Sun Synchronous orbit

The wizard will generate a suitable orbit state vector compliant with the sun synchronicity requirement, by specifying the following parameters:

- Repeat cycle (RC): number of solar days in which the orbit track repeats itself.

- Cycle length (CL): exact number of orbits in one repeat cycle.

With these two parameters, the semi-major axis and orbit inclination will be defined.

Both RC and CL need to be defined together. When editing them, a dialogue window appears to define the RC/CL couple. Alternatively, it is possible to specify the desired approximate orbit height to obtain a suitable RC/CL pair.

Click "Apply" to see a list of suitable RC/CL combinations for the desired orbit height, and select one accordingly.

 

Select other orbit parameters

- MLST at ANX (Mean Local Solar Time at the Ascending Node Crossing), also called LTAN (Local Time at the Ascending Node). It defines the orientation of the orbit plane with respect to the sun.

- Argument of the Perigee: select 90 or -90 degrees for a frozen orbit. In this case the suitable eccentricity will be calculated to obtain a frozen orbit, based on the following formula

With

• J2 , J3: zonal harmonics of Earth's geopotential

• i: orbit inclination

• R : Earth's mean equatorial radius

• a: semi-major axis

Anx Longitude: Set the geographical longitude where one ascending node crossing takes place. This will allow to define a precise orbit mean anomaly.

Epoch day: Select the day of the orbit epoch. The precise epoch will be automatically generated with the specified Anx longitude.