APEX is an airborne (dispersive push broom) imaging spectrometer developed by a Swiss-Belgian consortium on behalf of ESA. It is intended as a simulator and a calibration and validation device for future spaceborne hyperspectral imagers. Furthermore, APEX is an advanced scientific instrument for the European remote sensing community, recording hyperspectral data in approximately 300 bands in the wavelength range between 400 nm and 2500 nm and at a spatial ground resolution of 2 m to 5 m.
Imaging spectroscopy greatly extends the scope of traditional remote sensing. It is based on the detection of many narrow, contiguous spectral bands. This presents opportunities for more precise identification of surface materials than is possible with broadband multispectral sensors.