Mariner Program

Occurred 50 years ago

Type

Flybys, Orbiters

Duration

1962-1975

Targets

Mars, Venus, and Mercury

results

Successful

The 10 Mariners visited Venus, Mars and Mercury for the first time, and later returned to Venus and Mars for a closer look. The final mission in the series, Mariner 10, flew past Venus before going on to Mercury for a total of three flybys. Mariner 9 became the first spacecraft to orbit another planet when it reached Mars in 1971.

Spacecraft
Launch Date
Objective
Results
Jul 22, 1962
Venus flyby
Unsuccessful
Aug 27, 1962
Venus flyby
Successful
Nov 5, 1964
Mars flyby
Unsuccessful
Nov 28, 1964
Mars flyby
Successful
Jun 14, 1967
Venus flyby
Successful
Feb 25, 1969
Mars flyby
Successful
Mar 27, 1969
Mars flyby
Successful
May 9, 1971
Mars orbit
Unsuccessful
May 30, 1971
Mars orbit
Successful
Nov 3, 1973
Venus, Mercury flybys
Successful

The Mariners were a series of twin spacecraft . Each launched on a different rocket in case of problems with the other. Mariner 1, Mariner 3, and Mariner 8 werfocused on small-scale, frequent exploration of the nearest planets.e lost during launch, but their backups were successful. All remaining Mariners completed their scientific missions.

Illustrated diagram of the Atlas-Agena rocket and Mariner spaecraft combination.
A diagram of an early series Mariner spacecraft and launch vehicle. Mariner spacecraft explored Mercury, Venus and Mars.
NASA/JPL-Caltech

What did we learn from the Mariner missions?

  • Engineers learned that interplanetary exploration was workable with small, low-cost spacecraft. Missions could be developed in a few years and survive in space for a few years.
  • Scientists learned a great deal about the surfaces of Mars and Mercury. They gathered new details about the atmospheres of Mars and Venus and the solar system. All three planets visited proved to be very different from Earth.
  • Venus, whose surface is not visible from space, had a dense carbon dioxide atmosphere. Clouds covering a hot surface made it even hotter by the atmosphere’s “greenhouse effect.”
  • Mercury, not quite so hot as Venus, had an airless, cratered surface like the Moon,
  • Mariner 9 revealed great volcanoes and valleys on Mars. It found the planet had a very thin, cold atmosphere, mostly of carbon dioxide.

Mariners laid the groundwork for all the deep space exploration missions that followed.

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