| Primary satellite | Secondary satellite |
| Name | Cosmos 1666 | PSLV DEB |
| Spacetrack catalog number | 15889 | 27583 |
| Radar cross section | large | small |
| Epoch of two-line elements (UTC) | 2021 Jan 15 20:53 | 2021 Jan 15 20:29 |
| Time of closest approach (UTC) | 2020 Dec 04 08:09:17.849 |
| Minimum distance | 6.772 km |
| Height difference | -2.015 km |
| Relative speed | 15.204 km/s |
| Angle between velocity vectors | 180° |
| Geographic position | 72.3°N, 137.9°E |
| Height | 529 km |
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