Vela 4A

Vela 4A (also known Vela 7 and OPS 6638 ) was an American reconnaissance satellite to detect explosions and nuclear tests on land and in space. It was released together with Vela 4B, ERS 18, OV5 1 and OV5 3.

The ship remains in orbit around Earth.

Instruments

 * 2 optical bhangmeters observing Earth
 * 12 external X-ray detectors
 * 18 internal neutron and gamma-ray detectors