generate_orbit

namespace saltro

namespace orbits

Functions

bool generate_orbit(const Eigen::Vector3d &r0, const Eigen::Vector3d &v0, const Eigen::Matrix<double, 1, saltro::limits::MAX_LENGTH_TRAJ> &jtime, const int jtime_length, const int orbit_model, const int magnetic_model, const int sun_model, const int eclipse_model, const int density_model, Eigen::Matrix<double, 3, saltro::limits::MAX_LENGTH_TRAJ> &R, Eigen::Matrix<double, 3, saltro::limits::MAX_LENGTH_TRAJ> &V, Eigen::Matrix<double, 3, saltro::limits::MAX_LENGTH_TRAJ> &B, Eigen::Matrix<double, 3, saltro::limits::MAX_LENGTH_TRAJ> &S, Eigen::Matrix<double, 1, saltro::limits::MAX_LENGTH_TRAJ> &rho)

Generate orbital state and environment data along a trajectory.

High-level driver that propagates a spacecraft orbit and evaluates environmental quantities (magnetic field, Sun vector, and atmospheric density) at each requested time sample. The function dispatches to the selected orbit, magnetic, solar, and density models based on the integer selector flags.

Given initial position \(\mathbf{r}_0\) and velocity \(\mathbf{v}_0\), the spacecraft state is propagated to each time sample \(t_k\):

\[ \bigl(\mathbf{R}_k, \mathbf{V}_k\bigr) = \Phi_{\text{orbit}}\!\left(\mathbf{r}_0, \mathbf{v}_0, t_k\right) \]

At each propagated state, the following quantities are evaluated:

• Magnetic field:

  \[ \mathbf{B}_k = \mathbf{B}_{\text{model}}\!\left(\mathbf{R}_k, t_k\right) \]

• Spacecraft-to-Sun vector:

  \[ \mathbf{S}_k = \mathbf{r}_{\odot}(t_k) - \mathbf{R}_k \]

• Atmospheric density:

  \[ \rho_k = \rho_{\text{model}}\!\left(\mathbf{R}_k, \mathbf{S}_k\right) \]

The results are written column-wise:

\[ \mathbf{R} = \begin{bmatrix} \mathbf{R}_0 & \cdots & \mathbf{R}_{N-1} \end{bmatrix},\quad \mathbf{V} = \begin{bmatrix} \mathbf{V}_0 & \cdots & \mathbf{V}_{N-1} \end{bmatrix},\quad \mathbf{B} = \begin{bmatrix} \mathbf{B}_0 & \cdots & \mathbf{B}_{N-1} \end{bmatrix},\quad \mathbf{S} = \begin{bmatrix} \mathbf{S}_0 & \cdots & \mathbf{S}_{N-1} \end{bmatrix} \]

and density as:

\[ \boldsymbol{\rho} = \begin{bmatrix} \rho_0 & \cdots & \rho_{N-1} \end{bmatrix} \]

Supported model identifiers:

• Orbit model:

  • 0 → Keplerian two-body propagation

  • 1 → J2 perturbation with RK4 integration

• Magnetic model:

  • 0 → Tilted dipole

  • 1 → IGRF-8

  • 2 → IGRF-13

• Sun model:

  • 0 → NOAA

  • 1 → NREL SPA

• Eclipse model:

  • 0 → Cylindrical shadow

• Density model:

  • 0 → Harris–Priester

This function performs input validation and orchestrates the individual model calls. Each model computation is applied sequentially along the trajectory samples.

Parameters:

• r0 – Initial position vector in an inertial frame (meters).

• v0 – Initial velocity vector in an inertial frame (m/s).

• jtime – Julian centuries corresponding to each trajectory sample.

• jtime_length – Number of valid trajectory samples.

• orbit_model – Orbit model selector.

• magnetic_model – Magnetic field model selector.

• sun_model – Solar position model selector.

• eclipse_model – Eclipse shadow model selector.

• density_model – Atmospheric density model selector.

• R – Output propagated position vectors (meters), column-wise.

• V – Output propagated velocity vectors (m/s), column-wise.

• B – Output magnetic field vectors (Tesla), column-wise.

• S – Output spacecraft-to-Sun vectors (meters), column-wise.

• rho – Output atmospheric density values (kg/m³).

Returns:

True if all model computations succeed, false if any stage fails.