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Mariner 10
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Mariner 10
Mariner 10 Mission to Mercury Mariner 10 Mission to Venus

Goals: Mariner 10 was the first spacecraft sent to study Mercury. Mariner 10 also studied Venus while using the planet's gravity to modify its speed and trajectory, enabling it to reach Mercury.

Accomplishments: Mariner 10 was the only mission to Mercury until NASA's MESSENGER mission more than 30 years later. It was also the first spacecraft to reach one planet by using the gravity of another planet (in this case, Venus) to alter its speed and trajectory. This has become an extremely important technique.

During three flybys of Mercury, Mariner 10 photographed half the planet's moonlike surface and transmitted data indicating a surprising magnetic field, a metallic core comprising about 80 percent of the planet's mass, and temperatures ranging from 187°C on the dayside to -183°C on the nightside.


Key Dates
3 Nov 1973:  Launch (05:45 UT)
5 Feb 1974:  Venus Encounter
29 Mar 1974:  Mercury Flyby 1
21 Sep 1974:  Mercury Flyby 2
16 Mar 1975:  Mercury Flyby 3
Status: Successful
Fast Facts
Mariner 10 Facts Mariner 10 was a mission of many firsts.

It was the first spacecraft to visit Mercury (right), the first to use a gravity assist and the first to visit more than one planet.

It was also the first to make multiple flybys of a planet (Mercury) and the first to use the solar wind for orientation during flight.
People Spotlight
Al Hibbs Al Hibbs
Al Hibbs decided as a five-year-old that he wanted to go to the Moon. He did qualify as an astronaut, but his legacy is in robotic exploration. Read More...
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Last Updated: 5 Mar 2015