Tianwen-1 and MAVEN Observations of the Response of Mars to an Interplanetary Coronal Mass Ejection

Abstract

Interplanetary coronal mass ejections (ICMEs) are solar transients that have significant effects on the upper atmosphere and ionosphere of Mars. The simultaneous spacecraft observations from Tianwen-1/MOMAG in solar wind and multiple instruments on board the Mars Atmosphere and Volatile Evolution (MAVEN) in the Martian upper atmosphere are used to study the response of Mars to an ICME. The ICME was observed at Mars by Tianwen-1 and MAVEN at 00:00 UT on 2021 December 10, which was earlier observed by BepiColombo upstream of Mars at 22:32 UT on 2021 December 6. During 2021 December 6–15, MAVEN measured the nightside ionosphere and Tianwen-1 measured the dayside ionosphere while both were inside the Martian bow shock. The rapid drop in densities of ionospheric ions and electrons, which is typically identified as the end of the ionosphere at altitudes between 300–800 km, is known as the ionopause. The altitude of the Martian ionopause location was lowered by the high dynamic pressure of the solar wind during the ICME passage. The depletion of the plasma density in the topside Martian ionosphere on the nightside reveals the presence of substantial ion and electron escape to space through the interaction between the ICME and Mars. The column abundance of plasma dramatically decreased, with 34% e−, 61% O 2 + , and 73% O+ reduced. This study highlights the significant impact of the space weather associated with the intense magnetic field and high dynamic pressure of the ICME on Mars’s atmosphere, which is particularly important for future human exploration missions to Mars.

Prediction for Arrival Time and Parameters of Corotation Interaction Regions using Earth–Mars Correlated Events from Tianwen-1, MAVEN, and Wind Observations

“…The deformation of the IMF structure outside of the Parker spiral causes the deviation of the prediction. Moreover, the prediction results that the arrival time of CIR-1 is earlier than expected at BepiColombo but later than expected at Mars also indicate that the rotation of the CIRs is not constant (Allen et al 2020) Previous studies have identified CME events that occurred during the study period (e.g., Chi et al 2023aChi et al , 2023bYu et al 2023). These CMEs may have cleared some of the ambient solar wind plasma (Chi et al 2020), leading to a rarefied and disturbed solar wind; consequently, the prediction for the in situ parameters of CIRs is affected.…”