Open AccessMAVEN Observations of Periodic Low-altitude Plasma Clouds at Mars
Author(s) -
Chi Zhang,
Zhaojin Rong,
Hans Nilsson,
Lucy Klinger,
Shaosui Xu,
Yoshifumi Futaana,
Yong Wei,
Jun Zhong,
M. Fränz,
Kun Li,
Hui Zhang,
Kai Fan,
Lei Wang,
Mats Holmström,
Yasong Ge,
Jun Cui
Publication year - 2021
Publication title -
the astrophysical journal. letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.639
H-Index - 201
eISSN - 2041-8213
pISSN - 2041-8205
DOI - 10.3847/2041-8213/ac3a7d
Subject(s) - atmosphere of mars , martian , mars exploration program , solar wind , physics , ionosphere , plasma , astrobiology , atmospheric escape , polar wind , atmosphere (unit) , interplanetary magnetic field , atmospheric sciences , geophysics , meteorology , quantum mechanics
Ion escape to space through the interaction of solar wind and Mars is an important factor influencing the evolution of the Martian atmosphere. The plasma clouds (explosive bulk plasma escape), considered an important ion escaping channel, have been recently identified by spacecraft observations. However, our knowledge about Martian plasma clouds is lacking. Based on the observations of the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we study a sequence of periodic plasma clouds that occurred at low altitudes (∼600 km) on Mars. We find that the heavy ions in these clouds are energy-dispersed and have the same velocity, regardless of species. By tracing such energy-dispersed ions, we find the source of these clouds is located in a low-altitude ionosphere (∼120 km). The average tailward moving flux of ionospheric plasma carried by clouds is on the order of 10 7 cm −2 s −1 , which is one order higher than the average escaping flux for the magnetotail, suggesting explosive ion escape via clouds. Based on the characteristics of clouds, we suggest, similar to the outflow of Earth’s cusp, these clouds might be the product of heating due to solar wind precipitation along the open field lines, which were generated by magnetic reconnection between the interplanetary magnetic field and crustal fields that occurred above the source.