Mariner 10 Reaches Mercury
Next: March 29, 2027
The first visit to the innermost planet.
The story
Where it comes from
On 29 March 1974 NASA's Mariner 10 flew 703 kilometres above Mercury, becoming the first spacecraft to visit the planet closest to the Sun, and this Story marks the anniversary. Launched from Cape Canaveral on 3 November 1973, it first passed Venus and used that planet's gravity to bend its path towards Mercury, the first time a spacecraft had used a gravity assist. As it approached, its cameras showed a cratered, Moon-like surface that no one had seen before.
How it's celebrated
There is no organised observance. It is a good day to look through Mariner 10's photographs, read about the gravity assist it was the first to use, or follow BepiColombo, the European and Japanese mission to Mercury named after one of Mariner 10's planners.
Did you know
- Giuseppe 'Bepi' Colombo of the University of Padua worked out an orbit that brought Mariner 10 back to Mercury every 176 days, so it flew past three times in 1974 and 1975.
- Its data revealed a surprising magnetic field and a metal core making up about 80 per cent of Mercury's mass, and no spacecraft returned for more than 30 years.
- BepiColombo is a joint mission of the European Space Agency and Japan's JAXA, which built Mio, the orbiter studying Mercury's magnetic environment.
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