The solar wind plasma upstream of Mars observed by Tianwen-1: Comparison with Mars Express and MAVEN

Abstract

On the great journey to Mars, China’s first planetary exploration mission, the Tianwen-1 came within 26 million kilometers of Mars from 31 October 2020 to 25 January 2021 and was getting closer to its destination, the red planet, in search of answers to the cataclysmic climate change that occurred in Martian history. Both the escape of the Martian atmosphere and the loss of surface water were firmly influenced by solar activities. Tianwen-1 provided a unique chance to depict the solar wind streams between Earth and Mars during the minimum of Solar Cycle 25. During the three-month cruise phase of Tianwen-1, the solar wind flows were successively observed at Earth, Tianwen-1, and Mars. After the field of view correction and noise reduction, the solar wind velocity and density measured by Tianwen-1 show good agreement with those at Earth and Mars. The results indicate that the performance of the ion analyzer onboard the Tianwen-1 orbiter is reliable and stable. It is worth looking forward to the joint observations of ion escape with other Mars probes in the following Martian years.