Scientists have discovered the existence of high-frequency plasma waves in the upper atmosphere of Mars with amazing narrowband and broadband characteristics that may help understand plasma processes in the Martian plasma environment.
Various plasma waves are often observed in the Earth's magnetosphere, a magnetic field cavity around the Earth. In general, plasma waves are detected as short time scale fluctuations in electric and magnetic field observations. These plasma waves play an important role in energizing and carrying charged particles in the Earth's magnetosphere. Some plasma waves such as electromagnetic ion cyclotron waves act as scavenging agents for Earth's radiation belts, which is dangerous for our satellites. Knowing this scenario, researchers are eager to understand the existence of different plasma waves around unmagnetized planets like Mars. Mars has no internal magnetic field so the high-speed solar wind coming from the Sun interacts directly with the Martian atmosphere, like an obstacle to the flow.
Researchers at the Indian Institute of Geomagnetism (IIG), an autonomous institute of the Department of Science and Technology, have observed high-frequency plasma waves in the Martian plasma atmosphere using high-resolution electric field data from the Martian atmosphere and NASA's Volatile Evolution. Mission (MAVEN) spacecraft ( https://pds-ppi.igpp.ucla.edu ). These waves can either be electron pulses that propagate parallel to the background magnetic field (Langmuir waves) or electron pulses that propagate perpendicular to the background magnetic field (upper-hybrid type waves) in the magnetosheath region of Mars.
They observed two distinct wave modes in the magnetosphere of Mars with a frequency below and above the electron plasma frequency. These waves were observed around 5 LT (local time) on February 9 , 2015 , when the MAVEN spacecraft crossed the magnetopause boundary and entered the magnetosheath region. These waves are either broadband- or narrowband-type with distinct characteristics in the frequency domain. Periodic patchwork structures with a periodicity of 8–14 milliseconds were consistently found in broadband waves.
Observation of such waves provides a tool to explore how electrons gain or lose energy in the Martian plasma environment. The physical mechanisms responsible for the production of broadband-type waves and its modulation remain unclear and require further investigation. This study was conducted by IIG scientists in collaboration with scientists from Japan, USA and UAE and has been published in the Astronomy and Astrophysics Journal.
