This work presents the development of a new limb-sounder for temperature explorationof the upper atmosphere, the Atmospheric Limb Interferometer for TemperatureExploration (AtmoLITE). It is a miniaturized satellite instrument based aroundthe technique of spatial heterodyne spectrometers. This class of spectrometers iswell suited for miniaturization which allowed to design AtmoLITE within the formfactor of a 6U CubeSat. The observable of AtmoLITE is the rotational spectraldistribution of the day- and night-time oxygen atmospheric band emission, whichis particularly suited for temperature exploration from the lower most mesospheretowards the ionosphere. In addition, this work proposes a novel calibration conceptsuited to accurately characterise the AtmoLITE spectrometers spectral response.Major milestones achieved in this work were (1) the development of the opticalsystem of AtmoLITE, (2) design of an appropriate calibration light stimulus, (3)experimental verification of AtmoLITE in-front of the calibration source, and (4) afirst estimate of expected AtmoLITE temperature retrieval uncertainty.