| Primary satellite | Secondary satellite |
| Name | Vanguard 1 Rocket | COSMOS 2251 DEB |
| Spacetrack catalog number | 16 | 35019 |
| Radar cross section | medium | small |
| Epoch of two-line elements (UTC) | 2021 Mar 03 11:58 | 2021 Mar 02 07:37 |
| Time of closest approach (UTC) | 2021 Jan 30 03:36:14.391 |
| Minimum distance | 31.076 km |
| Height difference | 3.468 km |
| Relative speed | 11.031 km/s |
| Angle between velocity vectors | 89° |
| Geographic position | 30.3°N, 157.8°E |
| Height | 655 km |
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