Sun Synchronous Orbit Flag

Some satellite operators will manoeuvre the satellite to keep it within the defined nominal SSOClosed orbit. This occurs for many operational satellites (e.g. Landsat, Radarsat,Spot, etc).

Knowing this SaVoir can make assumptions for long term orbit analysis by extrapolation of the current defined orbit. This assumption is implemented through the Sun Sync Modifier in the Orbit section of the satellite configuration file.

When a satellite orbit is configured with the Sun Sync Modifier the satellite will show a little Sun icon at the left of the satellite name.

Sun Sync Modifier

The Sun Sync Modifier is defined in the Orbit section of the Satellites configuration file. It implies the definition of a Modifier flag and RCClosed and CLClosed parameters.

The Sun Sync Modifier modifier tells the orbit propagator to handle orbit calculation as follows:

Error detection

If the satellite is not kept within the defined SSO an inconsistency will occur between the Nominal Orbit Period and the Orbit Period of the state vector.

If the difference between both periods is higher than 0.2 seconds (*) a warning will be displayed in the Scenario Pane (Sun icon with exclamation mark) and the Orbit Properties grid (Period Difference in red). In that case it is advisable to update the Satellite configuration file, removing the Sun Sync Modifier.

(*) The alarm threshold is set to 0.2 seconds by default, but can be changed in Edit / Properties / Satellites / Orbits / Sun sync threshold


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