Adding Satellites

This workflow demonstrates how to add a satellite to the scene and control its orientation dynamically. We'll create a satellite that tracks the Moon while maintaining its attitude control.

Basic Satellite Setup

Here's a complete example that:

1. Resets the scene
2. Sets a specific date/time
3. Adds a satellite using its NORAD ID
4. Configures it to track the Moon

// Reset the scene to start fresh
reset();

// Set a specific date for consistent Moon position
let date = new Date(2025, 1, 20, 10);
setTime(date);

// Add a satellite using its NORAD ID
await addSatellite(
  'hf1a',
  {
    type: 'noradId',
    noradId: '60562', // NORAD ID for the satellite
  },
  {
    type: 'dynamic',
    primaryBodyVector: 'z',
    secondaryBodyVector: 'y',
    primaryTargetVector: NamedTargets.Moon,
    secondaryTargetVector: NamedTargets.Velocity,
  },
);
pauseSimTime();

// See the satellite orbit by running `resumeSimTime()` or
// clicking on the UI
// resumeSimTime();

Now you could add a new cell at the bottom (docs here) and then run the following cell

point("hf1a").addCamera(
  {
    orientation:[0, 0 , 0, 1],
    fov: 10,
  }
);
switchCamera(point("hf1a").camera);

which will add a camera with a 5 degree field of view and shows what the satellite is looking at.

Looking at another satellite!

Here's an example that demonstrates two satellites interacting - one tracking the Moon while being observed by another satellite:

// Reset scene and set specific date
reset();
let date = new Date('2025-01-23T15:48:00Z');
setTime(date);

// Add Sentinel-2B with Moon tracking configuration
await addSatellite(
  'sentinel2b',
  {
    type: 'noradId',
    noradId: '42063',
  },
  {
    type: 'dynamic',
    primaryBodyVector: 'z',
    secondaryBodyVector: 'y',
    primaryTargetVector: NamedTargets.Nadir,
    secondaryTargetVector: NamedTargets.Velocity,
  },
);

// Add HF1A configured to track Sentinel-2B
await addSatellite(
  'hf1a',
  {
    type: 'noradId',
    noradId: '60562',
  },
  {
    type: 'dynamic',
    primaryBodyVector: 'z',
    secondaryBodyVector: 'y',
    primaryTargetVector: NamedTargets.TargetPointing('sentinel2b'),
    secondaryTargetVector: NamedTargets.Velocity,
  },
);

// Add a camera to HF1A with 90-degree field of view. This is huge but
// otherwise we would only see Sentinel-2B and nothing of the Earth
point('hf1a').addCamera({
  orientation: [0, 0, 0, 1],
  fov: 90,
});

pauseSimTime();

At this point in time Hypefield-1A and Sentinel-2B where flying very close by over the Caribbean Sea. You can now try to go into the Bodies tab and change the color of the points representing both satellites. Then lets watch Sentinel-2B orbit for a few minutes from the point of view Hyperfield-1A.

Copy the following at the bottom of your current script:

switchCamera(point("hf1a").camera);

this will create a new cell that now can be run with (Shift+Enter). Finally adjust the playback speed to around 20x and hit play.

Understanding the sattelite configuration

The addSatellite function takes three main arguments:

1. Name: A string identifier for the satellite in the scene
2. TLE Source: Either a direct TLE string or a NORAD ID to fetch current data
3. Orientation Mode: Controls how the satellite maintains its attitude

Orientation Modes

The orientation configuration can be either:

• Fixed: Uses a constant quaternion orientation
• Dynamic: Continuously updates to track specified targets

For dynamic orientation, you specify:

• primaryBodyVector: Which body axis to point ('x', 'y', or 'z')
• secondaryBodyVector: Secondary body axis for roll reference
• primaryTargetVector: What to point at (Moon, Sun, Nadir, etc.)
• secondaryTargetVector: Secondary alignment target

Available Named Targets

You can use these predefined targets:

• NamedTargets.Moon: Track the Moon
• NamedTargets.Sun: Track the Sun
• NamedTargets.Velocity: Align with orbital velocity
• NamedTargets.Nadir: Point toward Earth's center
• NamedTargets.TargetPointing(<point_name or ECEF coords>): Point at an arbitrary location or moving point

Earth Observation Satellites

Here's a list of some notable Earth observation satellites you can track:

Satellite	NORAD ID	Description
Sentinel-2A	40697	Part of the EU's Copernicus program, provides high-resolution optical imaging
Sentinel-2B	42063	Twin satellite to Sentinel-2A, together they provide 5-day revisit coverage
Sentinel-2C	60989	Next generation Sentinel-2 satellite
PRISMA	44072	Italian hyperspectral imaging satellite
Landsat 9	49260	Latest in the Landsat series, provides medium-resolution multispectral imagery

Tips

• Use pauseSimTime() and resumeSimTime() to control the simulation flow
• The satellite's position updates automatically based on its TLE data
• Dynamic orientation updates happen automatically while time is flowing
• You can have multiple satellites with different tracking configurations