| Primary satellite | Secondary satellite |
| Name | Vanguard 1 | COSMOS 2251 DEB |
| Spacetrack catalog number | 5 | 40228 |
| Radar cross section | small | small |
| Epoch of two-line elements (UTC) | 2025 Jun 18 18:37 | 2025 Jun 19 10:34 |
| Time of closest approach (UTC) | 2025 May 21 09:44:51.644 |
| Minimum distance | 33.585 km |
| Height difference | -1.659 km |
| Relative speed | 12.533 km/s |
| Angle between velocity vectors | 107° |
| Geographic position | 9.4°S, 108.1°W |
| Height | 750 km |
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