Explorer-4 ( Eng. Explorer-IV - Researcher) is an American artificial Earth satellite (AES), launched on July 26, 1958 . The satellite was intended to study the Earth's radiation belts and the effect of nuclear explosions on these belts.
| Explorer 4 | |
|---|---|
| Explorer IV | |
 The satellite Explorer-4 | |
| Manufacturer |  Jpg |
| Operator | Abma |
| Tasks | Earth exploration |
| Satellite | Of the earth |
| Launch pad | Cape Canaveral |
| Launch vehicle | Jupiter-S |
| Launch | July 26, 1958 15:07 UTC |
| Flight duration | 454 days |
| Number of turns | about 5930 |
| Descent from orbit | October 23, 1959 |
| NSSDC ID | 1958-005A |
| SCN | 00009 |
| Specifications | |
| Weight | 25.5 kg |
| Elements of the orbit | |
| Semimajor axis | 7616.2 km |
| Eccentricity | 0.127936 |
| Mood | 50.3 ° |
| Circulation period | 110.2 min |
| Apocenter | 2213 km |
| Pericenter | 263 km |
The equipment consisted of two Geiger-Muller sensors and two transmitters. Sensors and transmitters stopped working in September-October 1958 due to premature depletion of on-board batteries.