| Primary satellite | Secondary satellite |
| Name | NUDT-PHONESAT | COSMOS 2251 DEB |
| Spacetrack catalog number | 40900 | 36042 |
| Radar cross section | small | small |
| Epoch of two-line elements (UTC) | 2021 Feb 25 12:39 | 2021 Feb 25 13:24 |
| Time of closest approach (UTC) | 2021 Jan 18 05:35:48.617 |
| Minimum distance | 325.814 km |
| Height difference | 5.098 km |
| Relative speed | 14.684 km/s |
| Angle between velocity vectors | 149° |
| Geographic position | 64.9°S, 4.4°W |
| Height | 509 km |
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