| Primary satellite | Secondary satellite |
| Name | Vanguard 2 | COSMOS 2251 DEB |
| Spacetrack catalog number | 11 | 34303 |
| Radar cross section | medium | small |
| Epoch of two-line elements (UTC) | 2025 Dec 15 15:37 | 2025 Dec 15 21:22 |
| Time of closest approach (UTC) | 2024 Nov 10 21:37:50.316 |
| Minimum distance | 3138.271 km |
| Height difference | -1627.161 km |
| Relative speed | 11.384 km/s |
| Angle between velocity vectors | 111° |
| Geographic position | 12.9°S, 42.8°W |
| Height | 2452 km |
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