Samos 4


Samos 4 was an American reconnaissance satellite which was lost in a launch failure in 1961.[1] 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 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 of 1.67 metres (5 ft 6 in), and a resolution of 1.5 metres (4 ft 11 in).[2]

Samos 4
Mission typeReconnaissance
OperatorUS Air Force
Mission duration15-30 days (planned)
Failed to orbit
Spacecraft properties
Spacecraft typeSamos-E5
Start of mission
Launch date22 November 1961, 20:45:47 (1961-11-22UTC20:45:47Z) UTC
RocketAtlas LV-3A Agena-B 108D
Launch sitePoint Arguello LC-1-1
Orbital parameters
Reference systemGeocentric
RegimeSun-synchronous low Earth

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.[3] 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.[4] Samos 4 was to have operated in a Sun-synchronous low Earth orbit. It was designed to operate for between 15 and 30 days.[2]


  1. ^ Wade, Mark. "Samos". Encyclopedia Astronautica. Archived from the original on 16 January 2010. Retrieved 17 June 2010.
  2. ^ a b Krebs, Gunter. "Samos E-5". Gunter's Space Page. Retrieved 17 June 2010.
  3. ^ McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved 17 June 2010.
  4. ^ McDowell, Jonathan. "SAMOS 4". The History of Spaceflight. Jonathan's Space Page. Retrieved 17 June 2010.