Home›Maneuver Tracker›Close Approaches›COSMOS 2135 ⟷ SL-8 DEB
HighProximity
RussiaCOSMOS 2135NORAD 21130 · launched Feb 1991Military payload
4.69kmPredicted miss distance
RussiaSL-8 DEBNORAD 18276 · launched Jun 1987Debris
Final forecastFinal forecast, made 18 min before the pass.
Closest approach27 Oct 202614:41 UTC
Relative speed9.02 km/sat the closest approach
Altitude965 kmlow Earth orbit
Last confirmed27 Oct14:23 UTC · final forecast
Track COSMOS 2135Track SL-8 DEBAll approaches
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RU COSMOS 2135 and RU SL-8 DEB were predicted to reach a closest approach of 4.69 km at 2026-10-27 14:41 UTC, at a relative speed of 9.02 km/s. Final forecast, made 18 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 2135Payload
NORAD 21130
CountryCIS
Launched1991-02-26
OrbitLEO · 920 × 1,016 km
COSPAR1991-013A
Maneuver capableUnknown
Profile →Globe →
SL-8 DEBDebris
NORAD 18276
CountryCIS
Launched1987-06-23
OrbitLEO · 963 × 982 km
COSPAR1987-054D
Maneuver capableNo
Uncontrolled debris fragment tracked by the public catalogue. About space debris →
Profile →Globe →

Where This Happens

Altitude context
DEBRIS BELT 700–1000 KM2006001,0001,5002,000 kmTHIS PASS · 965 KMISS 420Starlink 550

At 965 km this pass sits inside the most congested band in low Earth orbit, home to the debris left by the 2007 ASAT test and the 2009 collision. 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 2135 ⟷ SL-8 DEB
2026-10-27 14:414.69 km Final forecast9.02 km/s965 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
27 Oct 13:00 UTC4.69 km Forecast27 Oct 14:41 UTC27 Oct 05:31 UTCRe-check
27 Oct 09:06 UTC4.72 km Forecast27 Oct 14:41 UTC26 Oct 22:33 UTCRe-check
26 Oct 16:41 UTC4.73 km Forecast27 Oct 14:41 UTC26 Oct 05:08 UTCScreen

These Objects Elsewhere

Other screened approaches · 7 days
2.31 km10-24 03:42 UTC
COSMOS 2327SL-8 DEB
2.72 km10-30 03:37 UTC
COSMOS 2135SL-8 R/B
3.03 km10-22 13:38 UTC
COSMOS 2135THOR ABLESTAR DEB

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 →

Cite this encounter: Orbital Radar — “COSMOS 2135 ⟷ SL-8 DEB: 4.69 km predicted close approach”, https://orbitalradar.com/conjunction/18276-21130 (accessed 2026-10-29).