Home›Maneuver Tracker›Close Approaches›USA 81 ⟷ SENTINEL 2A
medium · PROXIMITY
6.13 kmpredicted miss distance
Final forecastFinal forecast, made 9 min before the pass.
Predicted closest approach
2026-10-17 08:20 UTC
Relative speed
1.76 km/s
Altitude
Last confirmed
17 Oct 08:11 UTC
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US USA 81 and ESA SENTINEL 2A were predicted to reach a closest approach of 6.13 km at 2026-10-17 08:20 UTC, at a relative speed of 1.76 km/s. Final forecast, made 9 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 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
USA 81Payload
NORAD 21949
CountryUS
Launched1992-04-25
COSPAR1992-023A
Maneuver capableUnknown
NORAD 40697
CountryESA
Launched2015-06-23
COSPAR2015-028A
Maneuver capableUnknown

Where This Happens

Altitude context
DEBRIS BELT 700–1000 KM2006001,0001,5002,000 kmTHIS PASS · 789 KMISS 420Starlink 550

At 789 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 · USA 81 ⟷ SENTINEL 2A
2026-10-17 08:206.13 km Final forecast1.76 km/s789 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.

These Objects Elsewhere

Other screened approaches · 7 days
4.30 km10-16 17:57 UTC
USA 81FENGYUN 1C DEB
5.02 km10-21 10:43 UTC
USA 81SL-16 DEB
6.16 km10-17 23:31 UTC
USA 81NOAA 16 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 — “USA 81 ⟷ SENTINEL 2A: 6.13 km predicted close approach”, https://orbitalradar.com/conjunction/21949-40697 (accessed 2026-10-21).