satorbit 0.2.0

Satellite orbit tools: TLE propagation, SP3 parsing, and coordinate transformations

satorbit

Satellite orbit tools for Python: TLE propagation, SP3 parsing, and coordinate transformations.

Originally developed at KNMI (Royal Netherlands Meteorological Institute) as part of swxtools.

Installation

pip install satorbit

Features

• TLE handling: Query space-track.org, parse TLE data, and propagate orbits using SGP4
• SP3 parsing: Read SP3 precise orbit files into pandas DataFrames
• Coordinate transforms: Convert between ITRF, geodetic, GCRS, and Quasi-Dipole coordinates
• Keplerian mechanics: Simulate orbits with J2 perturbation effects

Usage

TLE Propagation

import pandas as pd
from satorbit import geodetic_orbit_from_tle

# Generate orbit positions for a satellite over a time range
times = pd.date_range("2024-01-01", "2024-01-02", freq="1min")
orbit = geodetic_orbit_from_tle(norad_id=25544, times=times)  # ISS
print(orbit[['lat', 'lon', 'height']])

SP3 File Parsing

from satorbit import sp3_to_itrf_df

df = sp3_to_itrf_df("orbit.sp3")
print(df[['x_itrf', 'y_itrf', 'z_itrf']])

Coordinate Transformations

from satorbit import itrf_to_geodetic, geodetic_to_qd

# Convert ITRF to geodetic coordinates
df_geo = itrf_to_geodetic(df_orbit)

# Convert to Quasi-Dipole magnetic coordinates
df_qd = geodetic_to_qd(df_geo)

Keplerian Orbit Simulation

import numpy as np
from satorbit import simulate_orbit, unperturbed_orbitalperiod

kepler = {
    "semimajoraxis": 7000,  # km
    "eccentricity": 0.001,
    "inclination": np.radians(98),
    "argumentofperigee": np.radians(90),
    "raan": np.radians(0),
    "initial_mean_anomaly": 0,
    "mu": 398600.4415,
    "re": 6378.1363,
    "j2": 1082.6357e-6
}

period = unperturbed_orbitalperiod(kepler)
times = np.linspace(0, period, 100)
orbit = simulate_orbit(kepler, times)

Configuration

For TLE queries from space-track.org, create ~/.spacetrackorg.txt:

[default]
username = your_username
password = your_password

License

Apache License 2.0 - see LICENSE

Acknowledgements

Developed with support from ESA through the Swarm Data Innovation and Science Cluster (Swarm DISC).