Editor: Environment Models
Description
This operator guide showcases how environment models can be added to a simulation In this guide, a basic simulation and a Magnetic Field Centered Dipole and Atmosphere Exponential environment models will be added to a blank level. The models can be viewed in use in the demo levels that come with the software.
Adding Environment Models
In the event graph, to add in an magnetosphere, the universe system will need to be fetched first. This can be found by calling Get UniverseSystem from the level blueprint. Once the system is added, multiple functions can be called. In this case, the Create Magnetic Field Centered Dipole can be called, which will create a magnetic field model around the Earth (or another body) with some basic parameters. The default parameters are correct for if the model existed around the Earth.
Note
The magnetic field-centered dipole model is an approximation of the Earth’s magnetic field. It is not completely accurate based on positions but it can be used as a benchmark for approximations and measurements. The WMM model is the more accurate magnetosphere model.
To add in an atmosphere, the Create Atmosphere Exponential function can be called, adding in an exponential atmosphere around the selected planet. The exponential atmosphere just assumes an atmospheric density that increases exponentially up from the surface of the planet.
Note
Similarly, the NRLMSIS model is the more accurate representation of the temperature and density variations around the Earth’s surface. This model is more computationally expensive to compute but is more accurate.
Once the play button is pressed, the Earth will be shown in the level (assuming no other components have been added). There will be no visible difference between not adding any of the models or adding the models to the Earth.
Advanced Models
Each of the magnetosphere and atmosphere models includes an advanced model which is calculated correctly and not an approximation. These models are the WMM and NRLMSIS models respectively. Unlike the approximation ones, these models are Earth-specific and cannot be used around other planets.
Warning
Only one atmosphere and one magnetosphere model can be added to a single planet at a time. If the WMM model is added, the centered-dipole model should not be added to the Earth.
Magnetic Field Example
Open up Demo_AttitudeFeedbackMTB. This demo uses the Magnetic Field Centered Dipole environment models that were added in this guide.
In the “TAM BODY MAGNETIC FIELD” graph on the right, the Magnetic Field that the Three-Axis Magnetometer (TAM) is reading is displayed. The messages on the left read zero as the values are so low the UI log is unable to display them.
Atmosphere Example
In Demo_EnvironmentPerturbations, it is set up with an Atmosphere and Drag effector by default. The spacecraft is affected by atmospheric drag with the Spacecraft’s SME decreasing over time.
