FA-69577 / Orbital propagation / Member archive

J2 secular node and perigee drift: Nodal rate sign ignores retrograde inclinations · case 02

Sun-synchronous retrograde orbits regress instead of precess.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Input [a km, e, i deg, days]. With mu=398600.4418, Re=6378.137, J2=1.08263e-3, n=sqrt(mu/a^3), p=a(1-e^2): dRAAN/dt=-1.5 n J2 (Re/p)^2 cos i, dargp/dt=0.75 n J2 (Re/p)^2 (5cos^2 i-1). Return [RAAN drift deg, argp drift deg over the interval (rounded 4), sun-synchronous flag: |RAAN rate in deg/day - 0.9856|<0.01].

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
j2 secular node and perigee drift [6878.0, 0.0, 97.4, 2]	`[-1.971, -7.0169, false]`	`[1.971, -7.0169, true]`	Failed

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