Exact repeat orbit

The wizard will generate a suitable orbit state vector compliant with the exact track repetition requirement, by specifying the following parameters:

- Repeat cycle (RC): number of days in which the orbit track repeats itself. The RC is expressed as rounded integer number, although the exact repetition period is not exactly an integer number of days.

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

- Inclination: Orbit inclination.

With these three parameters, the semi-major axis will be defined.

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

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

Select other orbit parameters

- 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 at Anx: Specify the orbit epoch at an ascending node crossing.