Control Networks of the Galilean Satellites: Solutions for Size and Shape

A control network is a series of identifiable points on a surface and a table of their coordinates (latitude, longitude, radius). To create a planetary control network, points (usually craters) are identified on pictures and their image coordinates are measured in pixels. Each control point must be measured on two or more images. The navigation team supplies discrete spacecraft positions and approximate camera-pointing angles. An analytical triangulation program is used to compute the coordinates of the control points and to improve the camera-pointing angles.