Observing Periods ∼20 days of data All the mission
Regions Active Regions, Coronal Holes (& boundaries), Quiet Sun Full Sun
Subjects Solar Wind, Eruptions, SEP Release, Reconnection events, Flares CME launch, EIT/Moreton waves, SEP and Flares location on the Sun

Preliminar observational program.

Observed Region and Observing Plan

EUI (expecially the HRIs) will provide us informations about the plasma dynamics with a high spatial and temporal resolution from the chromosphere up to the corona. It will be possible to trace global events (such as EIT and MORETON waves) at different altitudes on the solar atmosphere but also follow the evolution of emerging and/or erupting structures (such as filaments, prominences, CME).
The mayor limitations in the exploitation of the EUI capabilities come from the telemetry. The amount of data that can be collected by the instrument far exceeds the transfer capability allowed by the spacecraft's orbit. for the entire duration of the mission. Since FSI must be operating during the entire mission, the HRI outputs cannot be collected continuosly. Although the telemetry problem is partially solved by the data compression, an observational program becomes unavoidable for the HRIs. As surmarized in the table, they will be switched on during particular periods of interest (depending on the vairuos parameters, such as the distance from the sun, the inclination, the corotation, request from other instruments on board Solar Orbiter, see below and here for more details on the program).

Impact of the orbit on EUI performances


Illustration of the FSI FoV variations. The red box gives the size of the HRIs FoV.

To resume some of the effects of the orbit, the distance to the Sun varies continuously with a factor 3.9, during the nominal mission phase (after Sept. 2018); the inclination with respect to the ecliptic evolves; the spacecraft is in quasi corotation for brief periods, representing windows for special observational programs (compared to the preliminary standard programs). Additionally, the level of co-rotation decreases when the mission extends in its higher latitude phase. The fact that the S/C-Sun-Earth angle is different at each orbit has several scientific implications.


Movie [25Mb] showing the variation of the FoV of FSI throughout the mission timeline.
The Sentinels spacecrafts are also shown within the FoV of the instrument (see the text for an explanation). (click on the image to start the movie, or download the appropriate software)

The movie to the right (click on the image) shows the Sun observed with the FSI instrument during the lifetime of the Solar Orbiter mission. It is a realistic illustration of what the instrument will see, in the sense that the estimated orbit is used to compute the angle and distance under which the Sun will be seen from the probe. more ...

To the upper right, the positions of the Sun (yellow), Earth (blue), Venus (orange), Solar Orbiter (white) and Sentinel (light blue) spacecrafts are shown. The square box delineates a subfield of 2048×2048px within the 4k×4k detector used for FSI. To save telemetry and keep sufficient spatial resolution, only this subfield will be downloaded to the ground during most of the mission, except near the perihelion, when the full picture will be collected.
This simulation is based on a launch scenario in May 2015, whose details are given in the section Launch and Orbit. The movie at 174 Å is based on a realistic but somehow simple model of the electron density and temperature distribution in the solar corona. The movie at 304 Å is based on synoptic maps of the SOHO/EIT instrument, mapped on a sphere and displayed from the appropriate viewpoint. This movie is as well synchronized with the period of the solar cycle corresponding to the 2015 scenario. Although the launch has been postponed to 2017 this movie is still representative of the instrument's FOV, however the synchronization with the solar cycle is obviously not valid anymore.