Launched in 1973, it was the first spacecraft to visit two planets and use another planet's gravity to boost its speed.
It took detailed photographs of about half of Mercury's surface and the first close-ups of Venus.
Until the Messenger probe, launched in 2004, Mariner 10's Mercury photographs were the best available.
Photo: Mariner 10's first image of Mercury (NASA/JPL/USGS)
The first two-planet mission reaches Mercury.
Sir Patrick Moore talks to Dr David Rothery about Messenger's Mercury images.
The Messenger probe is looking at the side of Mercury that Mariner 10 couldn't photograph and is studying the planet's magnetic field and dense core. Having now completed a series of flybys, in 2011 it will enter a yearlong orbit of the planet.
Mariner 10 was an American robotic space probe launched by NASA on November 3, 1973, to fly by the planets Mercury and Venus.
Mariner 10 was launched approximately two years after Mariner 9 and was the last spacecraft in the Mariner program. (Mariner 11 and 12 were allocated to the Voyager program and redesignated Voyager 1 and Voyager 2.)
The mission objectives were to measure Mercury's environment, atmosphere, surface, and body characteristics and to make similar investigations of Venus. Secondary objectives were to perform experiments in the interplanetary medium and to obtain experience with a dual-planet gravity assist mission. Mariner 10's science team was led by Bruce C. Murray at the Jet Propulsion Laboratory.