Silicon and Aluminium Gallium Nitride photodetectors have been calibrated for use on the Southampton Transient Oxygen and Radiation Monitor (STORM), part of the Materials Exposure and Degradation Experiment on the European Technology Exposure Facility. The detectors will monitor the Solar SXR and UV dose levels over a period of three years while situated in Low Earth Orbit (LEO) on the International Space Station. Calibration of the detectors included measuring their spectral responsivity, spectral transmission of filters, sensitivity to electron bombardment, sensitivity to angle of incidence of electromagnetic radiation, proportionality of response to electromagnetic radiation and ability to withstand launch-simulating vibration loads. With respect to the AlGaN detectors this calibration represents novel work and, consequently, the design and development of the STORM instrument suite represents a unique engineered structure for the application of LEO environment monitoring. Additional material includes: literature reviews of space materials exposure research, Solar generation of SXR and UV, previous spacecraft usage of SXR and UV detectors for Solar dose monitoring, and the development of AlGaN photodiodes; and a discussion involving the expected behaviour of the detectors on-orbit, potential sources of interference with possible mitigation strategies, and predictions of the amount of data to be returned throughout the mission.