Asteroids are components of a very large family of the Solar System. We denote more than 590 000 such objects at the present date. As soon as there is a discovery of an asteroid, a preliminary orbit can be calculated and the improvement of this orbit can be performed thanks to new observations to be done starting from their discovery. But ancient observations can also be retrieved in the past. The data mining allows us to find these old observations in archives. We present general considerations on the asteroid orbital precision in this article and the very important impact of the future Gaia catalogue. We show the expected consequences for the study of Near-Earth Asteroids, in particular for 99942 Apophis.