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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.
Due to the complexity involved in engineering an interplanetary journey, the exploration of Mars has experienced a high failure rate, especially in the early attempts, with roughly two-thirds of all spacecraft destined for Mars failing before completing their missions, with some failing even before 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.
The NASA Mars Odyssey orbiter entered Mars orbit in 2001. Odyssey's Gamma Ray Spectrometer detected significant amounts of hydrogen in the upper metre or so of regolith on Mars. This hydrogen is thought to be contained in large deposits of water ice.
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 lifespan.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.
|2013||Nov 2013 – Jan 2014|
|2016||Jan 2016 – Apr 2016|
|2018||Apr 2018 – May 2018|
|2020||Jul 2020 – Sep 2020|
The minimum-energy launch windows for a Martian expedition occur at intervals of approximately two years and two months, i.e. 780 days (the planet's synodic period with respect to Earth). In addition, the lowest available transfer energy varies on a roughly 16-year cycle. For example, there was a minimum in the 1969 and 1971 launch windows, rising to a peak in the late 1970s, and hitting another low in 1986 and 1988.
In addition to these minimum-energy trajectories, which occur when the planets are aligned so that the Earth to Mars transfer trajectory goes halfway around the Sun, an alternate trajectory that has been proposed goes first inward toward Venus orbit, and then outward, resulting in a longer trajectory that goes about 360 degrees around the Sun.
The following entails a brief overview of Mars exploration, oriented towards orbiters and flybys; see also Mars landing.
The Mars 1M program (sometimes dubbed Marsnik in Western media) was the first Soviet unmanned spacecraft interplanetary exploration program, which consisted of two flyby probes launched towards Mars in October 1960, Mars 1960A and Mars 1960B (also known as Korabl 4 and Korabl 5 respectively). After launch, the third stage pumps on both launchers were unable to develop enough thrust to commence ignition, so Earth parking orbit was not achieved. The spacecraft reached an altitude of 120 km before reentry.
Mars 1962A was a Mars fly-by mission, launched on October 24, 1962 and Mars 1962B a lander mission, launched in late December of the same year. Both failed from either breaking up as they were going into Earth orbit or having the upper stage explode in orbit during the burn to put the spacecraft into trans-Mars trajectory.
Mars 1 (1962 Beta Nu 1), an automatic interplanetary spacecraft launched to Mars on November 1, 1962, was the first probe of the Soviet Mars probe program. Mars 1 was intended to fly by the planet at a distance of about 11,000 km and take images of the surface as well as send back data on cosmic radiation, micrometeoroid impacts and Mars' magnetic field, radiation environment, atmospheric structure, and possible organic compounds. Sixty-one radio transmissions were held, initially at two day intervals and later at 5 day intervals, from which a large amount of interplanetary data was collected. On 21 March 1963, when the spacecraft was at a distance of 106,760,000 km from Earth, on its way to Mars, communications ceased due to failure of its antenna orientation system.
In 1964, both Soviet probe launches, of Zond 1964A on June 4, and Zond 2 on November 30, (part of the Zond program), resulted in failures. Zond 1964A had a failure at launch, while communication was lost with Zond 2 en route to Mars after a mid-course maneuver, in early May 1965.
In 1969, and as part of the Mars probe program, the Soviet Union prepared two identical 5-ton orbiters called M-69, dubbed by NASA as Mars 1969A and Mars 1969B. Both probes were lost in launch-related complications with the newly developed Proton rocket.
The USSR intended to have the first artificial satellite of Mars beating the planned American Mariner 8 and Mariner 9 Martian orbiters. In May 1971, one day after Mariner 8 malfunctioned at launch and failed to reach orbit, Cosmos 419 (Mars 1971C), a heavy probe of the Soviet Mars program M-71, also failed to launch. This spacecraft was designed as an orbiter only, while the next two probes of project M-71, Mars 2 and Mars 3, were multipurpose combinations of an orbiter and a lander. They were successfully launched in mid-May 1971 and reached Mars about seven months later. On November 27, 1971 the lander of Mars 2, while having crash-landed due to an on-board computer malfunction became the first man-made object to touch down on Mars. In December 2, 1971 Mars 3 lander became the first spacecraft to attain a soft landing, but its transmission was interrupted after 14.5 seconds and no useful scientific data was returned to Earth.
The Mars 2 and 3 orbiters sent back a relatively 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 magnetic fields.
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.
In 1964, NASA's Jet Propulsion Laboratory made two attempts at reaching Mars. Mariner 3 and Mariner 4 were identical spacecraft designed to carry out the first flybys of Mars. Mariner 3 was launched on November 5, 1964, but the shroud encasing the spacecraft atop its rocket failed to open properly, dooming the mission. Three weeks later, on November 28, 1964, Mariner 4 was launched successfully on a 7½-month voyage to the red planet.
Mariner 4 flew past Mars on July 14, 1965, providing the first close-up photographs of another planet. The pictures, gradually played back to Earth from a small tape recorder on the probe, showed impact craters. It provided radically more accurate data about the planet; a surface atmospheric pressure of about 1% of Earth's and daytime temperatures of −100 °C (−148 °F) were estimated. No magnetic field or Martian radiation belts were detected. The new data meant redesigns for then planned Martian landers, and showed life would have a more difficult time surviving there than previously anticipated.
NASA continued the Mariner program with another pair of Mars flyby probes, Mariner 6 and 7. They were sent at the next launch window, and reached the planet in 1969. During the following launch window the Mariner program again suffered the loss of one of a pair of probes. Mariner 9 successfully entered orbit about Mars, the first spacecraft ever to do so, after the launch time failure of its sister ship, Mariner 8. When Mariner 9 reached Mars, it and two Soviet orbiters (Mars 2 and Mars 3, see Mars probe program below) found that a planet-wide dust storm was in progress. The mission controllers used the time spent waiting for the storm to clear to have the probe rendezvous with, and photograph, Phobos. When the storm cleared sufficiently for Mars' surface to be photographed by Mariner 9, the pictures returned represented a substantial advance over previous missions. These pictures were the first to offer more detailed evidence that liquid water might at one time have flowed on the planetary surface. They also finally discerned the true nature of many Martian albedo features. For example, Nix Olympica was one of only a few features that could be seen during the planetary duststorm, revealing it to be the highest mountain (volcano, to be exact) on any planet in the entire Solar System, and leading to its reclassification as Olympus Mons.
The Viking program launched Viking 1 and 2 spacecraft to Mars in 1975; The program consisted of two orbiters and two landers – these were the first two spacecraft to successfully land on Mars.
The primary scientific objectives of the lander mission were to search for biosignatures and observe meteorologic, seismic and magnetic properties of Mars. The results of the biological experiments on board the Viking landers remain inconclusive, with a re-analysis of the Viking data published in 2012 suggesting signs of microbial life on Mars.
The Viking orbiters revealed that large floods of water carved deep valleys, eroded grooves into bedrock, and traveled thousands of kilometers. Areas of branched streams, in the southern hemisphere, suggest that rain once fell.
Mars Pathfinder was a U.S. spacecraft that landed a base station with a roving probe on Mars in July 4, 1997. It consisted of a lander and a small 10.6 kilograms (23 lb) wheeled robotic rover named Sojourner, which was the first rover to operate on the surface of Mars. In addition to scientific objectives, the Mars Pathfinder mission was also a "proof-of-concept" for various technologies, such as airbag landing system and automated obstacle avoidance, both later exploited by the Mars Exploration Rovers.
After the 1992 failure of NASA's Mars Observer orbiter, NASA retooled and launched Mars Global Surveyor (MGS). This mission was the first successful United States mission, and the first fully successful mission overall, to the red planet in two decades when it launched November 7, 1996, and entered orbit on September 12, 1997. After a year and a half trimming its orbit from a looping ellipse to a circular track around the planet, the spacecraft began its primary mapping mission in March 1999. It observed the planet from a low-altitude, nearly polar orbit over the course of one complete Martian year, the equivalent of nearly two Earth years. Mars Global Surveyor completed its primary mission on January 31, 2001, and completed several extended mission phases.
The mission studied the entire Martian surface, atmosphere, and interior, and returned more data about the red planet than all previous Mars missions combined. The data has been archived and remains available publicly.
Among key scientific findings, Global Surveyor took pictures of gullies and debris flow features that suggest there may be current sources of liquid water, similar to an aquifer, at or near the surface of the planet. Similar channels on Earth are formed by flowing water, but on Mars the temperature is normally too cold and the atmosphere too thin to sustain liquid water. Nevertheless, many scientists hypothesize that liquid groundwater can sometimes surface on Mars, erode gullies and channels, and pool at the bottom before freezing and evaporating.
Magnetometer readings showed that the planet's magnetic field is not globally generated in the planet's core, but is localized in particular areas of the crust. New temperature data and closeup images of the Martian moon Phobos showed that its surface is composed of powdery material at least 1 metre (3 feet) thick, caused by millions of years of meteoroid impacts. Data from the spacecraft's laser altimeter gave scientists their first 3-D views of Mars' north polar ice cap.
In 2001 NASA's Mars Odyssey orbiter arrived at Mars. Its mission is to use spectrometers and imagers to hunt for evidence of past or present water and volcanic activity on Mars. In 2002, it was announced that the probe's gamma ray spectrometer and neutron spectrometer had detected large amounts of hydrogen, indicating that there are vast deposits of water ice in the upper three meters of Mars' soil within 60° latitude of the south pole.
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 analyze soil beneath the dusty surface.
The orbiter entered Mars orbit on December 25, 2003, and Beagle 2 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. The Mars Express Orbiter confirmed the presence of water ice and carbon dioxide ice at the planet's south pole, while NASA had previously confirmed their presence at the north pole of Mars.
|This section requires expansion. (August 2012)|
See Mars landing for more on the landers.
Mars Reconnaissance Orbiter is a multipurpose spacecraft designed to conduct reconnaissance and exploration of Mars from orbit. The $720 million USD spacecraft was built by Lockheed Martin under the supervision of the Jet Propulsion Laboratory, launched August 12, 2005, and attained Martian orbit on March 10, 2006.
The MRO contains a host of scientific instruments such as the HiRISE camera, CTX camera, CRISM, and SHARAD. The HiRISE camera is used to analyze Martian landforms, whereas CRISM and SHARAD can detect water, ice, and minerals on and below the surface. Additionally, MRO is paving the way for upcoming generations of spacecraft through daily monitoring of Martian weather and surface conditions, searching for future landing sites, and testing a new telecommunications system that enable it to send and receive information at an unprecedented bitrate, compared to previous Mars spacecraft. Data transfer to and from the spacecraft occurs faster than all previous interplanetary missions combined and allows it to serve as an important relay satellite for other missions.
The ESA Rosetta space probe mission to the comet 67P/Churyumov-Gerasimenko flew within 250 km of Mars on February 25, 2007 in a gravitational slingshot designed to slow and redirect the spacecraft. The NASA Dawn spacecraft also used the gravity of Mars to change direction and velocity, and did a little science in conjunction with the many probes already there. Dawn passed the red planet in February 2009.
In 8 November 2011, Russia's Roscosmos launched an ambitious mission called Fobos-Grunt. It was a lander aimed to retrieve a sample back to Earth from Mars' moon Phobos, and place the Chinese Yinghuo-1 probe in Mars' orbit. The Fobos-Grunt mission suffered a complete control and communications failure during launch and was left stranded in low Earth orbit, later falling back to Earth. The Yinghuo-1 satellite and Fobos-Grunt underwent destructive re-entry on 15 January 2012, finally disintegrating over the Pacific Ocean.
The NASA Mars Science Laboratory mission with its rover named Curiosity, was launched on November 26, 2011. The rover carries instruments designed to look for past or present conditions relevant to the past or present habitability of Mars. The Curiosity rover landed on Mars on Aeolis Palus in Gale Crater, near Aeolis Mons (formerly, "Mount Sharp"), on August 6, 2012 at 05:14:39 UTC.
Future mission ideas include new polar probes, Martian aircraft, or a network of small stations. Longterm areas of study may include Martian lava tubes, resource utilization, and electronic charge carriers in rocks. Micromissions are another possibility, such as piggybacking a small spacecraft on an Ariane 5 rocket and using a lunar gravity assist to get to Mars.
Starting in 1960 the Soviets launched a series of probes to Mars. The first successful fly-by of Mars was on July 14–15, 1965, by NASA's Mariner 4. On November 14, 1971 Mariner 9 became the first space probe to orbit another planet when it entered into orbit around Mars. The amount of data returned by probes increased dramatically as technology improved.
The first to contact the surface were two Soviet probes: Mars 2 lander on November 27 and Mars 3 lander on December 2, 1971—Mars 2 failed during descent and Mars 3 about twenty seconds after landing. Mars 6 failed during descent but did return some corrupted atmospheric data in 1974.  The 1975 NASA launches of the Viking program consisted of two orbiters, each with a lander that successfully touched down in 1976. Viking 1 remained operational for six years, Viking 2 for three. The Viking landers relayed the first color panoramas of Mars and the Viking orbiters mapped the surface so well that the images remain in use.
The Soviet probes Phobos 1 and 2 were sent to Mars in 1988 to study Mars and its two moons, with a focus on Phobos. Phobos 1 lost contact on the way to Mars. Phobos 2, while successfully photographing Mars and Phobos, failed before it was set to release two landers to the surface of Phobos.
Roughly two-thirds of all spacecraft destined for Mars have failed without completing their missions, and it has a reputation as difficult space exploration target. Missions that ended prematurely after Phobos 1 & 2 (1988) include Mars Observer (Launched in 1990), Mars 96 (1996), Mars Climate Orbiter (1999), Mars Polar Lander with Deep Space 2 (1999), Nozomi (2003), Beagle 2 (2003), and Fobos-Grunt with Yinghuo-1 (2011). (See Probing difficulties section)
Following the 1992 failure of the Mars Observer orbiter, the NASA Mars Global Surveyor achieved Mars orbit in 1997. This mission was a complete success, having finished its primary mapping mission in early 2001. Contact was lost with the probe in November 2006 during its third extended program, spending exactly 10 operational years in space. The NASA Mars Pathfinder, carrying a robotic exploration vehicle Sojourner, landed in the Ares Vallis on Mars in the summer of 1997, returning many images.
Phoenix landed on the north polar region of Mars on May 25, 2008. Its robotic arm dug into the Martian soil and the presence of water ice was confirmed on June 20, 2008. The mission concluded on November 10, 2008 after contact was lost. In 2008, the price of transporting material from the surface of Earth to the surface of Mars was approximately US$309,000 per kilogram.
Many people have long advocated a manned mission to Mars as the next logical step for a manned space program after lunar exploration. Aside from the prestige such a mission would bring, advocates argue that humans would easily be able to outperform robotic explorers, justifying the expense. Aerospace engineer Bob Zubrin is one of the proponents of such missions. Some critics contend unmanned robots can perform better than humans at a fraction of the expense. If life exists on Mars, a manned mission could contaminate it by introducing earthly microbes, so robotic exploration would be preferable. A list of hypothetical or proposed manned Mars missions is located at manned mission to Mars. See also, colonization of Mars.
The ESA has plans to land humans on Mars between 2030 and 2035. This will be preceded by successively larger probes, starting with the launch of the ExoMars probe and a planned joint NASA–ESA Mars sample return mission.
Manned exploration by the United States was identified as a long-term goal in the Vision for Space Exploration announced in 2004 by then US President George W. Bush. The planned Orion spacecraft would be used to send a human expedition to Earth's moon by 2020 as a stepping stone to a Mars expedition. On September 28, 2007, NASA administrator Michael D. Griffin stated that NASA aims to put a man on Mars by 2037.
Mars Direct, a low-cost human mission proposed by Robert Zubrin, founder of the Mars Society, would use heavy-lift Saturn V class rockets, such as the SpaceX Falcon X, or, the Ares V, to skip orbital construction, LEO rendezvous, and lunar fuel depots. A modified proposal, called "Mars to Stay", involves not returning the first immigrant explorers immediately, if ever (see Colonization of Mars). Refs:   
The challenge, complexity and length of Mars missions make it likely that failures can occur. The high failure rate of missions launched from Earth attempting to explore Mars was informally called the "Mars Curse" or "Martian Curse". The phrase "Galactic Ghoul" or "Great Galactic Ghoul", referring to a fictitious space monster that subsists on a diet of Mars probes, was coined in 1997 by Time Magazine journalist Donald Neff, and is sometimes facetiously used to "explain" the recurring difficulties.
Two Soviet probes were sent to Mars in 1988 as part of the Phobos program. Phobos 1 operated nominally until an expected communications session on 2 September 1988 failed to occur. The problem was traced to a software error, which deactivated attitude thrusters causing the spacecrafts' solar arrays to no longer point at the Sun, depleting Phobos 1 batteries. Phobos 2 operated nominally throughout its cruise and Mars orbital insertion phases on January 29, 1989, gathering data on the Sun, interplanetary medium, Mars, and Phobos. Shortly before the final phase of the mission, during which the spacecraft was to approach within 50 m of Phobos' surface and release two landers, one a mobile 'hopper', the other a stationary platform, contact with Phobos 2 was lost. The mission ended when the spacecraft signal failed to be successfully reacquired on March 27, 1989. The cause of the failure was determined to be a malfunction of the on-board computer.
Just a few years later Mars Observer failed as it approached Mars. 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 fatal errors. Mars Climate Orbiter was noted for mixing up English units with metric units, causing the orbiter to burn up while entering Mars' atmosphere.
|It has been suggested that Mars#Timeline be merged into this article or section. (Discuss) Proposed since January 2012.|
Source: international Mars mission log
|Mission type||Success rate||Total attempts||Success||Partial success||Launch failure||Failed en route||Failed to orbit/land|
|Sample return||0%||1||1 (Phobos)|
|Mission (1960–1969)||Launch||Arrival at Mars||Termination||Elements||Result|
|Mars 1M No.1||10 October 1960||10 October 1960||Flyby||Launch failure|
|Mars 1M No.2||14 October 1960||14 October 1960||Flyby||Launch failure|
|Mars 2MV-4 No.1||24 October 1962||24 October 1962||Flyby||Broke up shortly after launch|
|Mars 1||1 November 1962||21 March 1963||Flyby||Some data collected, but lost contact before reaching Mars, flyby at approx. 193,000 km|
|Mars 2MV-3 No.1||4 November 1962||19 January 1963||Lander||Failed to leave Earth's orbit|
|Mariner 3||5 November 1964||5 November 1964||Flyby||Failure during launch ruined trajectory|
|Mariner 4||28 November 1964||14 July 1965||21 December 1967||Flyby||Success (21 images returned)|
|Zond 2||30 November 1964||May 1965||Flyby||Communication lost three months before reaching Mars|
|Mariner 6||25 February 1969||31 July 1969||August 1969||Flyby||Success|
|Mariner 7||27 March 1969||5 August 1969||August 1969||Flyby||Success|
|Mars 2M No.521||27 March 1969||27 March 1969||Orbiter||Launch failure|
|Mars 2M No.522||2 April 1969||2 April 1969||Orbiter||Launch failure|
|Mission (1970–1989)||Launch||Arrival at Mars||Termination||Elements||Result|
|Mariner 8||8 May 1971||8 May 1971||Orbiter||Launch failure|
|Kosmos 419||10 May 1971||12 May 1971||Orbiter||Launch failure|
|Mariner 9||30 May 1971||13 November 1971||27 October 1972||Orbiter||Success (first successful orbit)|
|Mars 2||19 May 1971||27 November 1971||22 August 1972||Orbiter||Success|
|27 November 1971||Lander, rover||Crashed on surface of Mars|
|Mars 3||28 May 1971||2 December 1971||22 August 1972||Orbiter||Success|
|2 December 1971||Lander, rover||Partial success. First successful landing; landed softly but ceased transmission within 15 seconds|
|Mars 4||21 July 1973||10 February 1974||10 February 1974||Orbiter||Could not enter orbit, made a close flyby|
|Mars 5||25 July 1973||2 February 1974||21 February 1974||Orbiter||Partial success. Entered orbit and returned data, but failed within 9 days|
|Mars 6||5 August 1973||12 March 1974||12 March 1974||Lander||Partial success. Data returned during descent but not after landing on Mars|
|Mars 7||9 August 1973||9 March 1974||9 March 1974||Lander||Landing probe separated prematurely; entered heliocentric orbit|
|Viking 1||20 August 1975||20 July 1976||17 August 1980||Orbiter||Success|
|13 November 1982||Lander||Success|
|Viking 2||9 September 1975||3 September 1976||25 July 1978||Orbiter||Success|
|11 April 1980||Lander||Success|
|Phobos 1||7 July 1988||2 September 1988||Orbiter||Contact lost while en route to Mars|
|Phobos 2||12 July 1988||29 January 1989||27 March 1989||Orbiter||Partial success: entered orbit and returned some data. Contact lost just before deployment of landers|
|Mission (1990–1999)||Launch||Arrival at Mars||Termination||Elements||Result|
|Mars Observer||25 September 1992||24 August 1993||21 August 1993||Orbiter||Lost contact just before arrival|
|Mars Global Surveyor||7 November 1996||11 September 1997||5 November 2006||Orbiter||Success|
|Mars 96||16 November 1996||17 November 1996||Orbiter, lander, penetrator||Launch failure|
|Mars Pathfinder||4 December 1996||4 July 1997||27 September 1997||Lander, rover||Success|
|Nozomi (Planet-B)||3 July 1998||9 December 2003||Orbiter||Complications while en route; Never entered orbit|
|Mars Climate Orbiter||11 December 1998||23 September 1999||23 September 1999||Orbiter||Crashed on surface due to metric-imperial mix-up|
|Mars Polar Lander||3 January 1999||3 December 1999||3 December 1999||Lander||Crash-landed on surface due to improper hardware testing|
|Deep Space 2 (DS2)||Hard landers|
|Mission (2000–2009)||Launch||Arrival at Mars||Termination||Elements||Result|
|2001 Mars Odyssey||7 April 2001||24 October 2001||Currently operational||Orbiter||Success|
|Mars Express||2 June 2003||25 December 2003||Currently operational||Orbiter||Success|
|Beagle 2||6 February 2004||Lander||Landing failure; fate unknown.|
|MER-A Spirit||10 June 2003||4 January 2004||22 March 2011||Rover||Success|
|MER-B Opportunity||7 July 2003||25 January 2004||Currently operational||Rover||Success|
|Rosetta||2 March 2004||25 February 2007||Currently operational||Gravity assist enroute to comet 67P/Churyumov-Gerasimenko||Success|
|Mars Reconnaissance Orbiter||12 August 2005||10 March 2006||Currently operational||Orbiter||Success|
|Phoenix||4 August 2007||25 May 2008||10 November 2008||Lander||Success|
|Dawn||27 September 2007||17 February 2009||Currently operational||Gravity assist to Vesta||Success|
|Mission (2010–2019)||Launch||Arrival at Mars||Termination||Elements||Result|
|Fobos-Grunt||8 November 2011||8 November 2011||Phobos lander, sample return||Failed to leave Earth orbit. Fell back to Earth.|
|Yinghuo-1||8 November 2011||Orbiter|
|MSL Curiosity||26 November 2011||6 August 2012||Currently operational||Rover||Success|
|Name|| Estimated |
|Mangalyaan||20 November 2013||Orbiter||Research on Mars atmosphere|
|MAVEN||2013||Orbiter||Explore Mars' climate history.|
|InSight||2016||Lander, drill||Study interior structure of Mars.|
|2016||Orbiter, lander||Trace Gas Orbiter to deliver a lander.|
|2018||Lander, rover||Russian lander to deploy ExoMars rover|
|MetNet precursor||2014 or later||Impact lander||Precursor for Multi-lander network.|
|Name|| Estimated |
|Mars One Supply Vehicle||2016||Lander||The first supply vehicle is proposed for launch in 2016.|
|Mars Geyser Hopper||2016||Lander||Will have the ability to fly or "hop" at least twice from its landed location to reposition itself close to a CO2 geyser site.|
|MetNet||after precursor||Multi-lander network||Simultaneous meteorological measurements at multiple locations.|
|Red Dragon||2018||Lander||Falcon Heavy rocket with a Dragon capsule; would look for biosignatures.|
|Network||2022||3 landers||Meteorological network concept|
|Phootprint||2022||Lander and ascent stage||Mars Moon Sample Return Mission|
|Mars One||2022||Manned mission||Colony|
|MELOS-1||2020s||Orbiter, lander||Would study geology and atmosphere.|
|Mars-Grunt||2020s||Orbiter, lander, ascent stage||Single launch Mars sample return|
|BOLD||–||6 landers||The Biological Oxidant and Life Detection would perform astrobiology tests on sub-surface soil|
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