UCL SGNL's Radiation Force Modelling Wiki

Radiation Force Modelling Pipeline

This wiki presents an overview of the process for generating a spacecraft radiation force model using the UCL method. The process begins with initial information gathering and extends to integration with advanced orbit propagation/determination tools, such as NASA JPL's GipsyX.

The initial phase of modeling involves gathering information on the spacecraft, either from open source infromation or from direct collaboration with spacecraft engineering teams.

The construction of the spacecraft model focuses on two critical aspects: the accurate representation of its geometry (shape, orientation, and size) and the precise characterization of material properties (which influence interaction with incident or exiting radiation). From this information, the model is written line-by-line in a text file, using geometric primitives. The process is detailed in the STC Manual . The process is iterative, and the utilization of the spacecraft visualizer is key for obtaining quick and frequent feedback during this phase.

Following the completion of the spacecraft model, the next step involves generating the radiation force model using SRP-TRR Classic (STC), a C++ program. STC takes the detailed spacecraft model and material properties to produce a set of files that constitute the radiation force model.

Due to the computation-intensive nature of this process, it is typically executed on the UCL Research Compute Cluster (Myriad).

Upon successful computation, the radiation force model is ready for testing in orbit propagation scenarios and can be integrated into other orbital analysis tools.

The following sections detail the specific roles of each code repository involved in this process. Click on the headers for access to the corresponding repositories. Please note that certain repositories require appropriate permissions for access.

• SpaceCraft Visualizer

  JavaScript-based spacecraft model visualizer. To set up and access the visualizer, follow these steps:

  1. Open the command prompt and change directory (cd) into the scviz directory.
  2. To set up a local HTTP server: python3 -m http.server
  3. Open a browser in the url bar: localhost:8000
  4. To access the visualiser, open viewer.html

• SRP-TRR Classic

  C++-based solar radiation pressure and thermal re-radiation calculations.

  1. Detailed instructions on how to build a radiation force model from Spacecraft geometry and material properties is extensively covered here: STC Manual (v5.07).
  2. Instructions for setting up the radiation force model computation on UCL's Myriad Research Compute Cluster remotely, transferring files, and running computations can be found in our Guide to Using SRP-TRR Classic on Myriad.

• Python Grid Utilities

  Resampling the grid files for use in simulations

  1. Download grid utils and create a new directory named after your mission inside the grid utils folder.
  2. Using WinSCP, copy the force model files from Myriad to your local machine into the newly created mission directory.
  3. Run the pad_sp_output.py script to pad the spiral points file, ensuring it is correctly formatted for the grid generation step.
  4. To create grid files, run the createBasShepardMultiple.py script with appropriate parameters for your mission. This will produce .BAS files in the surfer directory.
  5. Move the generated grid files to a dedicated directory within your mission folder and run the surfer6poleReplicate.py script to replicate the data for the poles.
  6. The final radiation force grid files are now ready for use.

• ODL22

  The 2022 version of our full-fidelity C++ orbit propagator.