1. Mariner 4
Mariner 4 was the first spacecraft to successfully fly by Mars, producing the first photos of another planet that were taken from space. The photos revealed impact craters similar to the Moon’s, which were just starting to be photographed at close range. What was expected to be an eight-month journey lasted about three years, as Mariner 4 continued its investigations in solar orbit.
2. Mariner 6
Mariner 6 and Mariner 7 were identical spacecraft that completed the first successful dual mission to Mars. The goal was to perform a close flyby of Mars in order to gain further knowledge of the planet’s surface and atmosphere in the service of aiding future investigations, especially those focused on the prospect of extraterrestrial life.
3. Mariner 7
Combined, Mariner 6 and Mariner 7 returned hundreds of images from both far and near encounters with Mars. 20% of the surface of Mars was revealed in close-ups; as opposed to images produced by Mars 4, these new images showed Mars’s surface to be very different from the Moon’s.
4. Mars 2
Launched by the USSR, Mars 2 and Mars 3 were identical spacecraft that each had orbiting and landing capability. The aim of Mars 2 was to investigate many aspects of the planet, including temperature, topography, atmosphere, solar wind and magnetic fields. While the Mars 2 lander failed, the orbiter returned a large amount of data to support these investigations.
5. Mars 3
As opposed to Mars 2, Mars 3 succeeded in its landing capability on December 2, 1971, making it the first spacecraft to execute a soft landing on the Martian surface. However, either the lander or the orbiter communications relay failed soon after, and only a partial panoramic image with no detail was returned. The joint mission was completed after Mars 2 had completed 362 orbits and Mars 3 had completed 20.
6. Mariner 9
Mariner 9, along with Mariner 8, was part of a dual NASA mission to be the first to orbit Mars. While Mariner 8 failed, Mariner 9 launched successfully, and on November 14, 1971, became the first spacecraft to orbit Mars, followed just weeks later by the Soviet Mars 2 orbiter. Mariner 9 continued its orbit for nearly a year, photomapping the entire surface of the planet and providing the first close-ups of the Martian moons Phobos and Deimos.
7. Viking 1
Viking 1 and Viking 2 comprised NASA’s Viking Project; each spacecraft consisted of a lander and an orbiter. On July 20, 1976, Viking 1 became the first US spacecraft to successfully land on Mars, and the first to return images from the surface. It operated on the surface of Mars for over six years, producing images, collecting data, and exploring the possibility of extraterrestrial life through biology experiments. The Viking 1 orbiter completed 1,489 orbits of Mars.
8. Viking 2
Viking 2 successfully landed on the surface of Mars, at Utopia Planitia, less than two months after its identical predecessor, Viking 1. While the investigations of the two landers yielded the discovery of inexplicable chemical activity in the Martian soil, there was no clear evidence for the existence of living microorganisms. Each Viking orbiter and lander lasted for months or years beyond the projected 90 days.
9. Mars Global Surveyor
Mars Global Surveyor (MGS) was launched as a NASA mapping mission. It orbited Mars on a circular track, studying the entire surface, atmosphere, and interior of the planet. One of the most notable findings of the Mars Orbital Camera it utilized was that Mars has repeating weather patterns, a discovery that has helped guide subsequent lander and rover missions.
Launched by NASA, Mars Pathfinder demonstrated a new way of entering the Martian atmosphere, aided by a parachute and airbags, and brought the first robotic rover, Sojourner, to Mars. After touchdown, the lander was named the Carl Sagan Memorial Station. Pathfinder returned 2.3 billion bits of information, including data that suggests Mars was at one time warm and wet.
11. Mars Odyssey
The Mars Odyssey mission is the longest-lasting of NASA’s Mars missions. Launched in 2001 and continuing its orbit today, Mars Odyssey produced the first global map of Martian surface chemical elements and minerals. It has also served as a communications relay for subsequent Mars Missions and has helped to identify landing sites for landers and rovers.
12. Mars Express
The Mars Express was the first ESA mission to another planet. The name is indicative of the expeditious pace of the spacecraft’s development, and it used technology from ESA’s Rosetta Mission and the Russian Mars ‘96 Mission. It is still in orbit today, its main objective to search for water under the Martian surface.
Spirit was one of NASA’s Mars Exploration twin rovers (Spirit and Opportunity) and the first to land on Mars, at Gusev Crater. Both rovers trekked for miles, using multiple spectrometers to yield a wealth of new information about the makeup of Martian rocks and soil and new rock abrasion tools to investigate under the surface. The rovers produced hundreds of thousands of brilliantly detailed images and evidence of past wet conditions that suggest the possibility of microbial life.
Opportunity was the second of the Mars Exploration rovers, landing less than two weeks later. It landed at Meridiani Planum, a location whose mineral deposits point to a wet history. Along with Spirit, Opportunity produced a multitude of data, as both rovers lasted for many years beyond their projected mission lifetimes. In 2015, Opportunity broke a record for extraterrestrial travel, covering a distance greater than a marathon.
Rosetta was part of ESA’s Horizon 2000 cornerstone missions; it journeyed to and orbited around comet 67P/Churyumov-Gerasimenko, the first spacecraft to orbit a cometary nucleus. Its lander, Philae, was the first to land on a comet. During Rosetta’s 10-year journey to the comet, it performed multiple gravity assist maneuvers, including a flyby of Mars that came within 155 miles of the planet.
16. Mars Reconnaissance Orbiter (MRO)
NASA’s Mars Reconnaissance Orbiter has many aims in the service of future planetary exploration missions. It uses an extremely powerful camera to study the geology and meteorology of Mars. It uses a sounder to search for subsurface water. And it facilitates communication between other spacecraft and Earth, acting as the first building block in an “interplanetary Internet.”
Phoenix was the first spacecraft used in NASA’s Scout program, a campaign to send smaller, lower-cost spacecraft to Mars. To investigate the history of water on Mars, Phoenix landed farther north than ever before, in a polar region where water ice can be found. The spacecraft contained tiny ovens and a laboratory for soil sampling. The mission lasted a little over five months.
Dawn was a NASA spacecraft with ion engines that was able to orbit two destinations–Vesta and Ceres–in the asteroid belt between Mars and Jupiter. It was the first spacecraft to visit a dwarf planet, Ceres, and the first to go into orbit around two worlds beyond Earth. In February of 2009, Dawn used a Mars gravity assist on its years-long journey to Vesta and, later, Ceres.
Roughly the size of a car, Curiosity is part of NASA’s Mars Science Laboratory mission and is the largest and most adept rover to explore the planet. Curiosity uses the most advanced instruments ever sent to Mars to investigate rock, soil, and air samples at the Gale Crater. Its radioisotope power system uses plutonium decay to generate electricity that continues to power the rover years beyond its required operating lifespan.
20. Mars Orbiter
The Mars Orbiter Mission (MOM) was the first interplanetary mission of the Indian Space Research Organisation (ISRO). The mission made India the fourth nation in the world to perform a successful journey to Mars, the first Asian nation to reach Mars, and the first nation to reach Mars on its initial attempt.
Mars Atmospheric and Volatile EvolutioN (MAVEN) was the second spacecraft employed in NASA’s Mars Scout program and is still operating today. It is the first spacecraft to directly measure elements of the Martian atmosphere. Its goal is to investigate climate change on Mars in order to explore whether the conditions were ever hospitable to life as we know it.
The ExoMars Trace Gas Orbiter (TGO) is the first mission of ESA’s ExoMars program and is a collaboration between ESA and Roscosmos. While the TGO continues its orbit around Mars today, studying the Martian atmosphere, its lander, the Schiaparelli EDL Demonstration Module, was lost on descent. NASA’s participation in the project includes precision navigation through “Electra” telecommunication radios.
InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a lander that is part of the NASA Discovery Program. It studies the deep interior of Mars in order to investigate the larger question of how terrestrial planets formed billions of years ago. MarCO-A and MarCO-B were two CubeSats, the first of their kind, that rode along with InSight, performing a flyby of Mars and transmitting data to Earth from Insight as it landed on Mars.
The Mars 2020 Perseverance Rover mission has multiple objectives as it seeks to build upon previous missions. It will search not only for signs of past habitable conditions but also for signs of actual past microbial life. It will create a “cache” of rock and soil samples that could potentially be transported to Earth in the future for further study. It will also conduct investigations relating to future human voyages to Mars, including whether oxygen can be produced from the Martian atmosphere and how other environmental conditions might affect astronauts on Mars. The rover is accompanied by the four-pound helicopter Ingenuity, which will try to execute the first controlled flight on another planet.