Simplify, downsize and reduce power of devices which comprise the satellite navigation system used in approach and docking in space. The navigation system 1 which estimates an attitude of a target object T in space comprises: an optical marker 10 that is attached to the target T and reflects light; a lighting device 20 that irradiates the target object T with light of a predetermined wavelength band; an image acquisition device 30 that acquires an image of the optical marker 10 which has reflected the light of the predetermined wavelength band; and an image processing device 40 that processes the image acquired by the image acquisition device 30 and thereby estimates the attitude of the target object T. The lighting device 20 and the image processing device 30 are loaded on an aerospace vehicle 2.