Class: Satellite (Subclass of OrientedPoint)

The Satellite class extends OrientedPoint to represent satellites in orbit. It adds TLE (Two-Line Element) data management and automatic position/orientation updates based on time.

Constructor

constructor(geometry: THREE.Group, tle: string, orientationMode?: OrientationMode, cameraConfig?: CameraConfig)

Parameter	Type	Description
geometry	THREE.Group	A THREE.Group object representing the satellite in 3D space
tle	string	The Two-Line Element (TLE) data for the satellite
orientationMode	OrientationMode	Defines how the satellite's orientation is determined
cameraConfig	CameraConfig	(Optional) Configuration for the satellite's camera

Static Methods

fromNoradId

Creates a new Satellite instance by fetching TLE data using a NORAD ID.

static async fromNoradId(
  geometry: THREE.Group,
  noradId: string,
  orientationMode: OrientationMode,
  camera_orientation?: [number, number, number, number]
): Promise<Satellite>

TIP

Remember fromNoradId must always be awaited in user scripts.

Methods

update

Updates the satellite's position and orientation based on its TLE data for a given timestamp.

Parameter	Type	Description
timestamp	Date	The time for which to calculate the position
state	State	Application state containing required scene data

Throws an error if TLE data cannot be parsed or if position calculation fails.

OrientationMode

The OrientationMode type defines how a satellite's orientation is determined. It can be either:

Fixed Orientation

{ 
  type: 'fixed';
  ecef_quaternion: [number, number, number, number] 
}

Maintains a constant orientation in ECEF coordinates specified by a quaternion.

Dynamic Orientation

{
  type: 'dynamic';
  primaryBodyVector: Vector3 | string;
  secondaryBodyVector: Vector3 | string;
  primaryTargetVector: Vector3 | NamedTargets;
  secondaryTargetVector: Vector3 | NamedTargets;
}

Continuously updates orientation to align body vectors with target vectors:

• primaryBodyVector: Body frame vector to align (typically 'x', 'y', or 'z')
• secondaryBodyVector: Secondary body frame vector for full attitude determination
• primaryTargetVector: Target direction for primary alignment
• secondaryTargetVector: Target direction for secondary alignment

NamedTargets

The following named targets are available for dynamic orientation:

Target	Description
Moon	Direction to the Moon
Sun	Direction to the Sun
Velocity	Satellite's velocity vector
Nadir	Direction to Earth's center (pointing down)
TargetPointing	Points towards a specific target. Either an existing point reference by name or a fixed ECEF coordinate

Using TargetPointing requires passing additional data unlike the others.

Example

Some targets are fully specified by the simulation like Moon or Nadir and can simply be used as:

NamedTarget.Moon

However, if we want to point at a specific target we need to supply that too:

// Always point towards the default sat. The point must have been added before.
NamedTarget.TargetPointing("sat");
// or perhaps look at a fixed point in space
NamedTarget.TargetPointing([2000, 3000, 3000]);

addSatellite

Adds a new satellite to the scene with specified TLE data and orientation mode.

Arguments

Parameter	Type	Description
name	string	Unique identifier for the satellite
tleSource	TleSource	Source of TLE data (either direct TLE or NORAD ID)
orientationMode	OrientationMode	Configuration for how the satellite maintains its orientation

TleSource

Can be either:

{ type: 'tle'; tle: string }
// or
{ type: 'noradId'; noradId: string }

Returns

Promise<void> - Must be awaited.

Example

// Add a satellite using its NORAD ID
await addSatellite(
  'sentinel2b',
  {
    type: 'noradId',
    noradId: '42063',
  },
  {
    type: 'dynamic',
    primaryBodyVector: 'z',
    secondaryBodyVector: 'y',
    primaryTargetVector: NamedTargets.Nadir,
    secondaryTargetVector: NamedTargets.Velocity,
  },
);

// Or using direct TLE data
await addSatellite(
  'mysat',
  {
    type: 'tle',
    tle: `ISS (ZARYA)
1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927
2 25544  51.6416 247.4627 0006703 130.5360 325.0288 15.72125391563537`,
  },
  {
    type: 'dynamic',
    primaryBodyVector: 'z',
    secondaryBodyVector: 'y',
    primaryTargetVector: NamedTargets.Moon,
    secondaryTargetVector: NamedTargets.Velocity,
  },
);