Mariner 10 on board an Atlas-Centaur Rocket

Because Mariner 10 used gravity assist to reach Mercury, NASA was able to launch it using an Atlas-Centaur rocket instead of a larger and more expensive rocket.

Caption:
Mariner 10 on board an Atlas-Centaur Rocket.
Type: Photograph
Image Date: November 3, 1973
Credit: Courtesy of Jet Propulsion Laboratory
Origin: Jet Propulsion Laboratory
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Mariner 10 on board an Atlas-Centaur Rocket.