Repeat cycle calculation of a Sun-Synchronous orbit (SSO)

Hello everyone,

I'm wondering if anyone can help me with a question I have. I'm trying to calculate the repeat cycle of a Sun-Synchronous orbit (SSO) with Satellite Communication Toolbox functions, but I haven't found a function that gives this capability.

¿There is any method included in the Satellite Communication Toolbox (or in other Toolboxes) to calculate this repeat cycle?

Note: I'm trying to calculate the repeat cycle, not the orbit period. In SSO orbits this is not the same.

I would really appreciate any help or advice you can provide.

Thank you!

Answer 1

[Praveen Reddy]

Hi César,

I understand that you are trying to calculate repeat cycle of SSO and would like to know if there are any available functions with Satellite Communications Toolbox to achieve the task. However, Satellite Communications Toolbox does not have a specific function to calculate the repeat cycle of SSO. A possible work around could be to calculate the repeat cycle of SSO manually using basic orbital parameters, including the semi-major axis, eccentricity, inclination and rotation of the Earth.

Please refer to the following code snippet for a general approach to calculate the repeat cycle of an SSO using MATLAB

% Determine Orbital parameters of the SSO - Usually obtained from satellite
% databases
a = 7000; % Semi-major axis in kilometers
e = 0.001; % Eccentricity
i = 98.5; % Inclination in degrees

% Gravitational parameter of the Earth
mu = 3.986e5; % km^3/s^2

% Calculate mean motion
n = sqrt(mu / (a^3));

% Calculate period
T = 2 * pi / n;

% Calculate number of orbits per day
N = 24 * 60 / T;

% Calculate repeat cycle
R = 1 / (N / 365);

disp(['Repeat Cycle: ' num2str(R) ' days']);

Hope this helps.