Hohmann rendezvous phase angle API

Returns the required departure phase angle (target lead angle) for a Hohmann transfer to rendezvous with a body on the destination orbit, plus transfer time and synodic period. Answers 'What is the launch phase angle to Mars?', 'When is the transfer window?'.

Price$0.08per request

MethodPOST

Route/v1/space/hohmann-phase-angle

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

spaceastronomyphase-anglehohmannrendezvouslaunch-windowmission-planningastrodynamics

API URLhttps://x402.hexl.dev/v1/space/hohmann-phase-angle

Integration docs

Example request

{
  "body": "sun",
  "r1M": 149597870700,
  "r2M": 227900000000
}

Example response

{
  "body": "sun",
  "mu": 132712440018000000000,
  "r1M": 149597870700,
  "r2M": 227900000000,
  "transferTimeS": 22362524.1,
  "transferTimeDays": 258.82551,
  "phaseAngleRad": 0.77371014,
  "phaseAngleDeg": 44.330325,
  "synodicPeriodS": 67407345.278,
  "synodicPeriodDays": 780.177607,
  "interpretation": "Depart when the target leads the departure point by 44.3°."
}

Input schema

{
  "type": "object",
  "required": [
    "r1M",
    "r2M"
  ],
  "properties": {
    "body": {
      "type": "string",
      "examples": [
        "sun"
      ]
    },
    "mu": {
      "type": "number"
    },
    "centralMassKg": {
      "type": "number"
    },
    "r1M": {
      "type": "number",
      "examples": [
        149597870700
      ]
    },
    "r2M": {
      "type": "number",
      "examples": [
        227900000000
      ]
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}