Nebula Public Library

Ambient space plasma can induce electrostatic noise in a linear antenna onboard a spacecraft. The resulting quasi-thermal noise (QTN) intensity spectrum as a function of frequency depends on the plasma parameters. The phenomenon can be utilised for inferring the plasma parameters if one measures the induced noise by a sensitive radio receiver. This is called QTN spectroscopy and it has been demonstrated and validated in several space missions that the technique is able to uncover the correct plasma parameters.