Mariner program
Between 1962 and late 1973, NASA's Jet Propulsion Laboratory (JPL) designed and built 10 robotic interplanetary probes named Mariner to explore the inner Solar System – visiting the planets Venus, Mars and Mercury for the first time, and returning to Venus and Mars for additional close observations.
Later Mariner-based spacecraft include Galileo and Magellan, while the second-generation Mariner Mark II series evolved into the Cassini–Huygens probe.
[4] The Mariner program began in 1960 with a series of JPL mission studies for small-scale, frequent exploration of the nearest planets.
[1] The name of the Mariner program was decided in "May 1960 – at the suggestion of Edgar M. Cortright" to have the "planetary mission probes ... patterned after nautical terms, to convey 'the impression of travel to great distances and remote lands.'"
JPL engineers proposed to make the Mariners "three-axis-stabilized," meaning that unlike other space probes they would not spin.
[1] All Mariner spacecraft were based on a hexagonal or octagonal bus, which housed all of the electronics, and to which all components were attached, such as antennae, cameras, propulsion, and power sources.
On the way it measured for the first time the solar wind, a constant stream of charged particles flowing outward from the Sun.
The pictures, played back from a small tape recorder over a long period, showed lunar-type impact craters (just beginning to be photographed at close range from the Moon), some of them touched with frost in the chill Martian evening.
It carried a complement of experiments to probe Venus' atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet.
By chance, both flew over cratered regions and missed both the giant northern volcanoes and the equatorial grand canyon discovered later.
Its launch mass was nearly doubled by the onboard rocket propellant needed to thrust it into orbit around Mars, but otherwise it closely resembled its predecessors.
[1] It entered Martian orbit in November 1971 and began photographing the surface and analyzing the atmosphere with its infrared and ultraviolet instruments.
Mariner Jupiter-Saturn was approved in 1972 after the cancellation of the Grand Tour program, which proposed visiting all the outer planets with multiple spacecraft.
The Mariner Jupiter-Saturn program proposed two Mariner-derived probes that would perform a scaled back mission involving flybys of only the two gas giants, though designers at JPL built the craft with the intention that further encounters past Saturn would be an option.
