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| Ranger 1 launch cover with Swanson cachet, postmarked at Patrick Air Force Base, August 23, 1961. |
From August 1961 to January 1964, the United States launched a series of Ranger spacecraft aimed at capturing close-up photographs of the lunar surface, though these efforts were largely unsuccessful. Ranger 1, launched on August 23, 1961, was the first U.S. spacecraft designed to test the feasibility of entering a parking orbit around Earth before proceeding to the Moon.
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| Photo: The Ranger 1 spacecraft. |
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| Zaso cover with a paste-on cachet of Ranger 1, postmarked at Port Canaveral, August 23, 1961. |
A parking orbit allows engineers to calculate a more precise trajectory for the spacecraft's journey to the Moon. Ranger 1 successfully entered a low Earth orbit, but its engines, intended to re-ignite after 13 minutes and burn for 90 seconds, only fired for a few seconds before shutting off. The spacecraft ultimately re-entered Earth's atmosphere after completing 111 orbits.
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| Photo: Launch of Ranger 1 on August 23, 1961. |
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| Photo: A diagram illustrating the trajectory of Ranger to the Moon. |
(Reference from
Ranger 1)
