Researchers have identified the presence of high-frequency plasma waves in the upper atmosphere of Mars, showcasing unique narrowband and broadband characteristics that offer insights into plasma processes within the Martian plasma environment.
Plasma waves, commonly observed in Earth’s magnetosphere, represent short-term fluctuations in electric and magnetic field observations. These waves play a crucial role in the energization and transportation of charged particles within Earth’s magnetosphere. Certain plasma waves, such as electromagnetic ion cyclotron waves, even serve as a cleansing mechanism for Earth’s radiation belt, which poses a threat to satellites. Given this understanding, scientists are eager to explore the existence of various plasma waves around unmagnetized planets like Mars. Mars lacks an intrinsic magnetic field, exposing its atmosphere directly to the high-speed solar wind from the Sun, acting as an obstacle in its flow.
Researchers from the Indian Institute of Geomagnetism (IIG), an autonomous institute of the Department of Science and Technology, investigated the presence of high-frequency plasma waves in the Martian plasma environment. They utilized high-resolution electric field data from NASA’s Mars Atmosphere and Volatile Evolution Mission (MAVEN) spacecraft. These waves may manifest as electron oscillations either parallel (Langmuir waves) or perpendicular (upper-hybrid type waves) to the background magnetic field in the magnetosheath region of Mars.
During the observation on February 9, 2015, around 5 LT (local time), when the MAVEN spacecraft crossed the magnetopause boundary and entered the magnetosheath region, two distinct wave modes were identified with frequencies below and above the electron plasma frequency in the Martian magnetosphere. These waves, whether broadband or narrowband, exhibited noticeable features in the frequency domain. Broadband waves consistently displayed periodic patchy structures with a periodicity ranging from 8 to 14 milliseconds.
The findings offer a valuable tool to investigate how electrons gain or dissipate energy in the Martian plasma environment. However, the physical mechanism responsible for generating broadband-type waves and their modulation remains unexplained, necessitating further investigation. The study, conducted by IIG scientists in collaboration with researchers from Japan, the USA, and the UAE, has been published in the Astronomy & Astrophysics Journal.