Abstract . A first-generation CMOS Charged Particle Spectrometer chip [1] was designed at JPL for flight on the STRV-2 spacecraft. These devices will collect electron and proton spectra in low Earth orbit as part of an experiment to demonstrate Active Pixel Sensor (APS) technology in space. This paper presents the results of total dose testing on these chips and, where possible, attempts to extend the results to other Active Pixel Sensors. ...