Orbit Visualiser

The Orbit Visualiser is a 2D Keplerian orbit visualisation tool for modelling the motion of a satellite around a central body, written in Python. The focus of this tool is on orbital geometry and satellite kinematics. Currently there is no simulation-based functionality.

Features

Orbits are modelled and visualised in the perifocal frame (the central body remains fixed at the origin of the coordinate frame), with the orbital geometry parametrised using:

• Eccentricity
• Radius of periapsis

The central body has a radius of 6738km and an adjustable gravitational parameter. The radius of periapsis has therefore been given a lower limit of 6739km (meaning that we are assuming this Earth sized body has no atmosphere, or at least that any atmosphere has no effect on orbital motion). The true anomaly of the orbiting satellite is also adjustable to evaluate the kinematic state at different orbital positions. Various orbital and kinematic quantities are calculated and displayed, including:

• Semi-major/minor axis
• Radius of apoapsis
• True anomaly of the asymptote (for parabolic and hyperbolic trajectories)
• Specific angular momentum
• Radial velocity
• Azimuthal velocity
• Escape velocity
• Hyperbolic excess velocity
• Time since periapsis

Notes on the physical model

The orbiting satellite is assumed to have negligible mass. All higher-order perturbations, such as atmospheric drag or oblateness, are ignored.

Potential future improvements

• Introduce argument of periapsis as an orbital geometry parameter
• Simulate orbital motion
• Expand orbital modelling to 3 dimensions
• Include perturbations into the model
• Expand modelling to R3BP or N-body system
• Visualise gravitational field

Requirements

• Python 3.8 or later
• Git (optional but recommended, for cloning the repository)

Python dependencies

• numpy
• matplotlib

These are also listed in the requirements.txt file.

How to use

Clone the repository:

git clone https://github.com/Phim226/orbit-visualiser.git

Navigate to project folder:

cd orbit-visualiser

Install dependencies:

pip install -r requirements.txt

Install the package locally (if you want to make changes include the -e option after "install" to make it an editable installation):

pip install .

Run the program:

python src/orbit_visualiser/main.py