An apparatus for determining the attitude of an orbiting spacecraft includes an optical system for generating an image on a substrate of a body around which the spacecraft is orbiting, an infrared detector positioned on the substrate in the form of a non-cooled two-dimensional array of pixels disposed in a spaced relationship forming rows and columns, the rows extending in a first direction, and the columns extending in a second direction perpendicular to the first direction, a scanner and an addressing controller for the scanner, the controller and the scanner cooperating to scan the pixels along a predetermined scan path which zig-zags between adjacent rows and columns of pixels, and a computation circuit responsive to the succession of pixel output signals along the scan path to calculate pitch and roll angle changes of the spacecraft according to changes in the image of the orbited body in the first and second direction.
