| Primary satellite | Secondary satellite |
| Name | First-Move | COSMOS 2251 DEB |
| Spacetrack catalog number | 39439 | 38221 |
| Radar cross section | small | small |
| Epoch of two-line elements (UTC) | 2021 Feb 25 22:00 | 2021 Feb 21 11:00 |
| Time of closest approach (UTC) | 2021 Jan 20 10:12:52.531 |
| Minimum distance | 72.287 km |
| Height difference | -4.413 km |
| Relative speed | 4.127 km/s |
| Angle between velocity vectors | 32° |
| Geographic position | 42.2°N, 72.7°W |
| Height | 666 km |
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