Agena A

Agena was also considered one of the nation's most versatile space vehicles. It served as the upper stage power plant for the Air Force's Atlas and Thor missiles. The original Agena vehicle, identified as Agena A, was custom built to the specifications of each mission. It measures approximately 19 feet in length and 5 feet in diameter. Agena A probed the reliability and soundness of the all-purpose vehicle concept and led to the development of the Agena B.

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