FAILURE MAP
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FA-69676 / Orbital propagation / Open access

Orbit energy classification: Hyperbolic excess speed omits the factor two · case 01

Departure v-infinity is understated by sqrt(2).

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

v_inf is sqrt(eps).

THE FAILURE

v_inf is sqrt(eps).

Unsuccessful approach: Computing sqrt(2|eps|) for every orbit gives bound orbits a v-infinity.

Case contract

Input [r, v, mu, tol]. eps=v^2/2-mu/r. Parabolic when |eps|<=tol*mu/r, else elliptic (eps<0) or hyperbolic. a=-mu/(2 eps) (None if parabolic), escape speed sqrt(2mu/r), v_inf=sqrt(2 eps) for hyperbolic else None. Return [kind, a rounded 3, vesc rounded 6, vinf rounded 6].

Why this case matters

Orbit determination and mission planning chain many small conversions; one wrong branch or unit silently moves a spacecraft by kilometres.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    r,v,mu,tol=x
    eps=v*v/2-mu/r
    if abs(eps)<=tol*mu/r: kind='parabolic'
    elif eps<0: kind='elliptic'
    else: kind='hyperbolic'
    a=None if kind=='parabolic' else round(-mu/(2*eps),3)
    vesc=math.sqrt(2*mu/r)
    vinf=round(math.sqrt(eps),6) if kind=='hyperbolic' else None
    return [kind,a,round(vesc,6),vinf]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214])], [('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [42164.0, 3.07, 398600.4418, 1e-06]', [42164.0, 3.07, 398600.4418, 1e-06], ['elliptic', 42036.503, 4.348235, None]), ('orbit energy classification [6678.0, 11.5, 398600.4418, 1e-06]', [6678.0, 11.5, 398600.4418, 1e-06], ['hyperbolic', -30964.528, 10.925987, 3.58787])], [('orbit energy classification [6678.0, 11.5, 398600.4418, 1e-06]', [6678.0, 11.5, 398600.4418, 1e-06], ['hyperbolic', -30964.528, 10.925987, 3.58787]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [42164.0, 3.07, 398600.4418, 1e-06]', [42164.0, 3.07, 398600.4418, 1e-06], ['elliptic', 42036.503, 4.348235, None]), ('orbit energy classification [2.0, 1.0, 1.0, 0.0001]', [2.0, 1.0, 1.0, 0.0001], ['parabolic', None, 1.0, None]), ('orbit energy classification [100.0, 0.1414, 1.0, 0.001]', [100.0, 0.1414, 1.0, 0.001], ['parabolic', None, 0.141421, None]), ('orbit energy classification [1.0, 1.05, 1.0, 0.5]', [1.0, 1.05, 1.0, 0.5], ['parabolic', None, 1.414214, None])], [('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [2.0, 1.0, 1.0, 0.0001]', [2.0, 1.0, 1.0, 0.0001], ['parabolic', None, 1.0, None]), ('orbit energy classification [100.0, 0.1414, 1.0, 0.001]', [100.0, 0.1414, 1.0, 0.001], ['parabolic', None, 0.141421, None]), ('orbit energy classification [1.0, 1.05, 1.0, 0.5]', [1.0, 1.05, 1.0, 0.5], ['parabolic', None, 1.414214, None]), ('orbit energy classification [2.0, 0.8, 1.0, 0.5]', [2.0, 0.8, 1.0, 0.5], ['parabolic', None, 1.0, None]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None])], [('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [2.0, 0.8, 1.0, 0.5]', [2.0, 0.8, 1.0, 0.5], ['parabolic', None, 1.0, None]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None]), ('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]['hyperbolic', -144726.71, 10.671731, 1.17349]['hyperbolic', -144726.71, 10.671731, 1.659566]Failed
orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]['elliptic', 6915.843, 10.671731, None]['elliptic', 6915.843, 10.671731, None]Passed
orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]['elliptic', 10790332.769, 10.671731, None]['elliptic', 10790332.769, 10.671731, None]Passed
orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]['parabolic', None, 10.671731, None]['parabolic', None, 10.671731, None]Passed
orbit energy classification [1.0, 1.4142, 1.0, 0.001]['parabolic', None, 1.414214, None]['parabolic', None, 1.414214, None]Passed
orbit energy classification [1.0, 1.0, 1.0, 0.001]['elliptic', 1.0, 1.414214, None]['elliptic', 1.0, 1.414214, None]Passed
orbit energy classification [1.0, 2.0, 1.0, 0.001]['hyperbolic', -0.5, 1.414214, 1.0]['hyperbolic', -0.5, 1.414214, 1.414214]Failed

SHA-256 / bc6ae2667254b8b14d772cddbf05b392402d529c9d1917dd69e86ec9b4461a06

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    r,v,mu,tol=x
    eps=v*v/2-mu/r
    if abs(eps)<=tol*mu/r: kind='parabolic'
    elif eps<0: kind='elliptic'
    else: kind='hyperbolic'
    a=None if kind=='parabolic' else round(-mu/(2*eps),3)
    vesc=math.sqrt(2*mu/r)
    vinf=round(math.sqrt(2*abs(eps)),6)
    return [kind,a,round(vesc,6),vinf]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214])], [('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [42164.0, 3.07, 398600.4418, 1e-06]', [42164.0, 3.07, 398600.4418, 1e-06], ['elliptic', 42036.503, 4.348235, None]), ('orbit energy classification [6678.0, 11.5, 398600.4418, 1e-06]', [6678.0, 11.5, 398600.4418, 1e-06], ['hyperbolic', -30964.528, 10.925987, 3.58787])], [('orbit energy classification [6678.0, 11.5, 398600.4418, 1e-06]', [6678.0, 11.5, 398600.4418, 1e-06], ['hyperbolic', -30964.528, 10.925987, 3.58787]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None]), ('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [42164.0, 3.07, 398600.4418, 1e-06]', [42164.0, 3.07, 398600.4418, 1e-06], ['elliptic', 42036.503, 4.348235, None]), ('orbit energy classification [2.0, 1.0, 1.0, 0.0001]', [2.0, 1.0, 1.0, 0.0001], ['parabolic', None, 1.0, None]), ('orbit energy classification [100.0, 0.1414, 1.0, 0.001]', [100.0, 0.1414, 1.0, 0.001], ['parabolic', None, 0.141421, None]), ('orbit energy classification [1.0, 1.05, 1.0, 0.5]', [1.0, 1.05, 1.0, 0.5], ['parabolic', None, 1.414214, None])], [('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [1.0, 1.4142, 1.0, 0.001]', [1.0, 1.4142, 1.0, 0.001], ['parabolic', None, 1.414214, None]), ('orbit energy classification [2.0, 1.0, 1.0, 0.0001]', [2.0, 1.0, 1.0, 0.0001], ['parabolic', None, 1.0, None]), ('orbit energy classification [100.0, 0.1414, 1.0, 0.001]', [100.0, 0.1414, 1.0, 0.001], ['parabolic', None, 0.141421, None]), ('orbit energy classification [1.0, 1.05, 1.0, 0.5]', [1.0, 1.05, 1.0, 0.5], ['parabolic', None, 1.414214, None]), ('orbit energy classification [2.0, 0.8, 1.0, 0.5]', [2.0, 0.8, 1.0, 0.5], ['parabolic', None, 1.0, None]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None])], [('orbit energy classification [1.0, 2.0, 1.0, 0.001]', [1.0, 2.0, 1.0, 0.001], ['hyperbolic', -0.5, 1.414214, 1.414214]), ('orbit energy classification [1.0, 1.0, 1.0, 0.001]', [1.0, 1.0, 1.0, 0.001], ['elliptic', 1.0, 1.414214, None]), ('orbit energy classification [2.0, 0.8, 1.0, 0.5]', [2.0, 0.8, 1.0, 0.5], ['parabolic', None, 1.0, None]), ('orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]', [7000.0, 7.5, 398600.4418, 1e-06], ['elliptic', 6915.843, 10.671731, None]), ('orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]', [7000.0, 10.8, 398600.4418, 1e-06], ['hyperbolic', -144726.71, 10.671731, 1.659566]), ('orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]', [7000.0, 10.67, 398600.4418, 1e-06], ['elliptic', 10790332.769, 10.671731, None]), ('orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]', [7000.0, 10.6713, 398600.4418, 0.0001], ['parabolic', None, 10.671731, None])]]
for label, args, expected in fixtures[N-1]:
    check(label, solve(args), expected)
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
orbit energy classification [7000.0, 10.8, 398600.4418, 1e-06]['hyperbolic', -144726.71, 10.671731, 1.659566]['hyperbolic', -144726.71, 10.671731, 1.659566]Passed
orbit energy classification [7000.0, 7.5, 398600.4418, 1e-06]['elliptic', 6915.843, 10.671731, 7.591827]['elliptic', 6915.843, 10.671731, None]Failed
orbit energy classification [7000.0, 10.67, 398600.4418, 1e-06]['elliptic', 10790332.769, 10.671731, 0.192199]['elliptic', 10790332.769, 10.671731, None]Failed
orbit energy classification [7000.0, 10.6713, 398600.4418, 0.0001]['parabolic', None, 10.671731, 0.0959]['parabolic', None, 10.671731, None]Failed
orbit energy classification [1.0, 1.4142, 1.0, 0.001]['parabolic', None, 1.414214, 0.006194]['parabolic', None, 1.414214, None]Failed
orbit energy classification [1.0, 1.0, 1.0, 0.001]['elliptic', 1.0, 1.414214, 1.0]['elliptic', 1.0, 1.414214, None]Failed
orbit energy classification [1.0, 2.0, 1.0, 0.001]['hyperbolic', -0.5, 1.414214, 1.414214]['hyperbolic', -0.5, 1.414214, 1.414214]Passed

SHA-256 / 5237a4723db633fabac92aa6aa395aaf91b3ae9fc38eabde3cd40aed91e8c2bd

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

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Verification & scope

A deterministic toy two-body model with stipulated constants and conventions; not flight dynamics software or a validated SGP4 implementation. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:48:13.606348+00:00.

Case digest / 22c446d665c817e44045dc4b9397bf039cd7ba9f30e53eb17094d02ad34d82a2