opengnc.edl package

Module contents

Entry, Descent, and Landing (EDL) dynamics and utilities.

opengnc.edl.aerocapture_guidance(state: ndarray, target_apoapsis: float, cd: float, area: float, mass: float, planet_params: dict[str, float], rho_model: Any, cl: float = 0.0) → float

Predictive-Corrector Aerocapture Guidance.

Determines the required bank angle to achieve a target exit apoapsis by numerically integrating internal trajectories.

Parameters:

• state (np.ndarray) – Current spacecraft state $[r, v]$.

• target_apoapsis (float) – Desired apoapsis altitude after atmospheric exit (m).

• cd (float) – Vehicle ballistic parameters.

• area (float) – Vehicle ballistic parameters.

• mass (float) – Vehicle ballistic parameters.

• planet_params (Dict[str, float]) – Dictionary containing ‘mu’ and ‘r_planet’.

• rho_model (Any) – Atmospheric density model.

• cl (float, optional) – Lift coefficient. Defaults to 0 (ballistic).

Returns:

Optimized bank angle (rad).

Return type:

float

opengnc.edl.ballistic_entry_dynamics(t: float, state: ndarray, cd: float, area: float, mass: float, mu: float = 398600000000000.0, r_planet: float = 6371000.0, rho_model: Any | None = None) → ndarray

Ballistic Atmospheric Entry Dynamics (3-DOF).

Calculates the ECI state derivative for a non-lifting entry vehicle subject to spherical gravity and aerodynamic drag.

Parameters:

• t (float) – Elapsed time (s).

• state (np.ndarray) – ECI State vector $[x, y, z, v_x, v_y, v_z]$ (m, m/s).

• cd (float) – Drag coefficient.

• area (float) – Reference aerodynamic area ($m^2$).

• mass (float) – Vehicle mass (kg).

• mu (float, optional) – Gravitational parameter ($m^3/s^2$).

• r_planet (float, optional) – Planetary reference radius (m).

• rho_model (Optional[Any]) – Atmospheric density model providing get_density(r, jd).

Returns:

State derivative $[dot{r}, dot{v}]$ (m/s, $m/s^2$).

Return type:

np.ndarray

opengnc.edl.calculate_g_load(acc_vec: ndarray) → float

Calculate instantaneous G-load.

Parameters:

acc_vec (np.ndarray) – Net non-gravitational acceleration vector ($m/s^2$).

Returns:

Load in Earth g-units.

Return type:

float

opengnc.edl.hazard_avoidance(r: ndarray, v: ndarray, hazards: list[ndarray], safety_margin: float = 50.0) → ndarray

Reactive Hazard Avoidance Maneuver logic.

Parameters:

• r (np.ndarray) – Current spacecraft landing state.

• v (np.ndarray) – Current spacecraft landing state.

• hazards (List[np.ndarray]) – Coordinates of detected obstacles.

• safety_margin (float, optional) – Minimum separation distance (m).

Returns:

Correction $Delta V$ vector (m/s).

Return type:

np.ndarray

opengnc.edl.lifting_entry_dynamics(t: float, state: ndarray, cl: float, cd: float, bank_angle: float, area: float, mass: float, mu: float = 398600000000000.0, r_planet: float = 6371000.0, rho_model: Any | None = None) → ndarray

Lifting Atmospheric Entry Dynamics with Bank Angle Modulation.

Calculates the ECI state derivative for a vehicle with non-zero Lift-over-Drag (L/D) ratios.

Parameters:

• t (float) – Elapsed time (s).

• state (np.ndarray) – ECI State vector (m, m/s).

• cl (float) – Lift and Drag coefficients.

• cd (float) – Lift and Drag coefficients.

• bank_angle (float) – Rotation of the lift vector about the velocity vector (rad).

• area (float) – Reference area ($m^2$).

• mass (float) – Mass (kg).

• mu (float) – Planetary parameters.

• r_planet (float) – Planetary parameters.

• rho_model (Optional[Any]) – Density model.

Returns:

State derivative.

Return type:

np.ndarray

opengnc.edl.sutton_grave_heating(rho: float, v: float, rn: float) → float

Stagnation Point Heat Flux via Sutton-Grave Correlation.

Estimates the convective heat transfer at the vehicle nose during hypersonic atmospheric entry. Equation: $dot{q} = k sqrt{rho / r_n} v^3$.

Parameters:

• rho (float) – Atmospheric density ($kg/m^3$).

• v (float) – Relative velocity (m/s).

• rn (float) – Nose/Stagnation region radius (m).

Returns:

Stagnation heat flux ($W/m^2$).

Return type:

float