Faraday cup instrument for the solar wind monitoring at 0.9 AU — HENON mission

The HEliospheric pioNeer for sOlar and interplanetary threats defeNce (HENON) mission funded by the Italian Space Agency has recently advanced to implementation (Phase C). The HENON 12U cubesat is expected to reach a Distant Retrograde Orbit (DRO) of the Sun–Earth system before the end of this decade. For several months it will stay about ≈ 0.1 AU in front of the Earth, providing thus a unique vantage point for the in-situ solar wind monitoring and allowing to send space weather alerts several hours before the related causal geoeffective structures can reach the Earth. The payload of the mission consists of the high-resolution radiation monitor (REPE), magnetometer (MAGIC), and the Faraday cup based solar wind monitor (FCA), provided by the Italian, Finnish, UK, and Czech consortium members. In this contribution we focus to the description of latter sensor — the Faraday Cup Analyzer (FCA), developed at Charles University as a simple and robust sensor for long-term monitoring of the basic solar wind parameters — density, velocity and temperature. We describe the overall instrument design, discuss many important technical aspects of the development including a computer modeling of the most important parts — Faraday cups (FC). We report on results of testing of an FCA development model with newly designed FC sensors, the instrument operation modes and future telemetry data products. As the HENON mission is greatly constrained with limited spacecraft telemetry, we also discuss the data strategy and on-board data processing allowing maximum scientific income and satisfying the mission requirements.