FA-69555 / Orbital propagation / Member archive

Velocity Verlet two-body propagation: Velocity kick uses only the new acceleration · case 05

The scheme becomes first order and energy drifts.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

Input [r0, v0, mu, T, steps]; planar two-body. Velocity Verlet with h=T/steps: p += h v + h^2 a/2; a_new = a(p); v += h (a + a_new)/2; carry a_new. Return final [x,y,vx,vy] rounded to 6 plus specific energy v^2/2-mu/|r| rounded to 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.

One recorded failure

Sample boundary fixture

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

Boundary fixture	Actual	Expected	Outcome
velocity verlet two-body propagation [[1.0, 0.0], [0.0, 1.2], 1.0, 5.0, 25]	`[-1.50136, 0.416525, 0.008929, -0.648172, -0.431717]`	`[-2.100327, 1.143517, -0.394254, -0.35669, -0.276826]`	Failed

MEMBER ARCHIVE

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

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