Astrometry from space was performed for the first time and with great success by the ESA Hipparcos satellite (1989-93). This mission was designed as an as trometry mission, but the use of a photon counting detector made it possible to produce very important photometric results: the most accurate astronomical pho tometry ever by the main Hipparcos mission in a very broad band of 120000 stars, and the two-colour Tycho-2 photometry of 2.5 million stars. The cornerstone ESA mission GAIA was approved in October 2000 for launch not later than 2012. This mission will use CCDs in time-delayed...