Information taken from Wikipedia and Books by Stephen and Lucy Hawking

The Pioneer program is a series of United States unmanned space missions that was designed for planetary exploration. There were a number of such missions in the program, but the most notable were Pioneer 10 and Pioneer 11, which explored the outer planets and left the solar system. Each carries a golden plaque, depicting a man and a woman and information about the origin and the creators of the probes, should any extraterrestrials find them someday.

The Pioneer plaque attached to Pioneers 10 and 11

Pioneer 10 (originally designated Pioneer F) is a 258-kilogram robotic space probe that completed the first mission to the planet Jupiter and became the first spacecraft to achieve escape velocity from the Solar System. The project was managed by the NASA Ames Research Center and the spacecraft was constructed by TRW Inc. Pioneer 10 was assembled around a hexagonal bus with a 2.74 m parabolic dish high-gain antenna oriented along the spin axis. Power was supplied by four radioisotope thermoelectric generators that provided a combined 155 W at the start of the mission.

Pioneer 10 was launched on March 2, 1972 by an Atlas-Centaur expendable vehicle from Cape Canaveral, Florida. Between July 15, 1972, and February 15, 1973, it became the first spacecraft to traverse the asteroid belt. Imaging of Jupiter began November 6, 1973, at a range of 25 million km, and a total of more than 500 images were transmitted. The closest approach to the planet was on December 4, 1973, at a range of 132,252 km. During the mission, the on-board instruments were used to study the asteroid belt, the environment around Jupiter, solar wind, cosmic rays, and eventually the far reaches of the solar system and heliosphere. Communication was lost on January 23, 2003, due to power constraints, with the probe at a distance of 12 billion kilometers (80 AU) from Earth.

Pioneer 10

Pioneer 11 (also known as Pioneer G) is a 259-kilogram (569 lb) robotic space probe launched by NASA on April 6, 1973 to study the asteroid belt, the environment around Jupiter and Saturn, solar wind, cosmic rays, and eventually the far reaches of the solar system and heliosphere. It was the first probe to encounter Saturn and the second to fly through the asteroid belt and by Jupiter. Due to power constraints and the vast distance to the probe, communication has been lost since November 30, 1995.

Vikings

The Viking program comprised a pair of American space probes sent to Mars, Viking 1 and Viking 2. Each spacecraft was composed of two main parts: an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.

It was the most expensive and ambitious mission ever sent to Mars, with a total cost of roughly US$1 billion. It was highly successful and formed most of the body of knowledge about Mars through the late 1990s and early 2000s.

The Viking program grew from NASA's earlier, and more ambitious, Voyager Mars program, which was not related to the successful Voyager deep space probes of the late 1970s. Viking 1 was launched on August 20, 1975, and the second craft, Viking 2, was launched on September 9, 1975, both riding atop Titan III-E rockets with Centaur upper stages. Viking 1 entered Mars orbit on June 19, 1976, with Viking 2 following suit on August 7.

Viking 1

The Mariner program was a program conducted by the American space agency NASA in conjunction with Jet Propulsion Laboratory (JPL) that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury from 1962 to 1973. The program included a number of firsts, including the first planetary flyby, the first pictures from another planet, the first planetary orbiter, and the first gravity assist maneuver.

Of the ten vehicles in the Mariner series, seven were successful and three were lost. The planned Mariner 11 and Mariner 12 vehicles evolved into Voyager 1 and Voyager 2 of the Voyager program, while the Viking 1 and Viking 2 Mars orbiters were enlarged versions of the Mariner 9 spacecraft. Other Mariner-based spacecraft, launched since Voyager, included the Magellan probe to Venus, and the Galileo probe to Jupiter. A second-generation Mariner spacecraft, called the Mariner Mark II series, eventually evolved into the Cassini–Huygens probe, now in orbit around Saturn.

Pathfinder and Sojourner

Mars Pathfinder (MESUR Pathfinder) was an American spacecraft that landed a base station with a roving probe on Mars in 1997. It consisted of a lander, renamed the Carl Sagan Memorial Station, and a lightweight (10.6 kg/23 lb) wheeled robotic Mars rover named Sojourner.

Launched on December 4, 1996 by NASA aboard a Delta II booster a month after the Mars Global Surveyor was launched, it landed on July 4, 1997 on Mars's Ares Vallis, in a region called Chryse Planitia in the Oxia Palus quadrangle. The lander then opened, exposing the rover which conducted many experiments on the Martian surface. The mission carried a series of scientific instruments to analyze the Martian atmosphere, climate, geology and the composition of its rocks and soil. It was the second project from NASA's Discovery Program, which promotes the use of low-cost spacecraft and frequent launches under the motto "cheaper, faster and better" promoted by the then administrator, Daniel Goldin. The mission was directed by the Jet Propulsion Laboratory (JPL), a division of the California Institute of Technology, responsible for NASA's Mars Exploration Program. The project manager was JPL's Tony Spear.

This mission was the first of a series of missions to Mars that included rovers, and was the first successful lander since the two Vikings landed on the red planet in 1976. Although the Soviet Union successfully sent rovers to the Moon as part of the Lunokhod program in the 1970s, its attempts to use rovers in its Mars probe program failed.

Curiosity is a car-sized robotic rover exploring Gale Crater on Mars as part of NASA's Mars Science Laboratory mission (MSL).

Curiosity was launched from Cape Canaveral on November 26, 2011, at 10:02 EST aboard the MSL spacecraft and successfully landed on Aeolis Palus in Gale Crater on Mars on August 6, 2012, 05:17 UTC. The Bradbury Landing site was less than 2.4 km (1.5 mi) from the center of the rover's touchdown target after a 563,000,000 km (350,000,000 mi) journey.

The rover's goals include: investigation of the Martian climate and geology; assessment of whether the selected field site inside Gale Crater has ever offered environmental conditions favorable for microbial life, including investigation of the role of water; and planetary habitability studies in preparation for future human exploration.

Curiosity's design will serve as the basis for a planned unnamed 2020 Mars rover mission. In December 2012, Curiosity's two-year mission was extended indefinitely.

As established by the Mars Exploration Program, the main scientific goals of the MSL mission are to help determine whether Mars could ever have supported life, as well as determining the role of water, and to study the climate and geology of Mars.The mission will also help prepare for human exploration. To contribute to these goals, MSL has eight main scientific objectives:

Biological

(1) Determine the nature and inventory of organic carbon compounds

(2) Investigate the chemical building blocks of life (carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur)

(3) Identify features that may represent the effects of biological processes (biosignatures)

Geological and geochemical

(4) Investigate the chemical, isotopic, and mineralogical composition of the Martian surface and near-surface geological materials

(5) Interpret the processes that have formed and modified rocks and soils

Planetary process

(6) Assess long-timescale (i.e., 4-billion-year) Martian atmospheric evolution processes

(7) Determine present state, distribution, and cycling of water and carbon dioxide

Surface radiation

(8) Characterize the broad spectrum of surface radiation, including galactic radiation, cosmic radiation, solar proton events and secondary neutrons

Curiosity

MESSENGER (an acronym of MErcury Surface, Space ENvironment, GEochemistry, and Ranging) (also the name of the roman god it is named after) is a robotic NASA spacecraft orbiting the planet Mercury, the first spacecraft ever to do so. The 485-kilogram (1,070 lb) spacecraft was launched aboard a Delta II rocket in August 2004 to study Mercury's chemical composition, geology, and magnetic field. It became the second mission after 1975's Mariner 10 (launched by NASA on November 3, 1973) to reach Mercury successfully when it made a flyby in January 2008, followed by a second flyby in October 2008, and a third flyby in September 2009.

The instruments carried by MESSENGER were tested on a complex series of flybys – the spacecraft flew by Earth once, Venus twice, and Mercury itself three times, allowing it to decelerate relative to Mercury using minimal fuel. MESSENGER successfully entered Mercury's orbit on March 18, 2011, and reactivated its science instruments on March 24, returning the first photo from Mercury orbit on March 29. MESSENGER's formal data collection mission began on April 4, 2011. On March 17, 2012, having collected close to 100,000 images, MESSENGER ended its one-year primary mission and entered an extended mission scheduled to last until March 2013.

During its stay in Mercury orbit, MESSENGER's instruments have yielded significant data, including a characterization of Mercury's magnetic field and the discovery of water ice at the planet's north pole.

Messenger Probe