FA-69727 / Orbital propagation / Member archive

Exponential atmosphere drag: Density band is the lowest band below the altitude · case 02

Upper-atmosphere densities are extrapolated from sea level.

Member previewVariant 2 · 3 implementations · 7 checks per implementation

Case contract

Input [alt km, v km/s, cd, area m^2, mass kg, rows]: rows are [base km, rho0 kg/m^3, H km]; the band is the highest base <= alt (None below every base). rho=rho0 exp(-(alt-base)/H). Drag acceleration = 0.5 rho (1000 v)^2 cd area/mass (m/s^2). Return [rho, accel] formatted with 7 significant digits.

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
exponential atmosphere drag [250, 7.75, 2.2, 1.0, 100.0, [[0, 1.225, 7.249], [100, 5.297e-07, 5.877], [200, 2.789e-10, 37.105], [300, 1.916e-11, 53.628], [500, 6.967e-13, 63.822], [700, 3.614e-14, 88.667]]]	`[1.289432e-15, 8.519115e-10]`	`[7.248111e-11, 4.788736e-05]`	Failed

MEMBER ARCHIVE

The complete case is available to members.

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

Member access is invitation-based. Sign in with your invited account to inspect the sources.