The Injun program was a series of six satellites designed and built by researchers at the University of Iowa 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.[1] The last three satellites were launched as part of the Explorer program of the NASA.
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 Van Allen radiation belts including electrical convection in the magnetosphere,[2] and the radiation after effects of the Starfish Prime high-altitude nuclear test.[3]
| Name | Also known as | Launched | Vehicle | Ceased operation | Notes | |
|---|---|---|---|---|---|---|
| Injun 1 | 29 June 1961 | Thor-Able | 6 March 1963 | Failed to separate from Solrad 3; still in orbit.[4] | ||
| Injun 2 | 24 January 1962 | Thor-Able | Failed to orbit | Upper stage produced insufficient thrust. | ||
| Injun 3 | 12 December 1962 | Thor-Agena | 25 August 1968 | Deorbited on 25 August 1968. | ||
| Injun 4 | IE-B, Explorer 25 | 21 November 1964 | Scout X-4 | December 1966 | Still in orbit.[5] | |
| Injun 5 | IE-C, Explorer 40 | 8 August 1968 | Scout X-4 | June 1971 | Still in orbit.[6] | |
| Injun 6 | IE-D, Hawkeye, Neutral Point Explorer, Explorer 52 | 3 June 1974 | Scout X-4 | 28 April 1978 | Main article: Explorer 52 | |