The Injun program was a series of six satellites designed and built by researchers at the University of Iowa. They were intended to observe various radiation and magnetic phenomena in the ionosphere and beyond.
The design specifics of the satellites had little in common, though all were solar-powered and the first five used magnetic stabilization to control spacecraft attitude. (The last in the series was spin-stabilized.) Instruments included particle detectors of varying types, magnetometers, and photometers for observing auroras. The last three satellites were launched as part of the Explorer program.
In spite of various hardware difficulties and the loss of Injun 2 due to an upper stage failure, the program was generally successful. In particular they produced data on the radiation aftereffects of the Starfish Prime high-altitude nuclear test.
| Name | Also known as | Launched | Vehicle | Ceased operation | Notes |
|---|---|---|---|---|---|
| Injun 1 | June 29, 1961 | Thor-Able | March 6, 1963 | Failed to separate from Solrad 3; still in orbit[1] | |
| Injun 2 | January 24, 1962 | Thor-Able | failed at launch | Upper stage produced insufficient thrust | |
| Injun 3 | December 12, 1962 | Thor-Agena | August 25, 1968 | ||
| Injun 4 | IE B, Explorer 25 | November 21, 1964 | Scout X-4 | December 1966 | still in orbit[2] |
| Injun 5 | IE C, Explorer 40 | August 8, 1968 | Scout X-4 | June 1971 | still in orbit |
| Injun 6 | IE D, Hawkeye, Explorer 52, Neutral Point Explorer | June 3, 1974 | Scout X-4 | April 28, 1978 | main article: Explorer 52 |