Maven Sep Observations Of Scorpius X-1 X-Rays At Mars: A Midatmosphere Occultation Analysis Technique

We report on the first observations of atmospheric occultations at Mars of similar to 10 keV X-rays from an extrasolar source identified as Scorpius X-1. The measurements are taken by the SEP (Solar Energetic Particle) instrument on the MAVEN (Mars Atmosphere and Volatile EvolutioN) spacecraft. The detected X-ray photons from Scorpius X-1 penetrate the Martian atmosphere down to similar to 70 km altitude, before being attenuated by the neutrals in the atmosphere. The occultation altitude varies by a few km depending on the source X-ray energy and the atmospheric neutral density. In this work, we study the detection response of SEP to Scorpius X-1 X-rays and demonstrate that X-ray occultation data can be used in conjunction with a model of the light extinction curve in order to gain insights into the neutral density of the Mars atmosphere in the 50-100 km altitude range, an important and largely unexplored altitude range at Mars.