Challenges during Metis-Solar Orbiter commissioning phase

Metis is the visible light and UV light imaging coronagraph on board the ESA-NASA mission Solar Orbiter that has been launched February 10th, 2020, from Cape Canaveral. Scope of the mission is to study the Sun up close, taking high-resolution images of the Sun’s poles for the first time, and understanding the Sun-Earth connection. Metis coronagraph will image the solar corona in the linearly polarized broadband visible radiation and in the UV HI Ly-α line from 1.6 to 3 solar radii when at Solar Orbiter perihelion, providing a diagnostics, with unprecedented temporal coverage and spatial resolution, of the structures and dynamics of the full corona. Solar Orbiter commissioning phase big challenge was Covid-19 social distancing phase that affected the way commissioning of a spacecraft and its payload is typically done. Metis coronagraph on-board Solar Orbiter had its additional challenges: to wake up and check the performance of the optical, electrical and thermal subsystems, most of them unchecked since Metis delivery to spacecraft prime, Airbus, in May 2017. The roadmap to the fully commissioned coronagraph is here described throughout the steps from the software functional test, the switch on of the detectors of the two channels, UV and visible, to the optimization of the occulting system and the characterization of the instrumental stray light, one of the most challenging features in a coronagraph. © 2021 ESA and CNES