Home›Maneuver Tracker›Close Approaches›COSMOS 2125 ⟷ SL-8 R/B
HighProximity
RussiaCOSMOS 2125NORAD 21100 · launched Feb 1991Military payload
1.87kmPredicted miss distance
RussiaSL-8 R/BNORAD 12115 · launched Dec 1980Rocket body
Final forecastFinal forecast, made 7 min before the pass.
Closest approach11 Nov 202609:13 UTC
Relative speed13.07 km/sat the closest approach
Altitude1,472 kmlow Earth orbit
Last confirmed11 Nov09:06 UTC · final forecast
Track COSMOS 2125Track SL-8 R/BAll approaches
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RU COSMOS 2125 and RU SL-8 R/B were predicted to reach a closest approach of 1.87 km at 2026-11-11 09:13 UTC, at a relative speed of 13.07 km/s. Final forecast, made 7 min before the pass. Miss distance and time of closest approach are computed by propagating the latest published orbital elements for both objects, and each pass is re-checked every 20 minutes as new element sets are published. See the Satellite Maneuver Tracker for the live picture and space situational awareness for context.

Why it mattersOne side of this pass cannot maneuver, so any avoidance decision rests with the other operator. Screening continues as new element sets arrive.

The Two Objects

Dossiers from the satellite directory
COSMOS 2125Payload
NORAD 21100
CountryCIS
Launched1991-02-12
OrbitLEO · 1,457 × 1,473 km
COSPAR1991-009A
Maneuver capableUnknown
Profile →Globe →
SL-8 R/BR/B
NORAD 12115
CountryCIS
Launched1980-12-23
OrbitLEO · 1,440 × 1,470 km
COSPAR1980-102J
Maneuver capableNo
Spent rocket stage: uncontrolled, tracked by the public catalogue.
Profile →Globe →

Where This Happens

Altitude context
DEBRIS BELT 700–1000 KM2006001,0001,5002,000 kmTHIS PASS · 1472 KMISS 420Starlink 550

At 1472 km this pass sits in low Earth orbit. Objects here stay up for decades: there is too little atmospheric drag to clean the band naturally. Why crowded bands matter →

History Between This Pair

1 predicted pass under 10 km
Pair history · COSMOS 2125 ⟷ SL-8 R/B
2026-11-11 09:131.87 km Final forecast13.07 km/s1,472 kmShown above

Repeat encounters are common for objects in near-intersecting orbital planes. Each pass is re-screened as fresh element sets arrive; "Final forecast" means the screening still predicted it within 45 minutes of its time, "Not re-confirmed" means later screening stopped finding it.

Forecast Record

Every figure published for the pass shown above, newest first. Nothing is overwritten: a withdrawn forecast keeps its figure, with the newer check beside it, and the best estimate after the pass is a row of its own.
Computed · figure · predicted time · orbit data · by
10 Nov 22:26 UTC1.87 km Forecast11 Nov 09:13 UTC10 Nov 05:42 UTCRe-check
10 Nov 22:07 UTC3.51 km Forecast11 Nov 09:13 UTC10 Nov 05:42 UTCScreen

These Objects Elsewhere

Other screened approaches · 7 days
2.70 km11-14 01:02 UTC
COSMOS 2125DELTA 1 DEB
3.48 km11-10 06:45 UTC
COSMOS 2125SL-8 DEB
4.22 km11-09 05:39 UTC
COSMOS 2008COSMOS 2125

How These Numbers Are Computed

Miss distance and TCA come from propagating the latest published orbital elements for both objects and searching for the minimum separation over the screening window. Element sets carry kilometre-scale uncertainty, so figures here describe a close pass, not a collision prediction; a change in either object's published elements re-computes the pass automatically. What is a conjunction? → How conjunction assessment works →