Current three-dimensional, data-based models for the terrestrial exosphere have been derived from measurements of optically thin Lyman-alpha (Ly-α) emissions scattered by neutral hydrogen atoms. Such models are only valid for the middle exospheric region (3-8 Earth radii geocentric distances) since the orbital paths of the space-based platforms used to acquire Ly-α radiance were located within the exosphere, thus precluding the proper detection of the faint outer exospheric emission. Notwithstanding, accurate specifications of density distributions beyond 8 RE are needed to support comprehensive studies of the solar-terrestrial interactions. Two upcoming missions, the Solar wind Magnetosphere-Ionosphere Link Explorer (SMILE) and the Lunar Environment Heliospheric X-ray Imager (LEXI), will image the Earth’s magnetosheath in soft X-rays, and neutral densities are crucial to extract ion distributions through inversion of the acquired images. This work develops a technique to estimate the Earth’s outer exospheric density distributions using far-ultraviolet wide-field data acquired by the Lyman-Alpha Imaging Camera (LAICA) onboard the Proximate Object Close Flyby with Optical Navigation mission. Our approach formulates an inverse problem based on the linearity between measurements of scattered Ly-α flux and the local atomic hydrogen density, which is solved using the Bayesian approach known as Maximum a posteriori estimation. We use the LAICA image to derive global, 3-D hydrogen density distributions at 6-35 RE geocentric distances. We find that the spatial structure of the outer exosphere agrees well with the predictions of radiation pressure theory. Further, we find that the mean hydrogen density at 10 RE subsolar point is 26.51 atoms/cm3.

The Solar Dynamics Observatory (SDO) is a solar mission in an inclined geosynchronous orbit. Since commissioning, images acquired by Atmospheric Imaging Assembly (AIA) instrument on-board the SDO have frequently displayed “spikes”, pixel regions yielding extreme number of digital counts. These are theorized to occur from energetic electron collisions with the instrument detector system. These spikes are regularly removed from AIA Level 1.0 images to produce clean and reliable data. A study of historical data has found over 100 trillion spikes in the past decade. This project correlates spike detection frequency with radiation environment parameters in order to generate an augmented data product from SDO. We conduct a correlation study between SDO/AIA data and radiation belt activity within the SDO’s orbit. By extracting radiation “spike” data from the SDO/AIA images, we produce a comprehensive data product which is correlated not only with geomagnetic parameters such as Kp, Ap and Sym-H but also with the electron and proton fluxes measured by the GOES-14 satellite. As a result, we find that AIA spikes are highly correlated with the GOES-14 electrons detected by the MAGED and EPEAD instruments at the equator (where the two satellites meet) with Spearman’s Correlation values of ρ=0.73 and ρ=0.53 respectively, while a weaker correlation of ρ=0.47 is shown with MAGPD protons for the two year period where both missions returned data uninterruptedly. This correlation proves that the SDO spike data can be proven useful for characterizing the Van Allen radiation belt, especially at areas where other satellites cannot.