Plasma Wave and Sounder (PWS) instrument with its range of 20kHz to 5MHz is designed to observe the structue of the ionosphere by using the topside sounder technique together with the features of plasma waves associated with wave particle interactions which become the origin of the microprocesse s controling the direct interaction processes of ionospheric plasma with the solar wind plasma.

Low Frequency plasma wave Analyzer (LFA) onboard the Planet-B spacecraft has been developed to m easure the Martian plasma wave. The LFA has capability to measure the wave spectrum in the band from 10 Hz to 32kHz ,and its scientific objectives are ,for example, to explore macroscopic plasma envir onment and boundaries from the solar wind to the ionosphere ,microscopic plasma phenomena induced by the interaction between the solar wind and the Martian atmosphere and the moon Phobos ,and so on.