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HighProximity
RussiaCOSMOS 2066NORAD 20551 · launched Apr 1990Military payload
4.59kmPredicted miss distance
RussiaCOSMOS 839 DEBNORAD 18272 · launched Jul 1976Military debris
Final forecastFinal forecast, made 8 min before the pass.
After the passBest estimate, from the orbit data published nearest its time: 4.40 km at 29 Oct 01:43 UTC.
Closest approach29 Oct 202601:43 UTC
Relative speed7.06 km/sat the closest approach
Altitude1,454 kmlow Earth orbit
Last confirmed29 Oct01:35 UTC · final forecast
Track COSMOS 2066Track COSMOS 839 DEBAll approaches
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RU COSMOS 2066 and RU COSMOS 839 DEB were predicted to reach a closest approach of 4.59 km at 2026-10-29 01:43 UTC, at a relative speed of 7.06 km/s. Final forecast, made 8 min before the pass. Best estimate after the pass, from the orbit data published nearest its time: 4.40 km at 29 Oct 01:43 UTC. 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 2066Payload
NORAD 20551
CountryCIS
Launched1990-04-06
OrbitLEO · 1,385 × 1,463 km
COSPAR1990-029C
Maneuver capableUnknown
Profile →Globe →
COSMOS 839 DEBDebris
NORAD 18272
CountryCIS
Launched1976-07-08
OrbitMEO · 961 × 2,046 km
COSPAR1976-067BL
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 · 1454 KMISS 420Starlink 550

At 1454 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 2066 ⟷ COSMOS 839 DEB
2026-10-29 01:434.59 km Final forecast7.06 km/s1,454 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
2 Nov 01:27 UTC4.40 km Best estimate29 Oct 01:43 UTC29 Oct 19:27 UTCBest estimate
29 Oct 00:15 UTC4.59 km Forecast29 Oct 01:43 UTC28 Oct 12:08 UTCRe-check
28 Oct 12:35 UTC4.60 km Forecast29 Oct 01:43 UTC27 Oct 23:15 UTCRe-check
28 Oct 12:15 UTC6.21 km Forecast29 Oct 01:43 UTC27 Oct 23:15 UTCScreen

These Objects Elsewhere

Other screened approaches · 7 days
1.46 km10-27 17:25 UTC
COSMOS 2066COSMOS 1291
4.52 km11-03 11:41 UTC
COSMOS 2066COSMOS 2215
4.63 km10-31 10:02 UTC
COSMOS 2066COSMOS 2491 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 →