| Primary satellite | Secondary satellite |
| Name | Cosmos 1821 Rocket | Kosmos-755 |
| Spacetrack catalog number | 17526 | 8072 |
| Radar cross section | large | large |
| Epoch of two-line elements (UTC) | 2021 Jan 23 19:53 | 2021 Jan 23 14:25 |
| Time of closest approach (UTC) | 2020 Nov 30 10:54:04.948 |
| Minimum distance | 36.304 km |
| Height difference | 1.980 km |
| Relative speed | 3.358 km/s |
| Angle between velocity vectors | 26° |
| Geographic position | 82.8°S, 158.6°W |
| Height | 1017 km |
|