Playground - SIMPLETON

Overlays

Spatial grid SGP4 knot points Interpolated samples Tolerance radius Distance line True positions

SPATIAL GRID FLAG

COARSE DETECTION

CONJUNCTION

Preset:

Earth Satellite A (algo) Satellite A (truth) Satellite B (algo) Satellite B (truth) SGP4 Knot Interpolated sample Active grid cell

Black line: the actual Kepler distance between A and B. Green line: the algorithm's view, formed by linearly interpolating between consecutive interpolated step samples. The dot is the TCA within the active segment. Dashed lines mark tolerance-km (yellow) and the 5 km collision threshold (red).

Algorithm view / TCA

Parameters

tolerance-km: coarse-scan distance threshold; pairs whose center-to-center distance falls below this are flagged for refinement. 72

cell-size-km: spatial grid cell edge. Smaller cells mean fewer candidates per cell, but cells smaller than the tolerance can leave a close pair sitting in non-adjacent cells and never compared. 48

step-seconds: time interval between successive position checks. Smaller steps catch fast approaches but multiply propagation work. 9

interpolation-stride: one real SGP4 call per N steps; intermediate positions are filled in by Hermite cubic interpolation on position and velocity at each knot. 50