FA-69462 / Orbital propagation / Member archive

Two-line element set line 1: Exponent is always treated as negative · case 02

Large positive-exponent drag terms shrink to tiny values.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

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.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
two-line element set line 1 "1 44444U 20001C 00012.00000000 .10000000 00000-0 12345+2 0 882"	`[2000, 12.0, 0.1, 0.0012345, true]`	`[2000, 12.0, 0.1, 12.345, true]`	Failed

MEMBER ARCHIVE

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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