Samos 4 was an American

reconnaissance satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The ...

which was lost in a launch failure in 1961. It was a film-return reconnaissance spacecraft, meaning that it returned images in a film capsule at the end of its mission. It was operated as part of the

Samos Samos (, also ; el, Σάμος ) is a Greek island in the eastern Aegean Sea, south of Chios, north of Patmos and the Dodecanese, and off the coast of western Turkey, from which it is separated by the -wide Mycale Strait. It is also a separate ...

programme. Samos 4 was the first of three Samos-E5 spacecraft to be launched; Samos-E5 satellites were based on an Agena-B, and carried a camera with a

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

of , and a resolution of . The launch of Samos 4 occurred at 20:45:47 UTC on 22 November 1961. An Atlas LV-3A Agena-B rocket was used, flying from Launch Complex 1-1 at the Point Arguello Naval Air Station. Four minutes and four seconds into the flight, the rocket's first stage attitude control system malfunctioned, and control over the rocket's pitch was lost. The rest of the flight proceeded nominally, but, by the time the second stage ignited, it had pitched up by 160 degrees and was hence facing in the wrong direction. Its three-minute-41-second burn reduced the vehicle's velocity instead of increasing it, and as a result the satellite failed to achieve orbit. Samos 4 was to have operated in a Sun-synchronous

low Earth orbit A low Earth orbit (LEO) is an orbit around Earth with a period of 128 minutes or less (making at least 11.25 orbits per day) and an eccentricity less than 0.25. Most of the artificial objects in outer space are in LEO, with an altitude never mor ...

. It was designed to operate for between 15 and 30 days.

References

{{Orbital launches in 1961 Spacecraft launched in 1961 Satellite launch failures