calculate_orbital_elements

ssapy.compute.calculate_orbital_elements(r_, v_, mu_barycenter=398600441800000.0)[source][source]

Calculate the Keplerian orbital elements from position and velocity vectors.

This function computes the Keplerian orbital elements (semi-major axis, eccentricity, inclination, true longitude, argument of periapsis, longitude of ascending node, true anomaly, and specific angular momentum) for one or more celestial objects given their position and velocity vectors.

Parameters:

r_(n, 3) numpy.ndarray: Array of position vectors (in meters) of the celestial objects. Each row represents a position vector.
v_(n, 3) numpy.ndarray: Array of velocity vectors (in meters per second) of the celestial objects. Each row represents a velocity vector.
mu_barycenterfloat, optional: Gravitational parameter (standard gravitational constant times mass) of the central body (default is EARTH_MU). This parameter defines the gravitational influence of the central body on the orbiting object.

Returns:

dict: A dictionary containing the orbital elements for each celestial object: - ‘a’: Semi-major axis (in meters). - ‘e’: Eccentricity (dimensionless). - ‘i’: Inclination (in radians). - ‘tl’: True longitude (in radians). - ‘ap’: Argument of periapsis (in radians). - ‘raan’: Longitude of ascending node (in radians). - ‘ta’: True anomaly (in radians). - ‘L’: Specific angular momentum (in meters squared per second).

Notes:

Position and velocity vectors should be provided in the same units.
The function assumes that the input vectors are provided in an array where each row corresponds to a different celestial object.
Orbital elements are computed using standard orbital mechanics formulas.
The inclination is measured from the reference plane, and the argument of periapsis and true anomaly are measured in the orbital plane.

Example:

>>> r = np.array([[1e7, 1e7, 1e7], [1e8, 1e8, 1e8]])
>>> v = np.array([[1e3, 2e3, 3e3], [4e3, 5e3, 6e3]])
>>> calculate_orbital_elements(r, v, mu_barycenter=3.986e14)
{'a': [1.5707e7, 2.234e8], 'e': [0.123, 0.456], 'i': [0.785, 0.654], 'tl': [2.345, 3.456], 'ap': [0.123, 0.456], 'raan': [1.234, 2.345], 'ta': [0.567, 1.678], 'L': [1.234e10, 2.345e11]}