Like mariners of old, spacecraft steer by the stars – using combinations of telescopes, cameras and computers called startrackers to recognise stellar constellations to calculate their own position in space. The test bench seen here generates an artificial star-like light source to test the optical performance of startrackers.
https://www.esa.int/ESA_Multimedia/Imag ... icial_star
Funny that, I used to use a torch with tin foil over it and a pin hole in the middle!
Graeme