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NEWS FEATURE
The View From Europe
ESA ships home images from the Mars Express
February 2004
On Christmas Day, the European Space Agency (ESA) launched Mars Express. A few weeks later, the Mars Express brought home images of the planet’s surface. On January 23, the ESA held a press conference showing a 3D video sequence of the planet’s surface for the first time “as seen through European eyes,” according to ESA.
But it wasn’t just one instrument that brought these images back to Earth. It was a whole array of imagers.
HIGH RESOLUTION STEREO CAMERA
The High Resolution Stereo Camera (HRSC) was originally designed for the Russian Mars space mission in 1996, but when the launch was unsuccessful, the backup model was modified for use on the European Mars Express mission. Another version, the HRSC-AX, has been built for airborne high-resolution 3D Earth reconnaissance and has already been used in a large number of projects.
The camera head has a resolution of 10 meters per pixel at an altitude of 250 kilometers — the point of closest approach to Mars. The Super Resolution Channel (SRC) part is the high resolving channel with a resolution down to 2.3 meters per pixel. The electronics are based on the same principle of a linescan camera. This means that, unlike a 35mm camera, only a line is exposed to the light instead of the whole area. One CCD line of the HRSC consists of 5,184 pixels. The HRSC has nine of these lines, one for each imaging channel. The CCD exposure time is adjusted to match the ground velocity of the spacecraft.