Source: https://guthlabs.ai/docs/instruments/ground-track-orbital-period-vs-altitude/implementation/

instrument implementation / implementation-contract

# Ground Track / Orbital Period vs Altitude implementation

A source-bound implementation contract for Ground Track / Orbital Period vs Altitude; deployment and executable qualification remain separate.

Status: **VERIFIED_CLEAN**Lifecycle: **implementation-contract**

## Binding contract

This record describes what an executable surface must bind and validate. It does not claim that a public calculator, package, or production route is deployed.

**Record owner**: Guth Instruments

**Lifecycle**: verified-clean

**Evidence ID**: t4-256

**Effect**: Computation or source lookup only

## Input and validation requirements

A zero supplied period makes the orbits-per-day calculation undefined, and an unspecified altitude unit permits materially different outputs for the same numeric input.

## Required corrections

No binding erratum is attached to this unique-name record. Implementers must still preserve the declared units, domain, and failure behavior.

## Inspectable interface fixture

The sample below is evidence for interface and validation tests, not a production implementation.

````
{
  "inputs": {
    "altitude_km": 0,
    "mu_km3_s2": 398600.4418,
    "earth_radius_km": 6378.137
  },
  "expected_outputs": {
    "period_s": 5069.34,
    "orbits_per_day": 17.0436
  },
  "working": "a = Rₑ + h = 6378.137 + 0 = 6378.137 km. T = 2π√(a³/μ) = 2π√(6378.137³ / 398600.4418) ≈ 5069.34 s. Orbits/day = 86400 / 5069.34 ≈ 17.0436."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/ground-track-orbital-period-vs-altitude/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/ground-track-orbital-period-vs-altitude/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/ground-track-orbital-period-vs-altitude/qualification/>)

## Sources and evidence

These pointers bind the page to evidence. They do not grant authority or collapse verification into deployment.

- `VERIFIED_LEDGER.json`

- `evidence-tranche4/tranche4-results.json`