| Primary satellite | Secondary satellite |
| Name | Cosmos 858 Rocket | ERS 2 DEB |
| Spacetrack catalog number | 9444 | 31137 |
| Radar cross section | large | small |
| Epoch of two-line elements (UTC) | 2021 Jan 23 17:46 | 2021 Jan 23 20:51 |
| Time of closest approach (UTC) | 2020 Dec 03 20:58:12.716 |
| Minimum distance | 2.883 km |
| Height difference | 1.573 km |
| Relative speed | 14.856 km/s |
| Angle between velocity vectors | 168° |
| Geographic position | 49.5°S, 81.6°E |
| Height | 774 km |
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