Mariner program

The Mariner series of spacecraft were interplanetary probes designed to investigate Mars, Venus, and Mercury. The program included a number of firsts, including the first planetary flyby, the first planetary orbiter, and the first gravity assist.

Of the ten vehicles in the Mariner series, seven were successful and the other three were lost. The planned Mariner 11 and 12 vehicles evolved into Voyager 1 and Voyager 2.

Mariner 1 and Mariner 2 - As the first spacecraft to fly by another planet, Mariner 2 was built as a backup to Mariner 1, which failed shortly after launch to Venus. The Mariner 2 spacecraft was launched on August 27, 1962, sending it on a 3½-month flight to Venus.

• Mission: Venus flyby
• Mass: 203 kg (446 lb)
• Sensors: microwave and infrared radiometers, cosmic dust, solar plasma and high-energy radiation, magnetic fields

Mariner 3 and Mariner 4 - The Mariner 4 spacecraft gave the first glimpse of Mars at close range. Launched on November 28, 1964, Mariner 4 was the fourth in a series of spacecraft used for planetary exploration in a flyby mode and represented the first successful flyby of the planet Mars. A sister ship, Mariner 3, was launched three weeks earlier than Mariner 4, but was lost when the launch vehicle's nose fairing failed to jettison.

• Mission: Mars flyby
• Mass: 261 kg (575 lb)
• Sensors: camera with digital tape recorder (about 20 pictures), cosmic dust, solar plasma, trapped radiation, cosmic rays, magnetic fields, radio occultation and celestial mechanics

Mariner 5 - The Mariner 5 spacecraft launched to Venus on June 14, 1967 and arrived in the vicinity of the planet in October 1967. Mariner 5 carried a complement of experiments to probe Venus's atmosphere with radio waves, scan its brightness in ultraviolet light, and sample the solar particles and magnetic field fluctuations above the planet.

• Mission: Venus flyby
• Mass: 245 kg (540 lb)
• Sensors: ultraviolet photometer, cosmic dust, solar plasma, trapped radiation, cosmic rays, magnetic fields, radio occultation and celestial mechanics

Mariner 6 and 7 - Mariners 6 and 7 were identical teammates in a two-spacecraft mission to Mars. Mariners 6 and 7 were designed to fly over the equator and southern hemisphere of the planet Mars. Mariner 6 was launched on February 24, 1969, followed by Mariner 7 on March 27, 1969.

• Mission: Mars flybys
• Mass 413 kg (908 lb)
• Sensors: wide- and narrow-angle cameras with digital tape recorder, infrared spectrometer and radiometer, ultraviolet spectrometer, radio occultation and celestial mechanics

Mariner 8 and Mariner 9 - The first artificial satellite of Mars was Mariner 9, launched in May 1971. In November 1971, the spacecraft entered Martian orbit and began photographing the surface and analyzing the atmosphere with its infrared and ultraviolet instruments. The mission originally consisted of two spacecraft designed to simultaneously map the Martian surface, but the identical Mariner 8 vehicle was lost in a launch vehicle failure.

• Mission: orbit Mars
• Mass 998 kg (2,200 lb)
• Sensors: wide- and narrow-angle cameras with digital tape recorder, infrared spectrometer and radiometer, ultraviolet spectrometer, radio occultation and celestial mechanics

Mariner 10 - The Mariner 10 spacecraft launched on November 3, 1973. Mariner 10 was the first spacecraft to use a gravity assist trajectory, accelerating as it entered the gravitational influence of Venus, then being flung by the planet's gravity onto a slightly different course to reach Mercury. It was also the first spacecraft to encounter two planets at close range.

• Mission: Venus and Mercury flybys
• Mass: 433 kg (952 lb)
• Sensors: twin narrow-angle cameras with digital tape recorder, ultraviolet spectrometer, infrared radiometer, solar plasma, charged particles, magnetic fields, radio occultation and celestial mechanics