Source: https://guthlabs.ai/docs/instruments/orbital-eccentricity-apsides-solver/implementation/

instrument implementation / implementation-contract

# Orbital Eccentricity/Apsides Solver implementation

A source-bound implementation contract for Orbital Eccentricity/Apsides Solver; 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**: t4-221

**Effect**: Computation or source lookup only

## Input and validation requirements

The solver can encounter an undefined division when a=0. It also needs explicit validity and convention handling at e=1, across e=1, and for negative semimajor axis hyperbolic inputs; otherwise it may return misleading apsides.

## 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": {
    "a": 10000,
    "e": 0.2,
    "distance_unit": "km"
  },
  "expected_outputs": {
    "r_p": 8000,
    "r_a": 12000,
    "distance_unit": "km"
  },
  "working": "r_p = a(1-e) = 10000(1-0.2) = 10000(0.8) = 8000 km.\nr_a = a(1+e) = 10000(1+0.2) = 10000(1.2) = 12000 km."
}
````

## Other records

[01**Overview**](<https://guthlabs.ai/docs/instruments/orbital-eccentricity-apsides-solver/>)[02**Mechanism**](<https://guthlabs.ai/docs/instruments/orbital-eccentricity-apsides-solver/mechanism/>)[04**Qualification**](<https://guthlabs.ai/docs/instruments/orbital-eccentricity-apsides-solver/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`