THE MARS EXPRESS MISSION

Mars Express is a scientific remote sensing spacecraft currently in orbit around Mars. The project is managed by the European Space Agency, and includes scientific participation by most European countries as well as Russia, Japan and the United States. The spacecraft was launched in June 2003 and arrived in Mars orbit on 25 December 2003. It is currently in a highly elliptical, polar orbit with a period of about 7 hours. Each orbit the spacecraft approaches to within 300 km of the surface; the latitude and solar illumination conditions at close approach drift slowly with time, such that all of the planet will be accessible to the science instruments during the first Mars year of operations. The scientific payload consists of seven instrument packages, including a camera, three spectrometers, a neutral atom analyzer, a radar sounder, and a radio science experiment that utilizes the telecommunications system. After a brief period of commissioning, the instruments began collecting science data in January 2004. Among the notable results to date are: remarkable 3D color images of a wide array of Martian landforms from the High Resolution Stereo Camera (HRSC); detailed mapping of the distribution of water ice and CO2 ice on the south polar residual ice deposits by the OMEGA and SPICAM spectrometers; intriguing signatures of sulfate minerals by OMEGA; and a possible detection of trace amounts of atmospheric methane by the Planetary Fourier Spectrometer (PFS). The radar sounder, known as MARSIS, is designed to probe the subsurface of Mars down to depths of several kilometers. The radar echoes will be used to detect material discontinuities in the subsurface, which may indicate the presence of groundwater or ice, and boundaries of geologic units and structures. As of this writing, the MARSIS experiment is delayed due to concerns over the deployment of its twin 20-meter antennas.