In-flight verification of the engineering design data for the Energetic Particle Detector on board the ESA/NASA Solar Orbiter

This work presents an overview of the in-flight engineering data of the Energetic Particle Detector (EPD) instrument suite during its first year of operation. EPD is part of the in-situ scientific payload of the ESA/NASA Solar Orbiter mission which was launched in February 2020. After completion of its commissioning phase, Solar Orbiter started its cruise phase in June 2020, in coincidence with its first perihelion at 0.51 au. Six remote-sensing instruments and four in-situ instruments, including EPD, which is a suite of four individual sensors, make Solar Orbiter the most complete space laboratory flown into the inner heliosphere to date. In-flight engineering data of the different EPD units such as their power consumption and their temperatures are the key indicators to ascertain that the design, manufacturing and qualification of the EPD units on ground and throughout the different life cycles prior to launch were successful. On the other hand, these in-flight housekeeping data also reflect the general status of the units which are exposed to space radiation, stray light and a varying thermal environment. The reliability of the EPD suite was analyzed during the design phase and the in-flight status evaluation confirms this analysis. The first year of flight covers special milestones for the Solar Orbiter mission such as the launch, first perihelion, as well as the first Venus flyby. By evaluating the in-flight engineering data, it is demonstrated that the EPD suite successfully meets its design requirements and also satisfies its scientific objectives in flight.