Information on this page is taken from the Solar Orbiter Consolidated Report on Mission Analysis (CReMA), issue 5.0 and updated with some changes post-launch.
This page serves to provide a brief overview of Solar Orbiter's trajectory to aid in planning for GAMs, conjunctions etc. More detailed information for each planning period can be found in the Science Planning pages, and orbit plots and animations per planning period can be found on the Orbit Plots page.
An animation of the orbit for the entire mission can be found here: Orbit_Whole_Mission.mp4
Launch Window, Launch Date and Mission Phases
The launch window nominally opens on 4 February 2020 and closes on 24 February 2020, although launcher performance margins mean that an earlier launch is possible. Actual launch took place at 04:03 UTC on 10 February 2020.
Currently, mission phases are planned as follows, the start of cruise phase is subject to change based on the actual duration of commissioning activities.
|Nominal Mission Phase||2021-11-26|
|Extended Mission Phase||2026-01-01|
Perihelion Distances and Orbit Inclinations
Solar Orbiter's trajectory evolves through the mission via gravity assist manoeuvres with Venus and Earth. These imply some planning constraints (see below) but in the intervals between behave in the same way in terms of perihelion distance and inclination. the table below summarises each set of orbits with common characteristics. Note that cruise phase orbits aren't included in this table.
|Start Date||Perihelion Distance (AU)||Min Solar Lat (deg)||Max Solar Lat (deg)||Number of Orbits|
Planning Constraints: Gravity Assist Manoeuvres, Conjunctions and Safe Mode Blackouts
Gravity Assist Manoeuvres
The orbits with different characteristics in the table above are separated by gravity assist manoeuvres (GAMs). Therese are all with Venus within the science phases. The GAM that marks the transition from cruise to the nominal phase is the only Earth encounter on this trajectory.
Periods 28 days prior and 7 days subsequent to each GAM are the so-called navigation windows. Payload operations are restricted during these windows since critical platform activities may take place at any time and at short notice. Remote sensing instruments will not operate and in situ instruments who wish to operate must agree a clear set of operational constraints and simple OFF/ON procedures with MOC, such that the flight control team can command instruments in response to spacecraft activities outside of the usual planning cycles.
|GAM||Restrictions Start||Closest Approach||Restrictions End|
Note that EOM is currently assumed to be VGAM8
In the case of Solar Orbiter, a solar conjunction is defined as an interval where the Sun-Earth-Spacecraft angle is <= 3 degrees. During these intervals communications with the spacecraft are unlikely to be possible, so no payload commanding or science data downlink will take place.
A superior conjunction is when the spacecraft is on the far side of the Sun compared to Earth. An inferior conjunction is when the spacecraft is directly between the Sun and the Earth.
Conjunction times and durations are as follows: to be updated with actual trajectory
|Type||Start||End||Duration (days)||Min SES (deg)|
Safe Mode Comms Blackouts
Safe mode communications blackouts occur under similar circumstances to conjunctions, when the Sun - Earth - Spacecraft Angle <= 5 degrees, and also when the Sun-Spacecraft-Earth angle <=3 degrees. Thus conjunction periods are often nested inside safe modes comms blackout periods.
Safe mode comms blackout intervals are intervals where contact with the spacecraft will be lost in the event of a spacecraft safe mode because the Medium Gain Antenna will not be sufficient to communicate with ground. Spacecraft safe modes are of course unlikely, however critical activities should be avoided during these intervals if possible.
to be updated with actual trajectory
Note that only safe mode comms blackouts with duration longer than 7 days are included in the above summary table.