Description

This repository provides examples for orbit determination based on laser ranging data, in the form of Jupyter Notebooks.

The open-source orbital dynamics library Orekit (https://www.orekit.org/) is used for all calculations, and in particular the Python wrapper developed by @petrushy: https://gitlab.orekit.org/orekit-labs/python-wrapper

Installation

Notes on Orekit versions

The Orekit example notebooks are based on Orekit 12.1.1 (previously 10.2 IIRC). The Orekit version is frozen in requirements.txt to avoid breaking changes due to new Orekit major releases.

Prerequisites

• Python 3.7+

Create a venv and install dependencies

Create a venv:

python -m venv .venv

Enter the venv:

source .venv/bin/activate

Install the dependencies:

python -m pip install -r requirements.txt

Use

• Enter the venv: source .venv/bin/activate
• Start Jupyter Lab: jupyter lab
• Jupyter Lab should pop up in your browser at the URL http://localhost:8888

Or just open the notebook in VSCode and select the .venv as kernel.

Updating data files

Orekit data

Laser ranging station coordinates

The station coordinates files (position&velocity) are updated from time to time. Check out for files named with the format SLRF2020_POS+VEL_xxxxxx.snx on ftp://cddis.nasa.gov/slr/products/resource/

The newest eccentricities file is always renamed ecc_xyz.snx and is available at ftp://cddis.gsfc.nasa.gov/slr/slrocc/ecc_xyz.snx