ISC-11 // Satellite Operations

Conjunction Risk Screener

Rough close-approach screening between a primary satellite and a watchlist of other objects, using SGP4 propagation on publicly available TLEs.

This is a screening heuristic, not a collision-avoidance tool. Two-line elements carry inherent position uncertainty on the order of kilometers that grows with time since the TLE epoch — nowhere near precise enough for an actual maneuver decision. Real conjunction assessment uses Conjunction Data Messages (CDMs) from Space-Track / the 18th Space Defense Squadron, or a commercial SSA provider (LeoLabs, Slingshot, etc.), built on precise ephemerides and covariance data this tool doesn't have. Use this only to flag pairs worth a closer look with a proper data source — never as the basis for an operational decision.

Primary satellite

From fleet

or NORAD ID

Watchlist

Name

NORAD ID

Screening parameters

Lookahead window

Flag threshold (km)

Results

Object	NORAD	Closest approach (UTC)	Min. distance	Rel. velocity	Flag
Load a primary satellite and at least one watchlist object, then run the screening.

Flag thresholds here are just multiples of the distance you set above (routine: >2× threshold, monitor: 1–2×, close: <1×) — a starting point for triage, not an industry-standard probability-of-collision (Pc) calculation.