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Ground Stations

Ground-based tracking and observation support.

Quick Example

import lox_space as lox

# Define a ground station
gs = lox.GroundLocation(
    origin=lox.Origin("Earth"),
    longitude=0.0 * lox.rad,    # Greenwich
    latitude=51.5 * lox.deg,    # ~51.5° N
    altitude=0.0 * lox.km,
)

# Calculate observables for a spacecraft state
obs = gs.observables(state)
print(f"Azimuth: {obs.azimuth().to_degrees():.2f} deg")
print(f"Elevation: {obs.elevation().to_degrees():.2f} deg")
print(f"Range: {obs.range().to_kilometers():.1f} km")

# Define elevation mask
mask = lox.ElevationMask.fixed(5 * lox.deg)

# Or variable mask based on azimuth
import numpy as np
azimuth = np.linspace(0, 2*np.pi, 36)
elevation = np.full(36, 0.1)  # radians
mask = lox.ElevationMask.variable(azimuth, elevation)

GroundLocation

Represents a location on the surface of a celestial body.

Parameters:

  • origin

    –

    The central body (e.g., Earth, Moon).

  • longitude

    –

    Geodetic longitude as Angle.

  • latitude

    –

    Geodetic latitude as Angle.

  • altitude

    –

    Altitude above the reference ellipsoid as Distance.

Examples:

>>> darmstadt = lox.GroundLocation(
...     lox.Origin("Earth"),
...     longitude=8.6512 * lox.deg,
...     latitude=49.8728 * lox.deg,
...     altitude=0.108 * lox.km,
... )

Methods:

  • altitude –

    Return the altitude above the reference ellipsoid.

  • latitude –

    Return the geodetic latitude.

  • longitude –

    Return the geodetic longitude.

  • observables –

    Compute observables to a target state.

  • origin –

    Return the central body (origin).

  • rotation_to_topocentric –

    Return the rotation matrix from body-fixed to topocentric frame.

altitude 

altitude() -> Distance

Return the altitude above the reference ellipsoid.

latitude 

latitude() -> Angle

Return the geodetic latitude.

longitude 

longitude() -> Angle

Return the geodetic longitude.

observables 

observables(
    state: Cartesian,
    provider: EOPProvider | None = None,
    frame: str | Frame | None = None,
) -> Observables

Compute observables to a target state.

origin 

origin() -> Origin

Return the central body (origin).

rotation_to_topocentric 

rotation_to_topocentric() -> ndarray

Return the rotation matrix from body-fixed to topocentric frame.

ElevationMask

Defines elevation constraints for visibility analysis.

An elevation mask specifies the minimum elevation angle required for visibility at different azimuth angles. Can be either fixed (constant) or variable (azimuth-dependent).

Parameters:

  • azimuth

    –

    Array of azimuth angles in radians (for variable mask).

  • elevation

    –

    Array of minimum elevations in radians (for variable mask).

  • min_elevation

    –

    Fixed minimum elevation as Angle.

Examples:

>>> # Fixed elevation mask (5 degrees)
>>> mask = lox.ElevationMask.fixed(5.0 * lox.deg)

>>> # Variable mask based on terrain
>>> mask = lox.ElevationMask.variable(azimuth, elevation)

Methods:

  • azimuth –

    Return the azimuth array (for variable masks only).

  • elevation –

    Return the elevation array (for variable masks only).

  • fixed –

    Create a fixed elevation mask with constant minimum elevation.

  • fixed_elevation –

    Return the fixed elevation value (for fixed masks only).

  • min_elevation –

    Return the minimum elevation at the given azimuth.

  • variable –

    Create a variable elevation mask from azimuth-dependent data.

azimuth 

azimuth() -> list[float] | None

Return the azimuth array (for variable masks only).

elevation 

elevation() -> list[float] | None

Return the elevation array (for variable masks only).

fixed classmethod 

fixed(min_elevation: Angle) -> Self

Create a fixed elevation mask with constant minimum elevation.

fixed_elevation 

fixed_elevation() -> Angle | None

Return the fixed elevation value (for fixed masks only).

min_elevation 

min_elevation(azimuth: Angle) -> Angle

Return the minimum elevation at the given azimuth.

variable classmethod 

variable(azimuth: ndarray, elevation: ndarray) -> Self

Create a variable elevation mask from azimuth-dependent data.

Observables

Observation data from a ground station to a target.

Parameters:

  • azimuth

    –

    Azimuth angle as Angle.

  • elevation

    –

    Elevation angle as Angle.

  • range

    –

    Distance to target as Distance.

  • range_rate

    –

    Rate of change of range as Velocity.

Methods:

  • azimuth –

    Return the azimuth angle.

  • elevation –

    Return the elevation angle.

  • range –

    Return the range (distance).

  • range_rate –

    Return the range rate.

azimuth 

azimuth() -> Angle

Return the azimuth angle.

elevation 

elevation() -> Angle

Return the elevation angle.

range 

range() -> Distance

Return the range (distance).

range_rate 

range_rate() -> Velocity

Return the range rate.

Pass

Represents a visibility pass between a ground station and spacecraft.

A Pass contains the visibility interval (start and end times) along with observables computed at regular intervals throughout the pass.

Methods:

  • interpolate –

    Interpolate observables at a specific time within the pass.

  • interval –

    Return the visibility interval for this pass.

  • observables –

    Return the observables at each time sample.

  • times –

    Return the time samples during this pass.

interpolate 

interpolate(time: Time) -> Observables | None

Interpolate observables at a specific time within the pass.

interval 

interval() -> Interval

Return the visibility interval for this pass.

observables 

observables() -> list[Observables]

Return the observables at each time sample.

times 

times() -> list[Time]

Return the time samples during this pass.