Dozens of missions have launched to Mars to better understand this close neighbor to Earth. Some were flybys, gathering information only in brief bursts. Others were long-standing orbiters that lasted years at the Red Planet. And perhaps most challenging of all were landers — some stationary, and some roving for miles across the surface.
Since the first successful flyby in 1965, four entities have successfully made it to Mars: NASA, the Soviet Union, the European Space Agency and the Indian Space Research Organization, while others, including Japan and China, have tried. Below is a brief history of missions to the Red Planet.
1960s-early 1970s: Flybys & photographs
The first attempts to reach Mars happened near the dawn of space exploration. Considering that the first satellite, Sputnik, launched in 1957, it is extraordinary that only three years later the Soviet Union looked to extend its work to Mars. The nation made multiple attempts to reach the Red Planet, and NASA also tried with its spacecraft Mariner 3:
- Marsnik 1 (USSR) launched Oct. 10, 1960, on an intended Mars flyby. The spacecraft did not reach Earth orbit.
- Marsnik 2 (USSR) launched Oct. 14, 1960, on an intended Mars flyby. The spacecraft did not reach Earth orbit.
- Sputnik 22 (USSR) launched Oct. 24, 1962, on an intended Mars flyby. The spacecraft achieved Earth orbit only.
- Mars 1 (USSR) launched Nov. 1, 1962, on an intended Mars flyby. The spacecraft's radio failed at 65.9 million miles (106 million kilometers).
- Sputnik 24 (USSR) launched Nov. 4, 1962, on an intended Mars flyby. The spacecraft achieved Earth orbit only.
- Mariner 3 (U.S.) launched Nov. 5, 1964, on an intended Mars flyby. The shroud encasing the spacecraft at the top of the rocket failed to jettison.
The first success: While these missions didn't reach their target, Mariner 4 did. The U.S. spacecraft, which launched on Nov. 28, 1953, was the first to fly by Mars on July 14, 1965, and sent 21 photos back to Earth. Two days after Mariner 4 launched, the Soviet Union tried again with Zond 2. The spacecraft passed Mars but its radio failed and it did not return any planetary data.
NASA also sent Mariners 6 and 7 in 1969, which reached Mars and sent back a few dozen photos. Coincidentally, all of these spacecraft flew over areas of Mars that were cratered. This gave a false first impression that Mars looked like the moon.
Several more attempts were made between 1969 and 1971. Most failed to reach their target:
- Mars 1969A (USSR) launched March 27, 1969. The Mars orbiter did not reach Earth orbit.
- Mars 1969B (USSR) launched April 2, 1969. The Mars orbiter failed during launch.
- Mariner 8 (U.S.) launched May 8, 1971. The Mars orbiter failed during launch.
- Kosmos 419 (USSR) launched May 10, 1971. The Mars orbiter achieved Earth orbit only.
Also in 1971, the Soviet Union finally met with success after several attempts to reach the Red Planet. Its Mars 2 orbiter, which launched May 19, 1971, arrived on Nov. 2. However, the Mars 2 lander crashed on the surface. Mars 3, launched on May 28, 1971, arrived Dec. 3. The lander worked for only a few seconds on the surface before failing, but the orbiter worked successfully.
Surface surprise: The image of Mars changed with the arrival of Mariner 9 in November 1971. The spacecraft, which launched May 30, 1971, arrived to a huge surprise: the entire planet was engulfed in a dust storm. What's more, something appeared to be poking above the plumes. When the debris settled to the surface, scientists discovered those features were the top of dormant volcanoes. Mariner 9 also discovered a huge rift across the surface of Mars that was later called Valles Marineris — after the spacecraft that discovered it. Mariner 9 spent nearly a year orbiting the Red Planet, and returned 7,329 photos.
1970s-1980s: Landings on Mars, and attempts to reach Phobos
It was clear that Mars was a very different planet than Earth, which sparked several more missions to the Red Planet. The Soviet Union continued its “Mars” series of spacecraft, but only met with partial success; one orbiter and one lander briefly returned data in 1974:
- Mars 4 launched July 21, 1973. The failed Mars orbiter flew past Mars on Feb. 10, 1974.
- Mars 5 launched July 25, 1973. The Mars orbiter arrived on Feb. 12, 1974, but lasted only a few days.
- Mars 6 launched Aug. 5, 1973. The Mars flyby module and lander arrived on March 3, 1974, but the lander failed due to a fast impact.
- Mars 7 launched Aug. 9, 1973. The Mars flyby module and lander arrived on March 3, 1974, but the lander missed the planet.
Viking missions: NASA, meanwhile, sent two pairs of orbiters and landers towards Mars in 1975. Viking 1 and Viking 2 both successfully arrived in 1976, sending a lander each to the surface while the orbiter remained working above. Viking represented the first extended exploration of Mars, with each spacecraft lasting years and transmitting reams of information.
- Viking 1 launched Aug. 20, 1975. The Mars orbiter operated from June 1976 to 1980 and the lander operated from July 1976 to 1982.
- Viking 2 launched Sept. 9, 1975. The Mars orbiter operated from Aug. 1976 to 1987, and the lander operated from Sept. 3, 1976, to 1980. Combined, the Viking orbiters and landers returned more than 50,000 photos.
Hopes for life, however, were dashed when the probes could not definitively prove the existence of microbes on the surface. (The results remain controversial today, as more is now understood about microbial activity.) Another large result of Viking came from measurements of the local atmosphere; it turned out the composition was almost identical to certain meteorites found on Earth. This proved that some meteorites found on Earth were originally from Mars.
The Soviet Union also made attempts to reach one of the moons of Mars, Phobos, in the 1980s. Both missions failed.
- Phobos 1 launched July 7, 1988. The Mars orbiter and Phobos lander were lost in August 1988 en route to Mars.
- Phobos 2 launched July 12, 1988. The Mars orbiter and Phobos lander were lost in March 1989 near Phobos.
1990s: Better, faster, cheaper
NASA's next attempt to reach the Red Planet came in the 1990s, when Mars Observer launched to the planet on Sept. 25, 1992. It was lost just before it was supposed to achieve orbit on Aug. 21, 1993. While the loss of communication could never be fully explained, the most likely cause was identified as a fuel tank rupture that caused the spacecraft to spin and lose contact with Earth.
The loss was especially painful because the spacecraft had cost so much; in 1990s dollars, it was supposed to cost $212 million. The final tally was estimated at $813 million. This was one of the factors that sparked a new move within NASA to create “better, faster, cheaper” (FBC) missions that would take advantage of advanced computer electronics and new team management techniques to reduce costs.
In the meantime, the Mars Global Surveyor left Earth on Nov. 7, 1996, and arrived at Mars on Sept. 12, 1997. Its mission was extended several times until NASA lost contact with it in 2006. MGS mapped the planet from pole to pole, revealing many ancient signs of water, such as gullies and hematite (a mineral that forms in water). Its data helped NASA decide where to land rovers in 2004. MGS also took pictures of public interest, including re-imaging the famous "face on Mars."
The Soviet Union's Mars 96 mission launched on Nov. 16, 1996. However, the orbiter, two landers and two penetrators were lost after the rocket failed.
The FBC program's first mission was a great success. The Pathfinder lander and Sojourner rover arrived at Mars in July 1997. The lander was the first to use a set of airbags to cushion the landing, and Sojourner was the first rover to trundle on Mars. Pathfinder was expected to last a month and Sojourner a week, but both made it far beyond that to September 1997, when contact was lost with Pathfinder.
Japan entered the mission-to-Mars arena with Nozomi, which launched on July 4, 1998. The orbiter failed to enter orbit in December 2003.
Two other FBC missions never made it to the Red Planet. Mars Climate Orbiter, launched on Dec. 11, 1998, disappeared after arriving in September 1999, likely because one team was operating in metric units and another in imperial units. Mars Polar Lander (MPL) and two penetrators with it (called Deep Space 2), launched on Jan. 3, 1999, were also lost, probably because MPL erroneously thought it had landed and shut off its engine prematurely. After these and other failures, FBC was shelved.
2000s to present: Rovers and orbiters galore
The discovery of ancient water evidence on Mars sparked a renaissance in Mars exploration.
Mars Odyssey, launched March 7, 2001, arrived on Oct. 24, 2001. The orbiter is still conducting its extended science mission. It broke the record for longest-serving spacecraft at Mars on Dec. 15, 2010. The spacecraft has returned about 350,000 images, mapped global distributions of several elements, and relayed more than 95 percent of all data from the Spirit and Opportunity rovers.
The European Space Agency launched Mars Express/Beagle 2 on June 2, 2003. The orbiter completed its prime mission in November 2005 and is currently on an extended mission. The lander was lost on arrival on Dec. 25, 2003.
NASA's two rovers, Spirit and Opportunity, were sent to the surface of Mars in 2004. Each provided ample evidence that water once flowed on the Red Planet. While Spirit died in a sand dune in March 2010, Opportunity is still working. In 2015, it is expected to have driven a marathon's worth of distance (more than 26 miles or 41 kilometers) on Mars.
Another NASA orbiter, the Mars Reconnaissance Orbiter, launched Aug. 12, 2005. It began orbiting the planet on March 12, 2006. The spacecraft has provided data that include more than 25,000 images and 3,500 radar observations. The mission has returned more total data than produced by all previous Mars missions combined.
On Aug. 4, 2007, NASA launched a stationary lander called Mars Phoenix, which arrived at Mars on May 25, 2008, and found water ice beneath the surface. Phoenix's solar panels suffered severe damage from the harsh Martian winter, and communication with the $475 million lander was lost in November 2008. After repeated attempts to re-establish contact, NASA declared Phoenix broken and dead in May 2010.The damage was spotted in orbital photos taken at the Red Planet.
Russia made another attempt to reach Phobos with the Phobos-Grunt mission, which launched in 2011 and crashed Jan. 15, 2012, after failing to leave Earth orbit. Phobos-Grunt was also carrying China's first attempt at a Mars orbiter, along with an experiment run by the U.S.-based Planetary Society designed to study how a long journey through deep space affects micro-organisms. China wrote off its orbiter, a tiny craft called Yinghuo-1, as a total loss in mid-November 2011.
A more powerful rover called Curiosity arrived at Gale Crater in 2012 to search for signs of ancient habitable environments. Its major findings include finding previously water-soaked areas, detecting methane on the surface, and finding organic compounds (considered the building blocks of life.) Its design has inspired another rover, temporarily called Mars 2020, which will do more advanced investigations when it arrives.
MAVEN (Mars Atmosphere and Volatile EvolutioN), launched in November 2013, achieved orbit on Sept. 21, 2014, and is looking at changes in the atmosphere of Mars to better understand why it thinned over billions of years. [Related: NASA's New Mars Probe Snaps 1st Red Planet Images]
India became the latest nation to successfully arrive at Mars in 2014, when MOM (Mars Orbiter Mission) successfully arrived in orbit. The spacecraft is far enough from the Red Planet to image the entire disc, and it has transmitted several images back to Earth that were subsequently released to the public.
For its part, the European Space Agency plans to return to Mars with two missions later this decade. The ExoMars program, which is done in conjunction with Russia, will see an orbiter (the Trace Gas Orbiter) and simple lander launched in 2016. A rover is planned to leave Earth in 2018.