The Mars Express Radio Science Experiment (MaRS) started regular operations in April 2004. The experiment employed radio occultation during two occultation seasons in April-August 2004 and December 2004 to sound the neutral martian atmosphere to derive vertical density, pressure and temperature profiles as functions of height, and to sound the ionosphere to derive vertical ionospheric electron density profiles. Both profile types were monitored as functions of time in order to determine diurnal variations and, in the case of the ionosphere, dependence on solar wind conditions. MaRS also determined the dielectric and scattering properties of the martian surface in specific target areas by using bistatic radar, determining gravity anomalies during pericentre passes at altitudes of 250 km for investigations of the structure and evolution of the crust and lithosphere, and sounding the solar corona during the superior conjunction of Mars with the Sun from mid-August to mid-October 2004. This chapter gives, as intended by the project, an overview of the observations from April 2004 to mid-2005, and presents examples and first results.

The success of a scientific mission is determined by the quality of the scientific results. The prompt delivery of instrument and ancillary raw data to the instrument teams and of reduced and calibrated data to the scientific community is therefore a key element in the mission design. This chapter describes the flow of data from the spacecraft through the ground segment via the instrument teams to the final scientific archive. Several software tools and standards are used to support data dissemination. The functionality of the individual tools is explained, the interfaces to the individual groups are discussed, and examples of the graphical user interfaces are shown. Finally, the chapter provides a brief introduction to each of the currently available datasets.

Introduction: Dust devils are temporal and spatial variable surface features. They are recognised as bright spots accompanied by a dark shadow in Martian images (Figure 1). Image data from the various Mars missions are getting more and more voluminous. A Pattern Recognition algorithm is going to be developed which will help to scan and search the images for dust devils. Several questions can then be answered: How often do these phenomenons occur? In which areas can you detect them? How fast are they? What is their height? How long do they last?

The Mars Express Orbiter Radio Science (MaRS) experiment will employ radio occultation to (I) sound the neutral martian atmosphere to derive vertical density, pressure and temperature profiles as functions of height to resolutions better than 100 m, (II) sound the ionosphere to derive vertical ionospheric electron density profiles and a description of the ionosphere through its diurnal and seasonal variations with solar wind conditions; MaRS will also (III) determine the dielectric and scattering properties of the martian surface in target areas by a bistatic radar experiment, (IV) determine gravity anomalies for the investigation of the structure and evolution of the martian crust and lithosphere in conjunction with observations of the High Revolution Stereo Camera as a base for 3D topography, and (V) sound the solar corona during the superior conjunction of Mars with the Sun. The radio carrier links of the spacecraft Telemetry, Tracking and Command subsystem between the Orbiter and Earth will be used for these investigations. Simultaneous and coherent dual-frequency downlinks at X-band (8.4 GHz) and S-band (2.3 GHz) via the High Gain Antenna will permit separation of contributions from the classical Doppler shift and the dispersive media effects caused by the motion of the spacecraft with respect to the Earth and the propagation of the signals through the dispersive media, respectively. The investigation relies on the observation of the phase, amplitude, polarisation and propagation times of radio signals transmitted from the spacecraft and received with antennas on Earth. The radio signals are affected by the medium through which they propagate (atmospheres, ionospheres, interplanetary medium, solar corona), by the gravitational influence of the planet on the spacecraft and, finally, by the performances of the various systems aboard the spacecraft and on Earth.