|Operator||United States Air Force|
|Harvard designation||1961 Alpha 1|
|Mission duration||1 month|
|Start of mission|
|Launch date||January 31, 1961, 20:31:19UTC|
|Rocket||Atlas LV-3A Agena-A 70D|
|Launch site||Point Arguello LC-1-1|
|End of mission|
|Decay date||October 21, 1973|
|Regime||Sun-synchronous Low Earth|
|Perigee||474 kilometers (295 mi)|
|Apogee||553 kilometers (344 mi)|
Samos 2 was an American reconnaissance satellite launched in 1961 as part of the Samos program. It was an early electro-optical reconnaissance spacecraft, meaning that it transmitted images to receiving stations on Earth rather than returning them in a film capsule. Samos 2 was a Samos-E1 spacecraft, based on an Agena-A.
The launch of Samos 2 occurred at 20:31:19 UTC on January 31, 1961. An Atlas LV-3A Agena-A rocket was used, flying from Launch Complex 1-1 at the Point Arguello Naval Air Station. Ten minutes and fourteen seconds later, the Agena's engine cut off, having successfully achieved a low Earth orbit. It was assigned the Harvard designation 1961 Alpha 1.
Samos 2 operated in a Sun-synchronous low Earth orbit, with an apogee of 553 kilometres (344 mi), a perigee of 474 kilometres (295 mi), an inclination of 97.4 degrees, and a period of 94.9 minutes. The satellite had a mass of 1,915 kilograms (4,222 lb), and measured 6.86 metres (22.5 ft) in length, with a diameter of 1.52 metres (5 ft 0 in). It operated successfully, however the images returned were poor. Designed to operate for around ten days, it ceased operations around a month after launch, and decayed from orbit on October 21, 1973.
- Krebs, Gunter. "Samos E-1". Gunter's Space Page. Retrieved June 17, 2010.
- McDowell, Jonathan. "Launch Log". Jonathan's Space Page. Retrieved June 17, 2010.
- McDowell, Jonathan. "SAMOS 2". The History of Spaceflight. Jonathan's Space Page. Retrieved June 17, 2010.
- McDowell, Jonathan. "Satellite Catalog". Jonathan's Space Page. Retrieved June 17, 2010.
- "Pioneer/Samos-A". FAS. Retrieved June 17, 2010.
- Wade, Mark. "Samos". Encyclopedia Astronautica. Retrieved June 17, 2010.