Mariner 10
Launch Date Nov. 3, 1973
Launch Site Cape Canaveral, Florida, USA
Destination Mercury, Venus
Type Flyby
Status Successful
Nation United States
Alternate Names 1973-085A, Mariner-J, Mariner Venus/Mercury 73, 06919


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.


Mariner 10 was the only mission to Mercury until NASA's MESSENGER mission more than 30 years later. On its way to Mercury, Mariner 10 became the first spacecraft to use the gravity of one planet (in this case, Venus) to reach another. This has become an extremely important technique. While flying by Venus, the spacecraft took ultraviolet pictures that revealed great bands of clouds, providing data on atmospheric circulation which included upper-atmosphere wind speeds of 300 km/hr.

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 degrees Celsius on the dayside to -183 degrees Celsius on the nightside.

Mariner 10
This photo identifies the spacecraft's science instruments, which were used to study the atmospheric, surface and physical characteristics of Venus and Mercury. This was the sixth in the series of Mariner spacecraft that explored the inner planets beginning in 1962. Image Credit: NASA/JPL

Key Dates

Nov. 3, 1973: Launch

Feb. 5. 1974: Venus Encounter

Mar. 29, 1974: Mercury Flyby 1

Sept. 21, 1974: Mercury Flyby 2

Mar. 16, 1975: Mercury Flyby 3


Launch Vehicle: Atlas-Centaur

Spacecraft Mass: 474 kilograms

Spacecraft Instruments:

  1. imaging system
  2. infrared radiometer
  3. ultraviolet airglow spectrometer
  4. ultraviolet occultation spectrometer
  5. two magnetometers
  6. charged-particle telescope
  7. plasma analyzer

Additional Resources

National Space Science Data Center Master Catalog: Mariner 10

Selected References

Siddiqi, Asif A. Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, NASA, 2002.

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