EXPLORER 28
| Launched | 28 May 1965 |
| Flight ended | 3 July 1968 |
| Status | Decayed |
| Launch site | Air Force Eastern Test Range, Florida, USA |
| Owner | United States |
| NORAD ID | 1388 |
| COSPAR ID | 1965-042A |
| Alternative names |
IMP-3 |
| Observing |