FA-69441 / Orbital propagation / Open access

Two-line element set line 1: Two-digit epoch years pivot at 50 · case 01

Element sets from 1950-1956 or 2050-2056 are placed in the wrong century.

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

ROOT CAUSE

The two-digit year pivot is 50 instead of 57.

VERIFIED REPAIR

Years 57-99 are 1900s, 00-56 are 2000s.

Unsuccessful approach: Using a strict >57 test moves 1957 into 2057.

Case contract

Input one TLE line-1 string (exactly 69 characters, starting "1", else None). Epoch year from columns 19-20 (57-99 -> 1900s, 00-56 -> 2000s), epoch day 21-32, ndot/2 34-43, BSTAR 54-61 in assumed-decimal exponent form (" 34123-4" = 0.34123e-4, sign first), checksum column 69 (digits plus 1 per "-", mod 10). Return [year, day, ndot2, bstar rounded 14, checksum_ok].

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):
    s=x
    if len(s)!=69 or s[0]!='1': return None
    yy=int(s[18:20]); year=1900+yy if yy>=50 else 2000+yy
    day=float(s[20:32]); ndot=float(s[33:43])
    f=s[53:61].strip()
    sign=-1 if f[0]=='-' else 1
    f=f.lstrip('+-')
    mant,ex=f[:-2],f[-2:]
    bstar=sign*float('0.'+mant)*10**int(ex)
    cs=sum(int(c) if c.isdigit() else (1 if c=='-' else 0) for c in s[:68])%10
    return [year,day,ndot,round(bstar,14),cs==int(s[68])]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None)], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True])], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', 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 fixture	Actual	Expected	Outcome
two-line element set line 1 "1 22222U 56001A 56365.99999999 -.00000050 -12345-5 10000+1 0 55"	`[1956, 365.99999999, -5e-07, 1.0, True]`	`[2056, 365.99999999, -5e-07, 1.0, True]`	Failed
two-line element set line 1 "1 11111U 75001A 57100.00000000 .00000000 00000-0 00000+0 0 14"	`[1957, 100.0, 0.0, 0.0, True]`	`[1957, 100.0, 0.0, 0.0, True]`	Passed
two-line element set line 1 "1 25544U 98067A 08264.51782528 -.00002182 00000-0 -11606-4 0 2927"	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	Passed
two-line element set line 1 "1 43013U 17073A 26001.50000000 .00000123 00000-0 34123-4 0 9996"	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	Passed
two-line element set line 1 "1 33333U 99025B 99032.25000000 .00012345 00000-0 -50000-3 0 176"	`[1999, 32.25, 0.00012345, -0.0005, False]`	`[1999, 32.25, 0.00012345, -0.0005, False]`	Passed
two-line element set line 1 "1 44444U 20001C 00012.00000000 .10000000 00000-0 12345+2 0 882"	`[2000, 12.0, 0.1, 12.345, True]`	`[2000, 12.0, 0.1, 12.345, True]`	Passed
two-line element set line 1 "1 45555U 19050Z 50200.12500000 -.00000001 00000-0 99999-9 0 12343"	`[1950, 200.125, -1e-08, 9.9999e-10, True]`	`[2050, 200.125, -1e-08, 9.9999e-10, True]`	Failed

SHA-256 / 3a6fc5b30681375eec9e9ed03f33dd7b8a229dfa0448b8e4cf77a3d36ca090ff

2 / The unsuccessful fix

Exit 1

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    s=x
    if len(s)!=69 or s[0]!='1': return None
    yy=int(s[18:20]); year=1900+yy if yy>57 else 2000+yy
    day=float(s[20:32]); ndot=float(s[33:43])
    f=s[53:61].strip()
    sign=-1 if f[0]=='-' else 1
    f=f.lstrip('+-')
    mant,ex=f[:-2],f[-2:]
    bstar=sign*float('0.'+mant)*10**int(ex)
    cs=sum(int(c) if c.isdigit() else (1 if c=='-' else 0) for c in s[:68])%10
    return [year,day,ndot,round(bstar,14),cs==int(s[68])]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None)], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True])], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', 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 fixture	Actual	Expected	Outcome
two-line element set line 1 "1 22222U 56001A 56365.99999999 -.00000050 -12345-5 10000+1 0 55"	`[2056, 365.99999999, -5e-07, 1.0, True]`	`[2056, 365.99999999, -5e-07, 1.0, True]`	Passed
two-line element set line 1 "1 11111U 75001A 57100.00000000 .00000000 00000-0 00000+0 0 14"	`[2057, 100.0, 0.0, 0.0, True]`	`[1957, 100.0, 0.0, 0.0, True]`	Failed
two-line element set line 1 "1 25544U 98067A 08264.51782528 -.00002182 00000-0 -11606-4 0 2927"	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	Passed
two-line element set line 1 "1 43013U 17073A 26001.50000000 .00000123 00000-0 34123-4 0 9996"	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	Passed
two-line element set line 1 "1 33333U 99025B 99032.25000000 .00012345 00000-0 -50000-3 0 176"	`[1999, 32.25, 0.00012345, -0.0005, False]`	`[1999, 32.25, 0.00012345, -0.0005, False]`	Passed
two-line element set line 1 "1 44444U 20001C 00012.00000000 .10000000 00000-0 12345+2 0 882"	`[2000, 12.0, 0.1, 12.345, True]`	`[2000, 12.0, 0.1, 12.345, True]`	Passed
two-line element set line 1 "1 45555U 19050Z 50200.12500000 -.00000001 00000-0 99999-9 0 12343"	`[2050, 200.125, -1e-08, 9.9999e-10, True]`	`[2050, 200.125, -1e-08, 9.9999e-10, True]`	Passed

SHA-256 / 02105af12ac196fc3660ce0a4e146cb4c72f599d3778fdd6af065e0dc635e4be

3 / The verified repair

Exit 0

"""Failure Map reference implementation. Python standard library only."""
import json
import math
N = 1
observations = []
def solve(x):
    s=x
    if len(s)!=69 or s[0]!='1': return None
    yy=int(s[18:20]); year=1900+yy if yy>=57 else 2000+yy
    day=float(s[20:32]); ndot=float(s[33:43])
    f=s[53:61].strip()
    sign=-1 if f[0]=='-' else 1
    f=f.lstrip('+-')
    mant,ex=f[:-2],f[-2:]
    bstar=sign*float('0.'+mant)*10**int(ex)
    cs=sum(int(c) if c.isdigit() else (1 if c=='-' else 0) for c in s[:68])%10
    return [year,day,ndot,round(bstar,14),cs==int(s[68])]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
fixtures = [[('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None)], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', None), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True])], [('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  2927', [2008, 264.51782528, -2.182e-05, -1.1606e-05, True]), ('two-line element set line 1 "1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '1 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', [2026, 1.5, 1.23e-06, 3.4123e-05, True]), ('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True])], [('two-line element set line 1 "1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55"', '1 22222U 56001A   56365.99999999 -.00000050 -12345-5  10000+1 0    55', [2056, 365.99999999, -5e-07, 1.0, True]), ('two-line element set line 1 "1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14"', '1 11111U 75001A   57100.00000000  .00000000  00000-0  00000+0 0    14', [1957, 100.0, 0.0, 0.0, True]), ('two-line element set line 1 "1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176"', '1 33333U 99025B   99032.25000000  .00012345  00000-0 -50000-3 0   176', [1999, 32.25, 0.00012345, -0.0005, False]), ('two-line element set line 1 "1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882"', '1 44444U 20001C   00012.00000000  .10000000  00000-0  12345+2 0   882', [2000, 12.0, 0.1, 12.345, True]), ('two-line element set line 1 "1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343"', '1 45555U 19050Z   50200.12500000 -.00000001  00000-0  99999-9 0 12343', [2050, 200.125, -1e-08, 9.9999e-10, True]), ('two-line element set line 1 "1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292"', '1 25544U 98067A   08264.51782528 -.00002182  00000-0 -11606-4 0  292', None), ('two-line element set line 1 "2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996"', '2 43013U 17073A   26001.50000000  .00000123  00000-0  34123-4 0  9996', 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 fixture	Actual	Expected	Outcome
two-line element set line 1 "1 22222U 56001A 56365.99999999 -.00000050 -12345-5 10000+1 0 55"	`[2056, 365.99999999, -5e-07, 1.0, True]`	`[2056, 365.99999999, -5e-07, 1.0, True]`	Passed
two-line element set line 1 "1 11111U 75001A 57100.00000000 .00000000 00000-0 00000+0 0 14"	`[1957, 100.0, 0.0, 0.0, True]`	`[1957, 100.0, 0.0, 0.0, True]`	Passed
two-line element set line 1 "1 25544U 98067A 08264.51782528 -.00002182 00000-0 -11606-4 0 2927"	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	`[2008, 264.51782528, -2.182e-05, -1.1606e-05, True]`	Passed
two-line element set line 1 "1 43013U 17073A 26001.50000000 .00000123 00000-0 34123-4 0 9996"	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	`[2026, 1.5, 1.23e-06, 3.4123e-05, True]`	Passed
two-line element set line 1 "1 33333U 99025B 99032.25000000 .00012345 00000-0 -50000-3 0 176"	`[1999, 32.25, 0.00012345, -0.0005, False]`	`[1999, 32.25, 0.00012345, -0.0005, False]`	Passed
two-line element set line 1 "1 44444U 20001C 00012.00000000 .10000000 00000-0 12345+2 0 882"	`[2000, 12.0, 0.1, 12.345, True]`	`[2000, 12.0, 0.1, 12.345, True]`	Passed
two-line element set line 1 "1 45555U 19050Z 50200.12500000 -.00000001 00000-0 99999-9 0 12343"	`[2050, 200.125, -1e-08, 9.9999e-10, True]`	`[2050, 200.125, -1e-08, 9.9999e-10, True]`	Passed

SHA-256 / 93ada67a35d0bf7e9bde5d19d71cd95350e585081e575190b4c55c12a97cbb37

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 2026-09-29T14:48:11.417538+00:00.

Case digest / 06ecfa502b3259fbefd22fcc3910b0452fa801da3cbc2a9260730c51cf9bb618