The Gaia satellite is a high-precision astrometry, photometry and spectroscopic ESA cornerstone mission, currently
scheduled for launch in late 2011. Its primary science drivers are the composition, formation and evolution of the
Galaxy. Gaia will not achieve its scientific requirements without detailed calibration and correction for radiation
damage. Microscopic models of Gaia's CCDs are being developed to simulate the effect of radiation damage, charge
trapping, which causes charge transfer inefficiency. The key to calculating the probability of a photoelectron being
captured by a trap is the 3D electron density within each CCD pixel. However, this has not been physically modelled
for Gaia CCD pixels. In this paper, the first of a series, we motivate the need for such specialised 3D device modelling
and outline how its future results will fit into Gaia's overall radiation calibration strategy.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.