ephemerista 0.1.0

Ephemerista is an open source (AGPLv3-licensed) Python library for space mission design and analysis with a focus on telecommunications and constellation design. The development of the first release of Ephemerista was funded by the European Space Agency (ESA).

Ephemerista is being maintained by the Libre Space Foundation.

Features

• Time scale and reference frame transformations
• Semi-analytical and numerical orbit propagation
• Event detection
• Spacecraft and ground asset modelling
• Communication systems modelling and link budgets analyses
• Constellation design and coverage analyses
• Web-based graphical user interface available at the LSF GitLab

Requirements

System Requirements

• Python 3.12 or higher
• Java Runtime Environment (JRE) 21 or higher (automatically installed via jdk4py)
• Maven (for building from source)

Python Dependencies

Core dependencies include:

• numpy ~1.26
• pandas ~2.1
• scipy ~1.14
• matplotlib 3.9.4
• pydantic ~2.8
• lox-space 0.1.0a23
• orekit_jpype ~12.1.1.0
• plotly ~5.22
• geopandas ~1.0.1

For a complete list of dependencies, see pyproject.toml.

Quickstart

Installation

Ephemerista is distributed on PyPI and can be installed via uv.

# Create and activate a new virtual environment (Optional)
uv venv
source .venv/bin/activate # On Linux and macOS
# .\.venv\Scripts\activate.ps1 # On Windows

# Install Ephemerista
uv pip install ephemerista

Obtain Required Data

Ephemerista requires the following data at runtime:

• Earth orientation parameters from the IERS: finals2000A.all.csv
• Planetary ephemerides in SPK format, e.g. de44s.bsp
• An Orekit data package: orekit-data-main.zip
  • Alternatively, the Orekit data can be installed as a Python package via pip, see here.

Initialise Ephemerista

Call the ephemerista.init function before using any other Ephemerista functionality and provide the paths to the required data files.

import ephemerista

EOP_PATH = ... # e.g. finals2000A.all.csv
SPK_PATH = ... # e.g. de440s.bsp
OREKIT_DATA_PATH = ... # e.g. orekit-data-main.zip

ephemerista.init(eop_path=EOP_PATH, spk_path=SPK_PATH, orekit_data=OREKIT_DATA_PATH)

If the Orekit data package was installed via package manager the orekit_data parameter can be omitted.

Use Ephemerista

Propagate the orbit of the ISS with Ephemerista.

import ephemerista
from ephemerista.propagators.sgp4 import SGP4
from ephemerista.time import TimeDelta

# Propgate the trajectory
iss_tle = """ISS (ZARYA)
1 25544U 98067A   24187.33936543 -.00002171  00000+0 -30369-4 0  9995
2 25544  51.6384 225.3932 0010337  32.2603  75.0138 15.49573527461367"""

propagator = SGP4(tle=iss_tle)
start_time = propagator.time
end_time = start_time + TimeDelta.from_hours(6)
times = start_time.trange(end_time, step=float(TimeDelta.from_minutes(1)))
trajectory = propagator.propagate(times)

For more information, visit Ephemerista's documentation.

Examples

Example Jupyter notebooks and data files are available in the examples/ directory. If you installed Ephemerista via pip, you can download the examples from:

• Browse online: GitLab examples directory
• Download all: See examples/README.md for download instructions

The examples include:

• Interactive Jupyter notebooks demonstrating all major features
• Pre-configured mission scenarios (lunar transfer, navigation, link budgets)
• Sample antenna patterns and geographic areas
• Complete workflows for visibility, coverage, and interference analysis

Development

Please refer to CONTRIBUTING.md.

License

ephemerista is distributed under the terms of the AGPLv3 license.