The camera that spotted evidence of water in gullies on Mars has a set of eyes that boggles the imagination.

Even from an orbital height of 235 miles (378 kilometers), the camera can spot objects as small as 3 yards (2.7 meters) across.

The Mars Observer Camera

And while the camera can be programmed to run automatically, the camera's designer Mike Malin didn't settle for that; he used the Mars Observer Camera to zero in on specially chosen targets, with surgical precision.

It took some late-1980's state-of-the-art technology and a good deal of old-fashioned ingenuity to make the Mars Observer Camera possible.

The camera's light collector is a telescope with a 3,500-millimeter (138-inch) focal length. It contains mirrors created by computerized grinding technology, similar to the method used for the huge Keck telescope in Hawaii.

Key to the camera's simplicity is a CCD (charge-coupled device) line array that scans a scene one line at a time.

"The same thing is in your fax machine," said Malin. Instead of snapping an entire picture at once, the camera will let the image build up as the spacecraft drifts over the planet.

Because Mars Global Surveyor can only send data to Earth at a slow rate, the images must be stored by the camera and transmitted later, creating an enormous data-handling problem.

A 32-bit microprocessor, using microchips designed by Malin's team, compresses the data as the picture is being taken, to allow up to 12 megabytes of data to be stored for transmission to Earth.

The camera is capable of resolutions as high as a phenomenal 1 *1*/*2* yards (1.4 meters) per pixel (picture element). And the CCD line-array can turn out anything from square images to panoramic swaths.

Meanwhile, two wide-angle cameras snap horizon-to-horizon views. In a single day, these cameras can acquire a complete global image with a resolution of at least 5 miles (8 kilometers) per pixel.

Scientists use these images to study weather patterns and look for changes in large-scale surface markings. The pictures also let Malin and his team establish the precise locations of the closeup views.

Upon its arrival at the Red Planet, Mars Global Surveyor followed a highly elliptical path that looped over the poles. After a series of aerobraking maneuvers, the spacecraft dropped down to a circular polar orbit, and its work began in earnest.

Mars Global Surveyor's mission was slated to last a full Martian year, or 687 Earth days. However, it would surprise no one, given its findings announced this week, if NASA decided to extend the mission -- and the life of Mike Malin's camera.