ABSTRACT Over the past few years, a joint Swiss/Belgium ESA initiative resulted in a project to build a precursor mission of future spaceborne imaging spectrometers, namely APEX (Airborne Prism Experiment). APEX is designed to be an airborne dispersive pushbroom ,imaging spectrometer operating in the solar reflected wavelength ,range between ,400 and 2500 nm. The system is optimized for land applications including limnology, snow, and soil, amongst others. The instrument isoptimized with various steps taken to allow for absolute calibrated radiance measurements. This includes the use of a pre- and post-data acquisition internal calibration facility as well as a laboratory calibration and a performance,model serving as a stable reference. The instrument is currently in its breadboarding phase, including some new results with respect to detector development and design optimization for imaging spectrometers. In the same APEX framework, a complete processing and archiving facility (PAF) is developed. The PAF not only includes imaging spectrometer data processing up to physical units, but also geometric and atmospheric correction for each scene, as well as calibration data input. The PAF software includes an Internet based web-server and provides interfaces to data ,users as well ,as instrument operators and programmers. The software design, the tools and its life cycle are discussed as well. Keywords: Imaging ,spectrometer; hyperspectral; pushbroom; calibration; validation; sensor design; data processing;