Mariner 10 Spacecraft

Launched in 1973, Mariner 10 used the gravity of Venus to propel it to Mercury with a minimal use of fuel. 

To reach Mercury, Mariner 10 first passed by Venus, threading through a narrow 400-kilometer (250-mile) “window” of space a few thousand kilometers above the surface. That level of accuracy had not been possible with the navigation systems available for the Pioneer 4 mission in 1959. After a gravitational assist from Venus, Mariner 10 entered an orbit around the Sun that allowed it to pass by Mercury three times in 1974 and 1975.

Caption:
Launched in 1973, Mariner 10 used the gravity of Venus to propel it to Mercury with a minimal use of fuel.
Type: Illustration
Image Date: ca. 1973
Credit: National Aeronautics and Space Administration via National Air and Space Museum, Smithsonian Institution
Origin: National Aeronautics and Space Administration, National Air and Space Museum, Smithsonian Institution
NASA-73-H-1028 (5A23516)
Innovations
Navigation Methods
 
Launched in 1973, Mariner 10 used the gravity of Venus to propel it to Mercury with a minimal use of fuel.