Launch Date: July 21, 1962
As plans were getting under way to explore the Moon with the Rangers and Surveyors, JPL and NASA also turned their attention to the rest of the solar system. The Mariner series of missions were designed to be the first U.S. spacecraft to other planets, specifically Venus and Mars. Mariner 1 and 2 were nearly identical spacecraft developed to fly by Venus. The rocket carrying Mariner 1 went off-course during launch on July 22, 1962, and was blown up by a range safety officer about 5 minutes into flight.
A month later, Mariner 2 was launched successfully on August 27, 1962, sending it on a 3-1/2-month flight to Venus. On the way it measured for the first time the solar wind, a constant stream of charged particles flowing outward from the Sun. It also measured interplanetary dust, which turned out to be more scarce than predicted. In addition, Mariner 2 detected high-energy charged particles coming from the Sun, including several brief solar flares, as well as cosmic rays from outside the solar system. As it flew by Venus on December 14, 1962, Mariner 2 scanned the planet with infrared and microwave radiometers, revealing that Venus has cool clouds and an extremely hot surface. (Because the bright, opaque clouds hide the planet’s surface, Mariner 2 was not outfitted with a camera.) Mariner 2's signal was tracked until January 3, 1963. The spacecraft remains in orbit around the Sun.
Mariner 3 was a 260 kg solar-cell and battery-powered spacecraft designed to make scientific measurements in the vicinity of Mars and to obtain photographs of the planet's surface and transmit these to Earth. It was intended that the spacecraft would encounter Mars after a 325-million mile journey in a little less than 8 months. A protective shield failed to eject after the spacecraft had passed through the atmosphere. None of the instrument sensors were uncovered, and the added weight prevented the spacecraft from attaining its prescribed Mars trajectory.
Mariner 4 was the first spacecraft to get a close look at Mars. Flying as close as 9,846 kilometers (6,118 miles), Mariner 4 revealed Mars to have a cratered, rust-colored surface, with signs on some parts of the planet that liquid water had once etched its way into the soil. In addition to various field and particle sensors and detectors, the spacecraft had a television camera, which took 22 television pictures covering about 1% of the planet. Initially stored on a 4-track tape recorder, these pictures took four days to transmit to Earth.
Mariner 5 was originally built to be the backup for Mariner 4 to Mars, but was never needed for that purpose. Thus, it was refurbished and modified to go to Venus instead. It flew by Venus at a distance of 3,990 kilometers (2,480 miles), and with its more sensitive instruments than aboard Mariner 2, revealed new information about Venus' atmosphere, including its composition of 85-99% carbon dioxide. Mariner 5 also studied the interplanetary space in the vicinity of Venus and furthered the art and science of building and operating interplanetary spacecraft.
Mariners 6 and 7 were identical teammates in a two-spacecraft mission to Mars. Launched 31 days apart on Atlas/Centaur rockets, the spacecraft arrived at their closest approach to Mars (3,430 kilometers, or 2,130 miles) just four days apart. They transmitted to Earth a total of 143 pictures of Mars as they approached the planet and 55 close-up pictures as they flew past the equator and southern hemisphere. The images, covering about 20% of the planet, revealed a surface quite different from Earth's moon, somewhat contrary to the impressions left by Mariner 4's images. Mariners 6 and 7 revealed cratered deserts, as well as depressions with no craters, huge concentrically terraced impact regions, and collapsed ridges. The spacecraft also studied the atmosphere and its chemical composition.
Mariner-H, also commonly known as Mariner 8, was (along with Mariner 9) part of the Mariner Mars 71 project. It was intended to go into Mars orbit and return images and data. Mariner 8 was launched on an Atlas-Centaur SLV-3C booster (AC-24). The main Centaur engine was ignited 265 seconds after launch, but the upper stage began to oscillate in pitch and tumbled out of control. The Centaur stage shut down 365 seconds after launch due to starvation caused by the tumbling. The Centaur and spacecraft payload separated and re-entered the Earth's atmosphere approximately 1500 km downrange and fell into the Atlantic Ocean about 560 km north of Puerto Rico.
Mariner 9 was the first spacecraft to orbit another planet. It carried an instrument payload similar to Mariners 6 and 7, but, because of the need for a larger propulsion system to control the spacecraft in Mars orbit, it weighed more than Mariners 6 and 7 combined. After 349 days in orbit, Mariner 9 had transmitted 7,329 images, covering over 80% of Mars' surface. The images revealed river beds, craters, massive extinct volcanoes, canyons including Valles Marineris, a massive system of canyons over 4,000 kilometers [about 2,500 miles] long. The vast chasm is named in honor of the spacecraft. Mariner 9 also found evidence of wind and water erosion and deposition, weather fronts, fogs, and more. Mars' tiny moons, Phobos and Deimos, were also photographed. The findings from the Mariner 9 missions laid the groundwork for the Viking program.
Mariner 10 was the seventh successful launch in the Mariner series, the first spacecraft to use the gravitational pull of one planet (Venus) to reach another (Mercury), and the first spacecraft mission to visit two planets. Mariner 10 was the first (and as of 2003 the only) spacecraft to visit Mercury. The spacecraft flew by Mercury three times in a retrograde heliocentric orbit and returned images and data on the planet. Mariner 10 returned the first-ever close-up images of Venus and Mercury. The primary scientific objectives of the mission were to measure Mercury's environment, atmosphere, surface, and body characteristics and to make similar investigations of Venus. Secondary objectives were to perform experiments in the interplanetary medium and to obtain experience with a dual-planet gravity-assist mission.
These missions are part of the Mars Exploration Program.