myrocketsimulator 1.2.0

MyRocketSimulator is a Python package designed to simulate spacecrafts launching from Earth and orbiting around it or flying to the Moon.

Welcome to MyRocketSimulator!

MyRocketSimulator is a Python library for spacecraft orbit propagation around the Earth and missions towards and around the Moon. It provides the simulation environment for the author’s plan to replicate the complete trajectory of Apollo 11, from launch to splashdown. Necessary parts for such an undertaking a continuously added to MRS.

The simulator relies on a high-fidelity propagator that includes all relevant perturbating forces, such as drag, SRP, gravity with spherical harmonics and third body gravity. A published in-depth comparison with GMAT proved its accuracy for Earth orbiting spacecrafts. Download the paper Spacecraft Orbit Propagation with the MyRocketSimulator Python Package.

An early, non-published release of MRS was used to perform a preliminary flight simulation and analysis of the Moon-bound Artemis I mission. Download the paper Preliminary Launch Trajectory Simulation for Artemis I with the Space Launch System.

MRS 1.2 was used to recreate the actual launch trajectory of Artemis I by optimizing control parameters, aiming to reach a known statevector of the spacecraft some time after trans-lunar injection. Read the paper Artemis I Launch Trajectory Reconstruction with the MyRocketSimulator Python Package.

Relevant features of MRS 1.2:

• Multi-segment simulations providing distinct force configurations and delta-v maneuvers.
• Earth and Moon gravity with spherical harmonics using pyshtools.
• Solid tides for Earth and Moon.
• Third bodies (Sun, Venus, Mars, Jupiter, Moon).
• Precise ephemeris and coordinate transformations through Skyfield.
• Atmospheric modelling with PyNRLMSISE-00.
• DOP853 integration from SciPy.
• Data frame export, including more than 60 run-time variables.
• Import of external state vectors for 1:1 trajectory comparison.
• Spacecraft modelling based on different parts with individual stages and engines.
• Attitude control in different frames, such as local ENU, launchsite ENU, VNB, relative to inertial and Earth-fixed velocity.
• Delta-v maneuvers in different frames.
• Pre-configured visualizations.

The typical workflow of MRS has three steps:

• Define the mission settings, e.g. by writing your own mission file or editing a provided file.
• Run the propagation.
• Add required data and export the data frame for further use.

Exemplary visualization of flight with two delta-v maneuvers in order to raise the spacecraft's altitude:

Installation

PyPI

MRS can be automatically installed trough its release on PyPI (Link). Simply execute the following command:

pip install myrocketsimulator

Github

The MRS library can be manually downloaded from Gibthub (Link). After downloading the repository, simply execute the following command in its top folder:

pip install .

Getting started

After installation, you are ready to start with your first simulation. The following code performs a 24-hour propagation of the ISS, using the included MRS default mission. Please note that Skyfield and spaceweather will require an internet connection to download relevant data, such as ephemeris files.

# import MRS libraries
from myrocketsimulator import MRSlib, MRSvislib

# make MRSMission object with the default MRS mission
MRSdemo0mission = MRSlib.MRSmission('defaultMRSmission')

# run mission
MRSdemo0mission.run_mission()

# add latitude and longitude data to the data frame 
MRSdemo0mission.expand_DFname(['EarthLLA'])

# make MRSvislib object with the performed mission
MRSdemo0viewer = MRSvislib.MRSviewer(MRSdemo0mission)

# show ground track
MRSdemo0viewer.plot_GroundtrackEarth()

The console output will be:

MRS:		Using default mission.
MRS:		Loading mission object 'defaultMRSmission'.
MRS:		Mission 'Default MRS Mission (ISS)' loaded.
MRS:		Checking mission data validity.
MRS:		Loading Default MRS spacecraft (ISS) as static spacecraft.
MRS:		Mission data valid.
MRS:		Running mission Default MRS Mission (ISS).
MRS:		Processing mission segment 0.
MRS:		Mission ended. Processing time: 1.301 seconds.
MRS:		Adding Earth LLA to dataframe.
MRSviewer:	Loading dataframe of mission Default MRS Mission Update.

The ground track will be shown as a figure:

Demo missions

The github repository contains demo missions that demonstrate different features of MyRocketSimulator. They can be used as template for your own missions.

• MRSexample0: simple propagation of the ISS (see Getting started)
• MRSexample1: satellite propagation and GMAT comparison
• MRSexample2: high accurate propagation with GMAT orbital element comparison
• MRSexample3: two delta-v maneuvers to perform a Hohmann transfer

Demo missions including features from MRS 1.2 such as spacecraft modelling and guidance to simulate actual launch trajectories will be added in future.

Documentation

MRS does currently not provide its own help function or further documentation, but can be easily learned by using the following resources:

• Demo missions.
• The publication Spacecraft Orbit Propagation with the MyRocketSimulator Python Package contains a good summary of MRS 1.0 features. More features have been added since its publication and may be described in later publications.
• Read the code of the MRS default mission (myrocketsimulator/data/defaultMRSmission.py).
• Read the code of the Artemis I launch trajectory simulation.
• Print the docstrings of all methods used in the demo mission, e.g. through:

print(MRSlib.MRSmission.load_mission.__doc__)

• Read the code of MRSlib's exportDataframes() to learn what data can be added to the data frame.
• Send your questions to [e-mail].
• Follow for updates on X: www.twitter.com/myrocketsim.