The Miniaturized Electron Proton Telescope, MERiT onboard Lunar Gateway

Abstract

<p>The Lunar Gateway or the Gateway, part of NASA’s Artemis program, is a space station that will orbit around the moon. This cis-lunar Gateway platform provides the opportunity for Heliophysics investigations to advance our knowledge of the coupled Sun-Earth system and the opportunity to better understand the radiation environment in order to support and improve crew safety and operations at the Moon and beyond. The Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) is a suite of instruments placed on the outside of the <strong>Habitation and Logistics Outpost</strong><strong> (</strong>HALO)  to monitor the Sun’s radiation environment and space weather. HERMES, led by NASA’s Goddard Space Flight Center, will monitor  solar particles critical to scientific investigations of the Sun including the solar winds. Additonal suite of instruments provided by ESA, the European Radiation Sensors Array (ERSA) will complement space weather studies.</p> <p>We report here on the energetic particle instrument, the  Minaturized Electron Proton Telescope (MERiT) on board HERMES. MERiT is  designed to measure electrons and protons in the energy range ~0.3-9. MeV and ~1-190 MeV in 11 and 20 differential energy channels respectively. MERiT is a solid state detector telescope with  two sensor heads: one looking sunward and the other anti-sunward. MERiT will help advance our understanding of solar energetic particles, low energy cosmic rays and energetic electrons in the magnetospheric tail. We will describe the instrument in detail and the science topics it is expected to address. Lunar Gateway is currently expected to launch in October 2025.</p>