Constraining IPH properties at 1.5 AU using MAVEN observations

International audienceThe flow of neutral H atoms through the heliosphere is referred to as Interplanetary Hydrogen (IPH). The Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft has a high-spectral resolution echelle channel on board its Imaging Ultraviolet Spectrograph (IUVS). IUVS is capable of separating Mars at-rest H emissions from IPH emissions when there is sufficient Doppler shift between the two H populations along the instrument line of sight. Some of the known properties of the IPH population include the flow direction, velocity, UV irradiance, and temperature. When monitored over a solar cycle, the IPH properties can be used to identify variations in local (solar) processes as well as to constrain models that identify dynamics of external (interstellar) interactions, where the IPH flow originates. In this work, fortuitous observations of IPH, obtained from the MAVEN echelle channel across the mission timeline, are analyzed to obtain IPH brightness and thermal broadening. These properties are monitored over the last Solar Cycle to examine trends with solar activity and to empirically constrain IPH models at 1.5 AU to refine our understanding of how our solar system interacts with the Local Interstellar Medium