The drift scanning technique offers, in principle, a simple and effici
ent method for imaging wide regions of the sky with intrinsic high ast
rometric accuracy. its performance is analyzed in two distinct environ
ments, namely from a small class ground based telescope and a spacebor
ne interferometer. In particular, the study is referred to the propose
d ESA cornerstone mission GAIA (Global Astrometric Interferometer for
Astrophysics). The constant clock rate of a CCD, due to the declinatio
n dependent sidereal speed variation, results in a systematic image sm
earing, which Limits the positional accuracy. Moreover, the readout ti
ming accuracy provides an additional random noise corresponding to a d
rift speed jitter. Stability requirements on the order of 10(-6) or be
tter have to be fulfilled for the space option. Both effects can be ad
dressed by proper system design; provisional implementation strategies
are discussed for both applications.