Exporting orbits and space environment
Thermal Desktop offers several External Heating Environment types to define orbits and space environments for your spacecraft:
- Basic Orbit,
- Keplerian Orbit,
- Planetary Latitude, Longitude, Altitude List,
- Orbital Sun/Planet/Radius Vector List,
- Free Molecular Heating using a Vector List,
- Free Molecular Heating with Reference Orbit.
Simcenter 3D Space Systems Thermal provides several entities for defining orbits and space environments:
- Orbit modeling object,
- Orbital Heating simulation object,
- Solar Heating Space simulation object,
- Free Molecular Heating simulation object.
Thermal Model Exchanger does not support Free Molecular Heating using a Vector List and Free Molecular Heating with Reference Orbit types of External Heating Environment.
Orbit
In Thermal Desktop, all the orbit characteristics and parameters are defined within the Orbit dialog box with several tabs. Note that the first tab changes with the type of orbit you select, see the Orbit Parameters (Basic Orbit, Keplerian Orbit and Vector Input tabs) section below for more details.
The Simcenter 3D Orbit modeling object specifies the planet, orbit type and parameters and the spacecraft attitude that are used by the Orbital Heating simulation object to compute the heat transfer between the spacecraft and the space environment. This simulation object specifies the parts of the model that are affected by the orbit, and the calculation method used to compute the radiation with the environment.
Supported orbit characteristics
External Heating Environment types
Thermal Model Exchanger only supports the Basic Orbit, Keplerian Orbit and Orbital Sun/Planet/Radius Vector List Thermal Desktop Orbit type of External Heating Environment. For the orbit types, Simcenter 3D offers a larger list of orbits than Thermal Desktop, which are all special cases of the Thermal Desktop Keplerian Orbit. For each Thermal Desktop external heating environment type that Thermal Model Exchanger converts, the following table lists the corresponding Simcenter 3D orbits type.
| Thermal Desktop External Heating Environments | Simcenter 3D Orbits |
| Basic Orbit | Beta-Angle |
| Keplerian Orbit | Classical |
| Orbital Sun/Planet/Radius Vector List | Sun Planet Vectors |
Orientation
When you define the spacecraft orientation in Thermal Desktop, you can only select a predefined axis while in Simcenter 3D you can specify any vector. Thermal Model Exchanger reproduces the spacecraft orientation specified on the Pointing, Additional Constraint, and Additional Rotations groups in the Thermal Desktop Orbit dialog box to fill the Spacecraft Attitude page in the Simcenter 3D Orbit dialog box. Thermal Model Exchanger does not support the Align to Celestial Coordinate System of the Orientation Override group.
Planetary Data, Solar, Albedo and IR Planetshine tabs
Thermal Model Exchanger uses the information specified on the Planetary Data, Solar, Albedo and IR Planetshine tabs in the Thermal Desktop Orbit dialog box to fill the options on the Simcenter 3D Sun Planet Characteristics page in the Orbit modeling object dialog box.
Basic Orbit, Keplerian Orbit and Vector Input tabs
Because the Thermal Desktop Basic Orbit and the Simcenter 3D Beta Angle orbit are equivalent, Thermal Model Exchanger does not apply specific operations during the import process.
For the Thermal Desktop Keplerian Orbit, Thermal Model Exchanger uses the parameters specified in the Keplerian Orbit tab to fill the Orbit Parameters page in the Simcenter 3D Orbit modeling object.
For the Thermal Desktop Orbital Sun/Planet/Radius Vector List type of External Heating Environment, Thermal Model Exchanger uses the data specified in the Vector Input tab to create a Simcenter 3D table field for specifying the orbit parameters of the Simcenter 3D Sun Planet Vectors orbit type. Thermal Model Exchanger converts the Ratio of distance from Earth's center to Earth's radius parameter to the spacecraft's altitude parameters during the import process.
Positions tab
Thermal Model Exchanger supports full and partial orbits.
For orbits that use Use Equal Increments option, Thermal Model Exchanger enables the Number of Intervals angular interval method on the Calculation Position page in the Simcenter 3D Orbit dialog box.
For orbits that use Use Positions option, Thermal Model Exchanger enables the Angular Positions angular interval method on the Calculation Position page in the Simcenter 3D Orbit dialog box.