Speaker
Description
Metis, one of the ten instruments of the Solar Orbiter mission, is the first solar coronagraph capable of
performing simultaneous imaging of the off-limb solar corona in both visible and UV light. Due to the
uniqueness of the Solar Orbiter mission profile, Metis has already observed the Sun corona from a
minimum distance of ~0.28AU and is approaching higher latitude views with the increase of the orbit
inclination above the ecliptic plane.
Scope of this paper is to describe the correlation of the Metis temperature measured in flight during the
Solar Orbiter mission at different solar distances (from the first aphelion at 0.952 AU to the first perihelion
at 0.52 AU and to the one of the closest perihelion at 0.292 AU) with those predicted from the Metis
thermal model correlated with the ground tests.
Objectives of this correlation were to validate the prediction of the instrument thermal behaviour in all
flight conditions, to provide recommendations about the temperature ranges to be applied at the
interfaces between the Metis detectors (VLDA, UVDA) cold fingers and the spacecraft interfaces during
the scientific acquisitions and the VLDA annealing, and to compute the temperatures reached by the
internal optical elements in off-pointing from the sun-centred condition with the Metis external door open.
The comparison with the flight data demonstrated the validity of the Metis thermal model resulting from
the correlation with the data of the thermal-balance test campaigns performed first on the STM with Sun
Simulator in ESA/ETS facilities and finally on the PFM in TAS-I Rome facility. In fact, it has been verified
that the thermal model correctly predicts within the uncertainty values the temperatures measured inflight from the aphelion to the minimum perihelion.
Keywords: Coronagraph, Thermal Correlation, Sun simulator, ESATAN-TMS, flight data