Earth Observation Missions provide continuous surveillance of the Earth regardless of atmospheric conditions producing huge amounts of data every year that need to be processed, elaborated, appraised and archived by dedicated systems. Emerging institutional and international environmental initiatives, like the ESA and EC Global Monitoring for Environment and Security (GMES), require access to full historical data collections, including the performed data elaborations, scientific analysis, models and results. The historical ESA Earth Observation archives account for Petabytes data holding, which is augmented, since the launch of Envisat in 2002, by some 500 Terabytes per year. The access and utilisation of these archives is an important measurement for long-term data preservation; improving it is a continuous challenge at programmatic, technological and operational level. This article describes how Digital Library and Grid technology can support the underlying infrastructure for long-term data preservation.