Navigating through outer space using stars sounds like something out of a science fiction movie, but with modern technology, it is definitely a very real application. Back in 2003, Sigenics designed a wide-dynamic range image sensor for an innovative compact star tracker concept being developed by a NASA research group.
Fifteen years have passed and star tracker technology is now more relevant than ever, with private industry starting to build and launch an ever-increasing variety of space vehicles and satellites. A star tracker is an optical device that senses the positions of stars, and uses this information to determine the orientation of the space vehicle. The sensor for a star tracker faces a difficult challenge: the visual scene may include stars, the Earth (or another planet), the sun, and reflections from other nearby spacecraft or "space junk." The overall visual scene may span many orders of magnitude in apparent luminosity, but the task of discovering spacecraft orientation depends critically on being able to sense an identifiable constellation of stars despite other interfering (and maybe very bright) features.
Sigenics has designed and fabricated several specialized optical sensor arrays which have special features to deal with very wide dynamic range images. These sensors are designed to prevent blooming from very bright image features. Some of the Sigenics sensors include random-access non-destructive readout as well as random-access pixel reset, to allow effective sensing of images which include bright features and deeply shadowed features in a single scene.