The PASHION mission is a planned small satellite mission that will image the Galactic plane in the Paschen Alpha line. Paschen Alpha can penetrate the interstellar medium (ISM) dust better than Hα, which allows for a smaller telescope to peer deeper into the Galaxy. I have modeled the filter response function to simulate observations for the planned PASHION mission and determine sensitivity limits. Estimates of the unresolved background flux were obtained using the TRILEGAL model. I used the flux of stars in the H and K bands from 2MASS observations to select atmosphere models and interpolate them into the expected Paschen Alpha band. I will show predicted background maps and an initial application of a modeling approach to remove the continuum from Paschen Alpha images.