| Primary satellite | Secondary satellite |
| Name | Cosmos 1821 Rocket | FENGYUN 1C DEB |
| Spacetrack catalog number | 17526 | 38122 |
| Radar cross section | large | small |
| Epoch of two-line elements (UTC) | 2021 Jan 23 19:53 | 2021 Jan 23 00:55 |
| Time of closest approach (UTC) | 2020 Nov 30 18:47:42.101 |
| Minimum distance | 2.939 km |
| Height difference | -1.665 km |
| Relative speed | 14.597 km/s |
| Angle between velocity vectors | 170° |
| Geographic position | 78.9°N, 34.4°W |
| Height | 980 km |
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