Example UnrealEngine5 space-track.com REST api http client.

This project requires the MaxQ Spaceflight Toolkit plugin from the Unreal Engine Marketplace.
https://www.unrealengine.com/marketplace/en-US/product/146e96d801ed4d8d930b41bfeca53733

Tutorial Link:
Call a SatCat REST API from Unreal Engine on gameDevTricks.com
ASAT Code Tutorial 4: Call a SatCat REST API from Unreal Engine 5 on stupidRocketTricks.com

Note: This is a post is part of a multi-part series.

Today, we're going to use Unreal Engine's HTTP and JSON modules to create an interesting little visualization.

Along the way we're going to learn:

• How to send HTTP requests from within Unreal Engine
• How to parse a server's response (JSON)
• How to query a "Satellite Catalog" database operated by the U.S. Strategic Command
• How to get a list of active space debris objects associated with space weapons testing (with orbital data)
• How to compute a position from orbital data
• Where to find test data, and how to switch over to live data from the U.S. Strategic Command servers

You may have heard about a recent Russian Anti-Satellite (ASAT) test that created a bevvy of space debris.

Early in the morning of November 15, Moscow time, a Russian missile blasted a Russian satellite to smithereens. The destroyed satellite, Kosmos-1408, had been in orbit for nearly four decades. With at least 1,500 trackable pieces, and countless more too small for detection, the remains of Kosmos-1408 pose a threat to other objects in orbit. The destruction itself caused astronauts and cosmonauts aboard the International Space Station to shelter in space. It also risked harm to China’s taikonauts aboard the Tiangong space station.
This week’s destroyed Russian satellite created even more dangerous space debris
BY KELSEY D. ATHERTON, Popular Science

A Satellite Catalog (SatCat) contains information about objects in Earth's orbit. We can query a SatCat for orbital debris created by the Russian Anti-Satellite "test". While we're at it, we'll include debris from another destructive test, done by China in 2007. There have been other anti-satellite tests, but very little remains debris in orbit aside from these two events.

We'll get the debris object data from the REST API of a SatCat operated by the U.S. Strategic Command: Space-Track.org

If it sounds a bit serious, it is.

Air Force Maj. Gen. David D. Thompson, U.S. Strategic Command’s director of plans and policy at Offutt Air Force Base, Nebraska, said the release of new high-quality positional information on space debris of an unknown origin will help owner-operators better protect their satellites from these objects and ultimately create less space debris.
“We run a predictive program that shows where the objects are, where they will be in the future, and the potential for these objects to run into each other,” Thompson said.
Officials Expand Space-tracking Website
U.S. Department of Defense

If you adhere to the User Agreement you can obtain credentials to query the SatCat. You'll need a Space-Track.org username and password here shortly, fyi.

The app we build here will display a 3D map of Earth, update debris positions in real time, and let the user use the mouse to orbit and zoom the camera.

If you simply clone the repository and attempt to build it, you'll get a build error (By Design).

C:\git\gamedevtricks\ASATDebrisVisualization\DebrisCloud\Source\DebrisCloud.Target.cs(43,34): error CS0103: The name 'CSpice_Library' does not exist in the current context
ERROR: Expecting to find a type to be declared in a target rules named 'DebrisCloudTarget'.  This type must derive from the 'TargetRules' type defined by Unreal Build Tool.

This happens because MaxQ is not committed to the repository. One easy solution is to clone the MaxQ repository separately, and then add a symbolic link that maps the appropriate plugins subdirectory to the example application.

MaxQ GitHub page

Command prompt commands that create the appropriate directory, clone the required projects, and create the necessary symbolic link (on Windows):

mkdir c:\git\gamedevtricks\
cd /D c:\git\gamedevtricks\

rem - clone example project from github
git clone https://github.com/gamergenic/ASATDebrisVisualization.git

rem - clone the MaxQ dependency
git clone https://github.com/Gamergenic1/MaxQ.git

rem - create a directory junction in the sample project for MaxQ
mkdir ASATDebrisVisualization\DebrisCloud\Plugins
mklink /J ASATDebrisVisualization\DebrisCloud\Plugins\MaxQ MaxQ\Plugins\MaxQ

Junction created for ASATDebrisVisualization\DebrisCloud\Plugins\MaxQ <<===>> MaxQ\Plugins\MaxQ

Once you have the complete set of source code in place, generate the visual studio project files:

Now you can build the project's Unreal Engine Editor from the VS .sln.

Hit Control+Shift+B to build the editor, and you should have a successful build.

1>Building DebrisCloudEditor...
...
1>Total execution time: 50.60 seconds
========== Build: 1 succeeded, 0 failed, 0 up-to-date, 1 skipped ==========

You can now launch the Project's Unreal Engine editor via the F5 key, which starts a debug session with the Editor Application.

Once the Editor is launched you can click the 'Play' button, and see what happens.

If all goes well, the Unreal Engine Output window will indicate an http request was sent, and a response received:

LogTemp: Space-Track request: https://gamedevtricks.com/post/call-satcat-rest-api-from-ue-http/fengyun-1c-remaining.json; content:TEST_CONTENT
LogTemp: Space-Track request: https://gamedevtricks.com/post/call-satcat-rest-api-from-ue-http/cosmos-1408-remaining.json; content:TEST_CONTENT
LogTemp: Space-Track response: [
    {
        "CCSDS_OMM_VERS": "2.0",
        "COMMENT": "

And, you should be treated to a 3D display of earth and the debris fields from two Anti-Satellite weapons tests.

2007 Chinese anti-satellite missile test: Fengyun 1C
2021 Russian anti-satellite missile test: Kosmos 1408

The visualization you're viewing, though, is utilizing "stale" test data as opposed to live data from a SatCat.

Live data is available from Space-Track.org, a SatCat. Note, however, Space-Track.org is a service developed to serve satellite operators, who make use of its telemetry to avoid collisions with debris, etc. It's not for us nosey tinkering gamedevs, so tread lightly.

Space-Track.org is a site that shares space situational awareness services with satellite operators, academia, and other interested entities.

The user agreement is here:
https://www.space-track.org/documentation#user_agree

User Agreement
Please read the following terms and conditions of the User Agreement carefully! This website permits access to U.S. Government space situational awareness information to approved users only. To obtain access, all users must abide by the following terms and conditions:
The User agrees not to transfer any data or technical information received from this website, or other U.S. Government source, including the analysis of data, to any other entity without prior express approval. See, 10 USC 2274(c)(2).
...

With great power comes great responsibility... The API Query Builder tool allows users a great amount of power and flexibility in creating queries. Your space-track account may be suspended if you violate the usage policy by querying data too often or by running queries that negatively impact the performance of the website. Repeat offenders may have their account suspended permanently.

info
Using the service as a target for a non-trivial volume of end users is against the User Agreement and will get you in trouble with Uncle Sam. To that end, I've provided two sample files you can test your code against:
https://gamedevtricks.com/post/call-satcat-rest-api-from-ue-http/fengyun-1c-remaining.json
https://gamedevtricks.com/post/call-satcat-rest-api-from-ue-http/cosmos-1408-remaining.json
These are the test files the GitHub app uses by default.

The JSON response data format you'll receive from Space-Track.org.

[
    {
        "CCSDS_OMM_VERS": "2.0",
        "COMMENT": "GENERATED VIA SPACE-TRACK.ORG API",
        "CREATION_DATE": "2004-08-16T23:24:14",
        "ORIGINATOR": "18 SPCS",
        "OBJECT_NAME": "USA 19",
        "OBJECT_ID": "1986-069A",
        "CENTER_NAME": "EARTH",
        "REF_FRAME": "TEME",
        "TIME_SYSTEM": "UTC",
        "MEAN_ELEMENT_THEORY": "SGP4",
        "EPOCH": "1986-09-25T09:25:10.253855",
        "MEAN_MOTION": "16.08291950",
        "ECCENTRICITY": "0.01118730",
        "INCLINATION": "39.0531",
        "RA_OF_ASC_NODE": "276.4305",
        "ARG_OF_PERICENTER": "171.4053",
        "MEAN_ANOMALY": "189.5525",
        "EPHEMERIS_TYPE": "0",
        "CLASSIFICATION_TYPE": "U",
        "NORAD_CAT_ID": "16937",
        "ELEMENT_SET_NO": "999",
        "REV_AT_EPOCH": "306",
        "BSTAR": "0.00269490000000",
        "MEAN_MOTION_DOT": "0.06329737",
        "MEAN_MOTION_DDOT": "0.0000267130000",
        "SEMIMAJOR_AXIS": "6629.674",
        "PERIOD": "89.535",
        "APOAPSIS": "325.707",
        "PERIAPSIS": "177.371",
        "OBJECT_TYPE": "PAYLOAD",
        "RCS_SIZE": null,
        "COUNTRY_CODE": null,
        "LAUNCH_DATE": null,
        "SITE": null,
        "DECAY_DATE": "1986-09-28",
        "FILE": "34511",
        "GP_ID": "15040479",
        "TLE_LINE0": "0 USA 19",
        "TLE_LINE1": "1 16937U 86069A   86268.39247979  .06329737 +26713-4 +26949-2 0  9997",
        "TLE_LINE2": "2 16937 039.0531 276.4305 0111873 171.4053 189.5525 16.08291950003063"
    }
]

To actually see live data and query the actual Space-Track.org servers, you'll need to make a couple of changes within the Unreal Engine Editor.

You'll need to edit the map/level. Specifically, edit BOTH debris field actors (BP_DebrisActor-*):

• Uncheck "Use Test URL"
• Set "Space Track User" and "Space Track Password" to your login credentials at Space-Track.com

Run the app again and check the Editor's Output Log. You will see that you're now querying and visualizing up-to-the-minute data from Space-Track.org.

Space-Track.org asks API users to be responsible and adhere usage caps. If you were actually building a visualization app for many users, you'd need to query the Space-Track.org server from your own server and cache the data. If you cache the data your servers can then handle as many users as needed without adding additional load to the Space-Track.org servers. Be careful not to violate the terms of use, of course, which prohibit arbitrarily redistributing data from the SatCat.