The concept and optical layout of a limb sounder using a spatial heterodyne spectrometer is presented. The instrument fits onto a nano-satellite platform, such as a CubeSat. It is designed for the derivation of temperatures in the mesosphere and lower thermosphere. The design parameters of the optics and a radiometric assessment of the instrument as well as the main characterization and calibration steps are discussed.

Information on the mesospheric OH layer height is crucial for identifying sources of its variability and causes of discrepancies in measurements and models. Using space-based data, we inferred an empirical function for predicting the altitude of the layer at midlatitudes from ground-based measurements of OH intensity and temperature. By applying it to data at the Sierra Nevada Observatory, we found significant short-term variability in the layer altitude, mainly due to wave variability.