Computational manipulation with solid bodies is improving ISS aeroscience analyses.

Numerical simulations of plume impingement heating to the International Space Station (ISS) and its visiting vehicles require a specific way to represent the space station geometry in 3D. The tools that are used for plume impingement analyses at NASA’s Johnson Space Center — the Reaction Control System (RCS) Plume Model 3D (RPM3D) and Direct Simulation Monte Carlo (DSMC) Analysis Code (DAC) — need the analysis geometry to be in the form of a triangulated surface mesh and water-tight (no gaps or holes). Until recently, 3D geometries for such analyses had to be generated manually, took a long time, and used very-low-fidelity geometry components, and as a result, the aeroscience analyses in 3D were not very frequent.

Example of the ISS geometry configuration generated with the Space Station Modulator.
As the ISS geometry configuration is constantly changing with solar arrays tracking the Sun, thermal control system radiators positioned at different angles to better reject the waste heat, visiting vehicles attached to various ISS docking ports, and even some ISS modules and components moved around the station’s exterior, the need for a capability to quickly put together analysis-specific ISS geometry configurations was obvious.

The Space Station Modulator (SSM) computer model includes both the geometry components in the form of water-tight triangulated surface meshes and a suite of computer programs to perform manipulations with those components. By treating the geometry components as building blocks, the SSM puts together an analysis-specific configuration of the ISS. The main objective for the SSM development was to save time and minimize human error.

The SSM process takes less than 10 minutes, and consists of the following three main steps. First, the user creates a “pick list” where the geometry components needed for the analysis are selected. Next, the user prescribes the ISS solar arrays and radiators to be positioned at the required angles. And finally, the user specifies which visiting vehicles are going to be attached to which ports of the ISS.

Once the ISS configuration is ready, all geometry components may be written into a single geometry file that goes directly into the analysis. For convenience of post-processing the results, the SSM allows for distinguishing the individual components of the ISS.

The SSM was coded in Perl and Fortran. The triangulated surface meshes of the ISS and visiting vehicles were made using commercially available software package Star-CCM+ and were based on the CAD models available from NASA’s ISS Program.

This work was done by Max Larin of Jacobs Technology for Johnson Space Center. MSC-25779-1