orbdetpy 2.0.0

Introduction

This is orbdetpy, a library of Python and Java routines for orbit determination. It is a thin Python wrapper for our estimation tools and Orekit, which are both written in Java.

Features

The force model for orbit propagation currently includes:

1. EGM96 gravity field up to degree and order 360.
2. Earth solid tides due to the influence of the Sun and Moon.
3. FES 2004 ocean tide model up to degree and order 100.
4. The NRL MSISE-00 and simple exponential models for atmospheric drag.
5. Solar radiation pressure.
6. Third body perturbations from the Sun and Moon.

The measurement model supports range, range-rate, angles, and inertial Cartesian coordinates. Filtering is done with our Unscented Kalman Filter or Orekit's Extended Kalman Filter. Dynamic Model Compensation (DMC) can be used with either filter to estimate additional perturbing acclerations that result from unmodeled dynamics, maneuvers etc.

Installation

1. Install the Java Development Kit 8 (1.8) from http://openjdk.java.net/install/index.html. Set the JAVA_HOME environment variable to point to your JDK installation. The java executable must also be in your system path.

2. Install Python 3.7.0 or higher and run pip install orbdetpy to install orbdetpy and other package dependencies. If you wish to use the develop or other experimental branches from GitHub, git clone them and run pip install -e . from the top level orbdetpy folder.

3. Source code, example programs and data files can be downloaded from https://github.com/ut-astria/orbdetpy.

4. Update the astrodynamics data in orbdetpy/data periodically by running the following. You might need to do so as root on Unix-like systems.

   python -c "from orbdetpy.astro_data import update_data; update_data();"

5. Apache Maven 3+ is needed if you hack the Java code and need to rebuild the JAR files. Switch to the orbdetpy/ folder and run the following, where os_cpu_type is linux-x86_64, linux-x86_32, windows-x86_64, windows-x86_32, osx-x86_64, or osx-x86_32, depending on your CPU architecture and OS.

   mvn -e -Dos.detected.classifier=os_cpu_type package

   If you are on Intel/AMD 64-bit Linux the command-line simplifies to:

   mvn -e package

Examples

1. predict_passes.py : Predict satellite passes for ground stations or geographic regions using TLEs. Current elements may be obtained from sites such as http://www.celestrak.com.

2. propagate_tle.py : Propagate TLEs given by command-line arguments.

3. test_conversion.py : Test reference frame and other conversion functions.

4. test_estimation.py : Demonstrates measurement simulation and orbit determination functions.

5. test_interpolation.py : Interpolate state vectors.

Known Issues

1. In Microsoft Windows, you might receive warnings from the "Windows Defender Firewall" when you import orbdetpy. You can safely allow orbdetpy access to the network because this only involves a single TCP port on localhost.