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In 1969, the Soviet Union prepared a 5-ton orbiter called M-69. Two copies of the probe, Mars 1969A and Mars 1969B, were lost in launch related complications caused by problems with the newly developed Proton rockets.In 1971, shortly after the Cosmos 419 (Mars 1971C), that intended to be a first Martian orbiter, was lost in the fourth stage of the launch due to issues concerning the failure in the separation of Cosmos' payload from the launch vehicle, the Soviet Union successfully sent probes Mars 2 and Mars 3, as part of the Mars probe program M-71.

The Mars 2 and 3 orbiters sent back a large volume of data covering the period from December 1971 to March 1972, although transmissions continued through to August. By 22 August 1972, after sending back data and a total of 60 pictures, Mars 2 and 3 concluded their missions. The images and data enabled creation of surface relief maps, and gave information on the Martian gravity and magnetosphere.

In 1973, the Soviet Union sent four more probes to Mars: the Mars 4 and Mars 5 orbiters and the Mars 6 and Mars 7 fly-by/lander combinations. All missions except Mars 7 sent back data, with Mars 5 being most successful. Mars 5 transmitted 60 images before a loss of pressurization in the transmitter housing, ended the mission. Mars 6 lander transmitted data during descent, but failed upon impact. Mars 4 flew by the planet at a range of 2200 km returning one swath of pictures and radio occultation data, which constituted the first detection of the nightside ionosphere on Mars. Mars 7 probe separated prematurely from the carrying vehicle due to a problem in the operation of one of the onboard systems (altitude control or retro-rockets) and missed the planet by 1300 km.Years earlier, in 1970 Soviet Union began the design of Mars 4NM and Mars 5NM missions with superheavy unmanned Martian spacecrafts. First was Marsokhod with planned date of start in 1973 and second was Mars sample return mission planned to 1975. Both spacecrafts intended to launch on N1 superrocket. But this rocket never flew successfully and Mars 4NM and Mars 5NM projects were cancelled

In 1976 the two American Viking probes entered orbit about Mars and each released a lander module that made a successful soft landing on the planet's surface. The two missions returned the first color pictures and extensive scientific information. Measured temperatures at the landing sites ranged from 150 to 250 K, with a variation over a given day of 35 to 50 K. Seasonal dust storms, pressure changes, and movement of atmospheric gases between the polar caps were observed. A biology experiment produced possible evidence of life, but it was not corroborated by other on-board experiments.While searching for a suitable landing spot for Viking 2's lander, the Viking 1 orbiter photographed the landform that constitutes the so-called "Face on Mars" on July 25, 1976.The Viking program was a descendant of the cancelled Voyager program, whose name was later reused for a pair of outer solar system probes.

The Mars Pathfinder spacecraft, launched one month after Global Surveyor, landed on July 4, 1997. Its landing site was an ancient flood plain in Mars' northern hemisphere called Ares Vallis, which is among the rockiest parts of Mars. It carried a tiny remote-controlled rover called Sojourner, which traveled a few meters around the landing site, exploring the conditions and sampling rocks around it. Newspapers around the world carried images of the lander dispatching the rover to explore the surface of Mars in a way never achieved before.

Until the final data transmission on September 27, 1997, Mars Pathfinder returned 16,500 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors. Findings from the investigations carried out by scientific instruments on both the lander and the rover suggest that Mars was at one time in its past warm and wet, with water existing in its liquid state and a thicker atmosphere. The mission website was the most heavily-trafficked up to that time.

Mars 96, an orbiter launched on November 16, 1996 by Russia failed, when the planned second burn of the Block D-2 fourth stage did not occur. Following the success of Global Surveyor and Pathfinder, another spate of failures occurred in 1998 and 1999, with the Japanese Nozomi orbiter and NASA's Mars Climate Orbiter, Mars Polar Lander, and Deep Space 2 penetrators all suffering various terminal errors. Mars Climate Orbiter is infamous for Lockheed Martin engineers mixing up the usage of English units with metric units, causing the orbiter to burn up while entering Mars' atmosphere. Beagle 2

On June 2, 2003, the European Space Agency's Mars Express set off from Baikonur Cosmodrome to Mars. The Mars Express craft consists of the Mars Express Orbiter and the lander Beagle 2. Although the landing probe was not designed to move, it carried a digging device and the smallest mass spectrometer created to date, as well as a range of other devices, on a robotic arm in order to accurately analyse soil beneath the dusty surface.

The orbiter entered Mars orbit on December 25, 2003, and Beagle 2 should have entered Mars' atmosphere the same day. However, attempts to contact the lander failed. Communications attempts continued throughout January, but Beagle 2 was declared lost in mid-February, and a joint inquiry was launched by the UK and ESA that blamed Colin Pillinger's poor project management. Nevertheless, Mars Express Orbiter confirmed the presence of water ice and carbon dioxide ice at the planet's south pole. NASA had previously confirmed their presence at the north pole of Mars.

Shortly after the launch of Mars Express, NASA sent a pair of twin rovers toward the planet as part of the Mars Exploration Rover Mission. On 10 June 2003, NASA's MER-A (Spirit) Mars Exploration Rover was launched. It successfully landed in Gusev Crater (believed once to have been a crater lake) on 3 January 2004. It examined rock and soil for evidence of the area's history of water. On July 7, 2003, a second rover, MER-B (Opportunity) was launched. It landed on 24 January 2004 in Meridiani Planum (where there are large deposits of hematite, indicating the presence of past water) to carry out similar geological work.

Despite a temporary loss of communication with the Spirit Rover (caused by a filesystem anomaly delaying exploration for several days, both rovers eventually began exploring their landing sites. The rover Opportunity landed in a particularly interesting spot, a crater with bedrock outcroppings.

In fast succession mission team members announced on 2 March that data returned from the rover showed that these rocks were once "drenched in water", and on 23 March that it was concluded that they were laid down underwater in a salty sea. This represented the first strong direct evidence for liquid water being on Mars at some time in the past.

Having only been designed for three month missions, they both lasted much longer than planned, and Spirit lost contact with Earth in March 2010. Opportunity, however, continues to carry out surveys of the planet, and surpassed 50 miles on its odometer earlier this year. These rovers have discovered new things, including Heat Shield Rock, the first meteorite to be discovered on another planet.

Phoenix launched on August 4, 2007, and touched down on the northern polar region of Mars on May 25, 2008. It is famous for having been successfully photographed while landing, since this was the first time one spacecraft captured the landing of another spacecraft onto a planetary body (the Moon not being a planet, but a satellite).
Phoenix was followed by the Mars Science Laboratory, a rover more capable than Spirit and Opportunity. Originally the Mars Science Laboratory was intended for a launch during 2009 however, it was launched on November 26, 2011.Russia launched Fobos-Grunt, a sample return mission to Phobos, along with the joint Chinese Yinghuo-1 Mars orbiter in November 2011, which went into Earth orbit successfully, but failed to launch to Mars.

The ESA ExoMars rover mission is tentatively planned for 2018. ExoMars should obtain soil samples from up to 2 meters depth and make an extensive search for organic and biochemical substances. Other possible future missions are the Discovery program's Mars Geyser Hopper and InSight, a lander for studying the deep interior of Mars. Future missions are sometimes included in Planetary Science Decadal Surveys.There are proposals for Mars Sample Return Missions, but this has been delayed until at least 2024. This mission, a collaboration between ESA and NASA, is part of the Aurora Programme.

The exploration of Mars has taken place over hundreds of years, beginning in earnest with the invention and development of the telescope since the 1600s. Increasingly detailed views of the planet from Earth inspired speculation about its environment and possible life – even intelligent civilizations – that might be found there. Probes sent from Earth beginning in the late 20th century have yielded a dramatic increase in knowledge about the Martian system, focused primarily on understanding its geology and possible habitability potential.

Engineering interplanetary journeys is very complicated, so the exploration of Mars has experienced a high failure rate, especially in earlier attempts. Roughly two-thirds of all spacecraft destined for Mars failed before completing their missions, and there are some that failed before their observations could begin. However, missions have also met with unexpected levels of success, such as the twin Mars Exploration Rovers operating for years beyond their original mission specifications.

Since 6 August 2012, there have been two rovers on the surface of Mars beaming signals back to Earth (Opportunity, and Curiosity of the Mars Science Laboratory mission), and three orbiters currently surveying the planet: Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter.To date, no sample return missions have been attempted for Mars, and one attempted return mission for Mars' moon Phobos (Fobos-Grunt) has failed.

The Mars Express mission of the European Space Agency (ESA) reached Mars in 2003. It carried the Beagle 2 lander, which was not heard from after being released and was declared lost in February 2004.In early 2004 the Mars Express Planetary Fourier Spectrometer team announced the orbiter had detected methane in the Martian atmosphere. ESA announced in June 2006 the discovery of aurorae on Mars.

In January 2004, the NASA twin Mars Exploration Rovers named Spirit (MER-A) and Opportunity (MER-B) landed on the surface of Mars. Both have met or exceeded all their targets. Among the most significant scientific returns has been conclusive evidence that liquid water existed at some time in the past at both landing sites. Martian dust devils and windstorms have occasionally cleaned both rovers' solar panels, and thus increased their lifespa  Spirit Rover (MER-A) was active until 2010, when it stopped sending data.

On March 10, 2006, the NASA Mars Reconnaissance Orbiter (MRO) probe arrived in orbit to conduct a two-year science survey. The orbiter began mapping the Martian terrain and weather to find suitable landing sites for upcoming lander missions. The MRO snapped the first image of a series of active avalanches near the planet's north pole, scientists said March 3, 2008.

The Mars Science Laboratory mission was launched on November 26, 2011 and it delivered the Curiosity rover, on the surface of Mars on August 6, 2012 UTC. It is larger and more advanced than the Mars Exploration Rovers, with a velocity of up to 90 meters per hour (295 feet per hour).Experiments include a laser chemical sampler that can deduce the make-up of rocks at a distance of 7 meters

Mars has long been the subject of human fascination. Early telescopic observations revealed color changes on the surface that were originally attributed to seasonal vegetation as well as apparent linear features that were ascribed to intelligent design. These early and erroneous interpretations led to widespread public interest in Mars. Further telescopic observations found Mars' two moons, Phobos and Deimos, the polar ice caps, and the feature now known as Olympus Mons, the solar system's tallest mountain. These discoveries piqued further interest in the study and exploration of the red planet. Mars is a rocky planet, like Earth, that formed around the same time, yet with only half the diameter of Earth, and a far thinner atmosphere, it has a cold and desert-like surface. It is notable, however, that although the planet has only one quarter of the surface area of the Earth, it has about the same land area, since only one quarter of the surface area of the Earth is land.