Soft X-ray Imaging of the Earth’s Magnetosphere

Charged particles and neutral atoms exchange electrons in many space plasma environments. In particular, soft X-rays are emitted when highly charged solar wind ions, such as C⁶⁺, O⁷⁺, and Fe¹³⁺, interact with neutral hydrogen and helium atoms. Soft X-ray imaging can be a powerful technique for remotely probing the plasma and neutral density structures created when the solar wind interacts with planetary exospheres, such as those at Earth, the Moon, Mars, Venus, and comets. For Earth, the magnetosheath and cusp regions where solar wind energy enters the magnetosphere to power space weather are strong soft X-ray emitters because both heavy solar wind ions and exospheric neutrals are more densely populated in these regions than in the surroundings. By observing these signals, we can track the global motion of the bow shock, magnetopause, and cusps in response to solar wind and interplanetary magnetic field conditions. Thus, analyzing near-Earth soft X-ray emissions will advance our understanding of the global interaction between solar wind and geospace. The Solar-Terrestrial Observer for the Response of the Magnetosphere (STORM) is a mission concept for the forthcoming NASA Explorer MIDEX Mission of Opportunity, designed to image the solar wind - geospace interaction in X-ray, ENA, and FUV while simultaneously measuring solar wind plasma and the interplanetary magnetic field along a 30RE circular polar orbit. STORM aims to quantify the global flow of energy through the coupled solar wind-magnetosphere-ionosphere system. This presentation introduces X-ray emission from various planets due to solar wind charge exchange, simulations of expected soft X-ray images of the Earth’s magnetospheric system, and their analysis for the STORM mission.