Editor: CelesTrak API Integration

This guide provides an overview of how the CelesTrak can be integrated to initialize orbits from the CelesTrak database. CelesTrak is an online resource of orbit data for objects in the Low Earth Orbit (LEO). Several Blueprint functions have been provided to cover generic and specific API calls. The Demo_CelesTrak demo in Nominal Editor is referenced in this guide and is a provided example of using one of the CelesTrak functions to initialize an orbit from the database.

Kelso, T.S. (2023). CelesTrak: A website for satellite orbit data and resources accessible via HTTP requests. Retrieved from https://celestrak.org/

Warning

The functionality for CelesTrak depends on a valid Internet connection. As such, the functionality of this feature may depend on the environment in which Nominal Editor is being run. Cloud deployments, for example, may not run CelesTrak functions.

CelesTrak Functions

The base CelesTrak function, CelesTrak Query, enables calling either the GP Query or Sup GP Query from the CelesTrak Website. The CelesTrak Query provides an orbital data response in one of the following formats:

TLE or 3LE: Two or Three-line element sets.
2LE: Two-line element sets (no satellite name on Line 0).
XML: OMM XML format, including all mandatory elements.
KVN: OMM KVN format, including all mandatory elements.
JSON: OMM keywords for all GP elements in JSON format.
JSON-PRETTY: OMM keywords for all GP elements in JSON pretty-print format.
CSV: OMM keywords for all GP elements in CSV format.

Note

A Timeout parameter is included in all CelesTrak Queries, as Unreal is a single-threaded application and CelesTrak Queries may take several seconds. If an Internet connection is lost, then the timeout will force a cancellation of the query.

The next tier of CelesTrak functions is preconfigured to return the data in the two-line element (TLE) format whilst allowing for any CelesTrak query.

If users want a specific CelesTrak object, both versions of the CelesTrak Queryfunction can be configured to search based onNORAD Catalog Number or International Designator. Additional options are also provided based on CelesTrak’s additional options.

The final tier of CelesTrak Functions are custom functions that are entirely preconfigured. Aside from the Internal Space Station (ISS) Catalog Number Helper function, these functions can return a significant number of TLEs that may hinder simulation performance.

Configuring the Simulation

As the simulation breaks from the usual structure of Nominal Editor simulations, the first step is to get the TLE data to be used. In the case of the referenced demo, the TLE data for Tracked Debris is used via the CelesTrak Query Debris (TLE) function.

The TLE data is then sorted by the EPOCH information so that the oldest data is first. The number of entries used in the demo is also capped. The simulation then spawns a spacecraft representing a piece of debirs, when the simulation reaches that epoch.

Simulation Result