mars since 10 February 2021. One aspiration of the Tianwen-1 mission is to discover missing links between Martian ion-escape processes and their role in the evolution of the Martian paleoclimate. Studies based on previous Martian missions have left several unresolved arguments about how solar activity has affected the Martian climate and water loss over billions of years.
Data from Tianwen-1 significantly increase opportunities for simultaneous observation of the solar wind and the Martian space from multiple spacecraft locations, making possible valuable data that may help resolve these open questions. Two new studies illustrate this potential.
Zhang et al.  and Fan et al.  present the first solar wind plasma observations from Tianwen-1, finding that the mission has successfully captured properties and variations of the solar wind plasma. Zhang et al.  quantitatively evaluated the blocking effect of the lander capsule based on derived solar wind plasma parameters from 16:00 UT on 21 November to 10:00 UT on 22 November 2020, embracing an SIR event. Meanwhile, Fan et al.  developed a comprehensive method, including noise reduction and calculation of plasma moments, to derive solar wind velocity and density from the Tianwen-1 observations, and picked out time intervals with reliable datasets. The derived solar wind velocity and density data were also compared with near-earth observations from OMNI datasets and with near-Mars observations from NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) mission and ESA’s Mars Express mission, allowing verification of consistency between them.
In November 2021, the Mars Ion and Neutral Particle Analyzer (MINPA) started its second long-term measurement of ions and energetic neutral atoms (ENAs) in Martian space. At the same time, MAVEN and Mars Express are continuing to monitor the Martian space environment. In the coming Martian years, joint observations from Tianwen-1, MAVEN, and Mars Express will bring more opportunities for studying the evolution of the Martian atmosphere and the evolutionary history of the Martian paleoclimate.
Citations: Zhang, A. B., Kong, L. G., Li, W. Y., Li, L., Tang, B. B., Rong, Z. J., Wei, Y., Ma, J. J., Zhang, Y. T., … and Wang, C. (2022). Tianwen-1 MINPA observations in the solar wind. Earth and Planetary Physics, 6(1), 1–9. http://doi.org/10.26464/epp2022014
Fan, K., Yan, L., Wei, Y. et al. The solar wind plasma upstream of Mars observed by Tianwen-1: Comparison with Mars Express and MAVEN. Science China Earth Sciences, 65, 759–768 (2022). https://doi.org/10.1007/s11430-021-9917-0
—Limei Yan, Science Writer
Editor’s Note: Earth and Planetary Physics is an AGU partner journal; it is co-sponsored by the Chinese Geophysical Society, the Institute of Geology and Geophysics of the Chinese Academy of Sciences, and Science Press.