Instrument to measure lightning on Mars
doi:10.1038/nindia.2019.32 Published online 14 March 2019
Astrophysicists have gained new insights into the phenomena that occur along with lightning on Mars1.
They have detected that lightning generates extremely low-frequency electromagnetic waves, a finding that could shed light on the global circuit, interaction between aerosol and dust clouds, and their subsequent effects on the climate of the red planet.
Lightning on Mars produces extremely low-frequency electromagnetic waves that are known as Schumann Resonance (SR) frequencies. Such frequencies form between the Martian surface and the ionosphere. On Earth, previous studies had shown that SR frequencies might be constant. Being sensitive to conductivity, which changes with altitude, SR frequencies could change with altitude.
To figure out the relationship between the conductivity, lightning and SR frequencies, scientists from the Physical Research Laboratory in Ahmedabad, Gujarat, and Pacific University in Udaipur, Rajasthan, both in India, calculated the electrical conductivity and SR frequencies in the lower ionosphere of Mars in the presence of a major dust storm at a low-latitude region.
They found that the atmospheric conductivity dropped by one to two orders of magnitude in the presence of a dust storm during the night. It happens in a small dust layer lying between 25 km and 30 km of where lightning can occur.
Results indicate that measurable values of SR are dependent on the altitude. Besides, SR frequencies are one of the lightning-produced natural signals. Such frequencies can be used to measure lightning on Mars from a spacecraft.
Armed with this knowledge, the researchers are developing an instrument, called the Lightning Experiment for MArs (LEMA), that can capture Martian lightning during a future Indian Mars mission.
1. Haider, S. A. et al. Schumann resonance frequency and conductivity in the nighttime ionosphere of Mars: a source for lightning. Adv. Space. Res. 63, 2260-2266 (2019)