9. ThreeBodyGravity#

class ThreeBodyGravity(state_vector: StateArray, pnt_masses: list, base_frame: Frame)#

Attributes

Methods

`compute_acceleration`(position, ...)	Compute third-body gravitational acceleration.
`compute_partial_by_position`(position, ...)	Compute da_3b/dr for third-body gravity.
`compute_partial_by_third_body_position`(...)	Compute d a_3b / d r_origin->pm for a specific third body (point mass).

compute_acceleration(position: ndarray, current_state: dict, epoch: float, body: CelestialBody) → ndarray#

Compute third-body gravitational acceleration.

If a third body is propagated in the state vector, its position is taken from current_state; otherwise SPICE is used.

compute_partial_by_position(position: ndarray, current_state: dict, epoch: float, body: CelestialBody) → ndarray#

Compute da_3b/dr for third-body gravity.

Uses propagated third-body positions when available; otherwise SPICE.

compute_partial_by_third_body_position(position: ndarray, current_state: dict, epoch: float, body: CelestialBody, point_mass_name: str) → ndarray | None#

Compute d a_3b / d r_origin->pm for a specific third body (point mass).

Returns 3x3 if that point mass is propagated in the state. Returns None if not propagated (because then origin2pm comes from SPICE, not a solve-for).