Home›Maneuver Tracker›Close Approaches›SDA-NG-T1TL-407 ⟷ COSMOS 1375 DEB
HighCross-border
On permanent record
Final forecastFinal forecast, made 16 min before the pass.
Closest approach7 Nov 202615:47 UTC
Relative speed12.01 km/sat the closest approach
Altitude947 kmlow Earth orbit
Last confirmed7 Nov15:31 UTC · final forecast

US SDA-NG-T1TL-407 and RU COSMOS 1375 DEB were predicted to reach a closest approach of 2.73 km at 2026-11-07 15:47 UTC, at a relative speed of 12.01 km/s. Final forecast, made 16 min before the pass. This is a cross-border encounter between objects of different nations, the kind of event closely watched for space-security implications. 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
NORAD 100989
CountryUS
Launched2026-10-10
COSPAR2026-231G
Maneuver capableUnknown
NORAD 18278
CountryCIS
Launched1982-06-06
COSPAR1982-055BA
Maneuver capableNo
Uncontrolled debris fragment tracked by the public catalogue. About space debris →

Where This Happens

Altitude context
DEBRIS BELT 700–1000 KM2006001,0001,5002,000 kmTHIS PASS · 947 KMISS 420Starlink 550

At 947 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 · SDA-NG-T1TL-407 ⟷ COSMOS 1375 DEB
2026-11-07 15:472.73 km Final forecast12.01 km/s947 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 Nothing is overwritten: a withdrawn forecast keeps its figure, with the newer check beside it, and the best estimate after the pass is a row of its own.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
7 Nov 12:51 UTC2.73 km Forecast7 Nov 15:47 UTC7 Nov 02:13 UTCRe-check
7 Nov 11:27 UTC2.71 km Forecast7 Nov 15:47 UTC6 Nov 17:33 UTCRe-check
7 Nov 11:05 UTC9.16 km Forecast7 Nov 15:47 UTC6 Nov 17:33 UTCScreen

These Objects Elsewhere

Other screened approaches · 7 days
670 m11-01 22:03 UTC
SDA-NG-T1TL-407THOR ABLESTAR DEB
3.36 km11-02 06:36 UTC
SDA-NG-T1TL-407THORAD AGENA D DEB
3.79 km11-04 12:38 UTC
SDA-NG-T1TL-407FENGYUN 1C 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 →

✓ Permanent record. This encounter met the notability thresholds and keeps an archived page after the pass.