Seven instruments to find life on Mars

Mars Mars Express is the most promising scientific mission ever undertaken by Europe.

The High Resolution Stereo Camera (HRSC) is a masterpiece of optics developed and built by its prime contractor, EADS Astrium GmbH, Friedrichshafen, originally for the unsuccessful Russian “Mars 96” mission . At the same time, EADS Astrium had built a second camera for test purposes. After the "Mars 96” accident, this model was modified for Mars Express. Instead of the originally planned ground resolution of up to ten metres, it was now required to detect pram-sized details from a distance of 250 kilometres. This was made possible by the integration of an additional high-resolution stereo channel developed and built by the German Aerospace Centre (DLR). Four other channels supply colour images and two channels are required for photometric measurements. A special feature is the possibility to produce stereo images.

With this wide variety of observation modes, HRSC opens a multitude of prospects for the planetary scientists. It will, for instance, be used to search for signs of former oceans or rivers. It is assumed that the arctic region was previously covered with water as a wide plain is clearly visible with boundaries that strongly resemble a coastline. Thanks to its high resolution, the HRSC is able to provide further information on this.

Once Mars Express is in its elliptical orbit, its seven scientific instruments can begin to study Mars for between 30 and 60 minutes per orbit, when it is closest to the planet. At this point the spacecraft is nadir pointing during pericentre passes. It can collect the scientific data from the Beagle 2 Lander and store it on board until it can transfer it, during Earth communications sessions, when it is 3-axis stabilised and Earth pointing.

With its high resolution stereo camera, Mars Express will provide three-dimensional photos of the Mars surface of unrivalled quality. With its radar instruments, the probe will also be able to "see" under the planet’s surface and will be able to gather information about the structures and materials underneath. Even the presence of subterranean water can be confirmed with the help of these radar instruments. Furthermore, Mars Express will investigate the atmosphere and the climate of the Red Planet.

The other instruments on board Mars Express include:

• Marsis is a radar instrument, which scans the planet’s surface.
• The radar waves reflect off the surface structure down to the permafrost, which means that it can penetrate between two and three metres beneath the surface. This enables both the investigation of the composition of the different rock strata and the search for the presence of subterranean water.

• Aspera, which investigates the influence of solar wind on the Mars atmosphere, by studying the interaction of the atmosphere with the interplanetary medium.

• Mars, which scans the surface and atmosphere of the Red Planet with radio waves.

• Omega, a spectrometer for the investigation of minerals on the Mars surface and the composition of its atmosphere.

• PFS, which explores the distribution of water vapour in the atmosphere.

• Spicam, which generates the vertical profile of the distribution of carbon dioxide, ozone and aerosols and, furthermore, measures the temperature and observes the clouds.