An ionospheric sounder for the Mars landers
Résumé
The planet Mars has been visited in the past by orbital probes and landers to study the atmosphere and the ground. But despite these numerous missions, more than 20 years ago, many parameters and phenomena are not known at this time. The large possibilities given by new technologies, in terms of weight and power consumption, allow the realization of new experiments at the surface of Mars. The aim is to propose the installation of a bottomside ionospheric sounder. This instrument will contribute to our scientific understanding of Mars. It will answer one of the main scientific objectives of the IMEWG (International Mars Exploration Working Group) mission scenario: the characterization of the Martian upper atmosphere and its interaction with the solar wind. Ionospheric sounding is a well-known technique at the surface of the Earth which has proven to be very useful for the study of the lower ionosphere. The principle is to transmit a radio pulse vertically and to measure the time which elapses before the echo is received. By varying the frequency of the pulse carrier wave, a plot can be obtained of echo delay versus frequency. It gives information about the propagation medium. The scientific objectives are described which can be achieved with such an experiment and the parameters which can be measured underlining the specificity of the Martian atmosphere are given. The theoretical scientific background of this sounder is briefly described and, finally, its feasibility is discussed.