Home›Maneuver Tracker›Close Approaches›COSMOS 2123 ⟷ COSMOS 823
HighProximity
RussiaCOSMOS 2123NORAD 21089 · launched Feb 1991Military payload
2.70kmPredicted miss distance
RussiaCOSMOS 823NORAD 8873 · launched Jun 1976Military payload
Final forecastFinal forecast, made minutes before the pass.
Closest approach27 Oct 202614:27 UTC
Relative speed14.35 km/sat the closest approach
Altitude996 kmlow Earth orbit
Last confirmed27 Oct14:23 UTC · final forecast
Track COSMOS 2123Track COSMOS 823All approaches
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RU COSMOS 2123 and RU COSMOS 823 were predicted to reach a closest approach of 2.70 km at 2026-10-27 14:27 UTC, at a relative speed of 14.35 km/s. Final forecast, made minutes 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 mattersBoth objects are catalogued as payloads. Screening continues as new element sets arrive; operators act on their own conjunction data.

The Two Objects

Dossiers from the satellite directory
COSMOS 2123Payload
NORAD 21089
CountryCIS
Launched1991-02-05
OrbitLEO · 962 × 1,003 km
COSPAR1991-007A
Maneuver capableUnknown
Profile →Globe →
COSMOS 823Payload
NORAD 8873
CountryCIS
Launched1976-06-02
OrbitLEO · 971 × 1,003 km
COSPAR1976-051A
Maneuver capableUnknown
Profile →Globe →

Where This Happens

Altitude context
DEBRIS BELT 700–1000 KM2006001,0001,5002,000 kmTHIS PASS · 996 KMISS 420Starlink 550

At 996 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 2123 ⟷ COSMOS 823
2026-10-27 14:272.70 km Final forecast14.35 km/s996 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 UTC2.70 km Forecast27 Oct 14:27 UTC27 Oct 07:17 UTCRe-check
27 Oct 09:06 UTC2.71 km Forecast27 Oct 14:27 UTC26 Oct 22:26 UTCRe-check
26 Oct 16:41 UTC2.73 km Forecast27 Oct 14:27 UTC26 Oct 07:12 UTCRe-check
26 Oct 15:07 UTC2.74 km Forecast27 Oct 14:27 UTC25 Oct 19:02 UTCRe-check
26 Oct 14:47 UTC5.35 km Forecast27 Oct 14:27 UTC25 Oct 19:02 UTCScreen

These Objects Elsewhere

Other screened approaches · 7 days
1.15 km10-28 16:31 UTC
COSMOS 2123COSMOS 2407
2.50 km10-23 02:12 UTC
COSMOS 2123COSMOS 1375 DEB
2.77 km10-25 11:35 UTC
COSMOS 2123NIMBUS 2 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 2123 ⟷ COSMOS 823: 2.70 km predicted close approach”, https://orbitalradar.com/conjunction/21089-8873 (accessed 2026-10-28).