COSMOS 2612 (SSC.68762) walks up to ICEYE-X36 (SSC.59103) In July we posted on the Cosmos 2609–2614 group. Back then we flagged COSMOS 2612 as the satellite best placed to reach ICEYE-X36. Three months later, it did. Analysis via COMSPOC SSA. On 1 October COSMOS 2612 raised its orbit ~47 km. The higher orbit gave it a fast catch-up drift, and it passed ICEYE-X36 at ~55 km on 5 October and again on 12 October. Within about two hours of the second pass it made two retrograde burns (~27 m/s total) and dropped back to ICEYE-X36’s altitude, ~515 km behind it. Between 13 and 16 October seven small burns (~5 m/s total) closed that gap. By 16 October COSMOS 2612 was in ICEYE-X36’s plane (within 0.003°) and at its altitude. Since the two share a plane, there are no plane crossings to wait for. From 16–18 October they spent ~24 hours within 2 km of each other and ~12 hours within 1 km. First pass was ~220 m (max uncertainty ~490 m) near 14:03 UTC on 16 October. It then held 2–4 km behind before drawing level on 17 October and settling into a centred safety ellipse around ICEYE-X36, which it held for the rest of the day. Closest pass in our solution was ~60 m (max uncertainty ~950 m) near 14:18 UTC. By late on 17 October it had drifted ~2 km ahead, then trimmed back for a third pass at ~260 m (max uncertainty ~160 m) near 01:58 UTC on 18 October. Relative speed at the closest points was 0.15–0.9 m/s, walking pace or slower. Slow walk-past, not a fly-by . ICEYE-X36 did not maneuver. COSMOS 2612 burned away at 12:30 UTC on 18 October, braked on 19 October, and is now holding ~480 km from ICEYE-X36 in the same orbit. We’ve seen this sequence before. COSMOS 2581, 2582 and 2583 (SSC.62902/62903/62904) have been running it against each other since February 2025: raise, phase, drop to co-altitude, close at under half a meter per second, hold, depart, loiter. Since August 2025 we’ve logged more than 170 sub-km conjunction events within that trio, several down to single-digit meters. Until now, every target had been one of their own. This is the first non-cooperative one. @planet4589 @shell_jim @IntegrityISR @ObservableSpace

Quick Update on SJ-31 SJ-31 (SSC.69570) launched 16 Jun from Xichang with a stated mission of space environment detection. Its orbit is Molniya-like, but the high point sits near the equator ~4,100 km above the GEO belt and slowly walks past every GEO longitude. It looks down on the belt without entering it. Where it crosses the equator it stays more than 3,100 km outside equatorial GEO belt with a 2.82 km/s speed difference, so there is no close-approach case. At 28 Sep 12:00 UTC, its apogee was 39,918 km, with 63.5° inclination, 0.69 eccentricity, and 172.0° argument of perigee. The orbit has not changed in the past two weeks. Visualization video includes SJ-31 in inertial frame and example GEO US assets in fixed frame.