Lambert solver

Source: AI/Tools/LambertTools.cs

Solve Lambert's problem: given a departure state and an arrival state (with their epochs), compute the transfer-orbit velocities and the Δv at each endpoint for a two-impulse transfer.

SolveLambert

Parameter	Type	Description
initialState	StateVector	Departure state; its epoch is the departure epoch
targetState	StateVector	Arrival state; its epoch must be strictly after the departure epoch
centerOfMotion	CelestialItemsEnum	Gravitating body
isRetrograde	bool, default false	Search retrograde transfers instead of prograde
maxRevolutions	ushort, default 0	Each additional revolution adds up to two more solutions (left + right branches)

Position and velocity must be expressible relative to centerOfMotion; the solver works in ICRF.

Returns a list of LambertSolution, each containing:

• revolutions — number of completed revolutions
• branch — Left / Right when applicable
• v1, v2 — transfer-orbit velocities at the endpoints
• deltaV1, deltaV2 — required Δv at each endpoint
• deltaV — total Δv magnitude
• iterations — solver iteration count (diagnostic)

{
  "initialState": {
    "centerOfMotion": "SUN",
    "epoch": { "dateTime": "2024-01-01T00:00:00", "kind": "UTC" },
    "frame": "ICRF",
    "position": { "x": 1.5e11, "y": 0, "z": 0 },
    "velocity": { "x": 0, "y": 29800, "z": 0 }
  },
  "targetState": {
    "centerOfMotion": "SUN",
    "epoch": { "dateTime": "2024-07-01T00:00:00", "kind": "UTC" },
    "frame": "ICRF",
    "position": { "x": 0, "y": 2.28e11, "z": 0 },
    "velocity": { "x": -24100, "y": 0, "z": 0 }
  },
  "centerOfMotion": "SUN",
  "isRetrograde": false,
  "maxRevolutions": 0
}