Stardate 20010725.1810 (On Screen): Mars Global Surveyor continues to provide enormously fruitful data about the surface of Mars, and continues a long tradition of new probes telling us things which are completely unexpected. The majority of the most fabulous data being returned by this mission is coming from its camera. This is actually the second attempt at this; the first was one of those famous failed Mars missions, but the team which created it had a spare camera and put it onto a second craft which succeeded in reaching and orbiting the planet. One of the things which is cool about this camera is how small it is. It doesn't have a square grid; it's CCD is a line which is only one pixel wide. Instead of a round lense it has a slit. And when it is used, the slit is perpendicular to the motion of the craft. As the craft moves over the ground, it continuously snaps one-pixel wide images which it strings together. That's why MGS images seem to be long stripes; it keeps capturing these images until it runs out of memory. Then it transmits that data back to Earth at a somewhat slower rate. The data is captured far faster than the radio link can handle, and in any case part of the time the craft is behind Mars and not in contact with Earth. But this clever use of the proper motion of the craft means that the camera can be much smaller, and more importantly, weigh less than if it was a conventional square image camera, while capturing much larger images than a square camera could.
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