Heliospheric Science From Gateway With HERMES 

<p>The Heliophysics Environmental and Radiation Measurement Experiment Suite (HERMES) is a multi-instrument science payload that will attach to the HALO module of the Artemis Program&#8217;s Gateway lunar outpost.&#160; HERMES instrumentation includes an electron electrostatic analyzer, an ion mass spectrometer, a proton and electron telescope for energetic particles, and a set of magnetometers. After Gateway arrives in its polar lunar orbit, HERMES will conduct a science campaign that addresses objectives in heliospheric and magnetospheric physics.&#160; Analysis of the in-situ measurements from HERMES will leverage observations from other space missions. &#160;Of note are the 2 THEMIS/ARTEMIS probes already in lunar orbit.&#160; They provide measurements of particles and fields that can be compared directly with those from HERMES.&#160; With this small constellation of spacecraft it will be possible to analyze structures in the solar wind, such as CMEs and SIRs, on scales ~11 Earth radii (70,000 km).&#160; HERMES also serves as a pathfinder for future space-weather payloads as may be carried on deep-space missions of exploration for which local measurements of space-weather can contribute to accuracy of predictions and thereby contribute to crew safety. The HERMES science teams will share data and work closely with scientists from ESA&#8217;s European Radiation Sensors Array (ERSA) and with those of the joint ESA/JAXA Internal Dosimeter Array (IDA). HERMES data at all levels will be fully open and accessible through NASA's Space Physics Data Facility to enable independent analyses.&#160; In this presentation we provide an overview of science plans, including expectations for collaboration with international partners and with other science missions.&#160;</p>