Mission Planning for Stellar Occultation Measurements of Lower Thermospheric Nitric Oxide in the Polar Night

A tool has been developed using MATLAB and Ansys Systems Tool Kit to support the design and mission planning for a CubeSat form-factor instrument that will investigate the altitude distribution of nitric oxide in the polar night. Measurement of nitric oxide in the polar night is critical for improving understanding of the coupling of the Sun-Earth system through the generation of nitric oxide and its impact on the structure of the atmosphere. The instrument uses a novel ultraviolet optical design with a delta-doped electron multiplying charge coupled device as the detector. The instrument performs measurements via the stellar occultation technique to determine the density of nitric oxide through photometric measurements of star light at 215 nm, coinciding with the γ(1,0) absorption feature of nitric oxide, before and after it has been attenuated by the atmosphere. The geometry of the satellite orbit and target star determine the corresponding geographic location of the measurement, requiring a consideration of both star brightness to achieve the required signal-to-noise ratio for the photometric measurement, as well as the location of the star to ensure that measurements correspond to the polar regions. In this work, we analyze orbits and target star selections for performing stellar occultations in the Arctic and Antarctic winters. We show that a Sun-synchronous orbit demonstrates the ability to perform stellar occultation measurements using the star α Canis Majoris at consistent latitudes during the December solstice, enabling the study of nitric oxide density over the course of Arctic winter.