This illustration shows NASA’s Perseverance rover casting off its spacecraft’s cruise stage, minutes before entering the Martian atmosphere. (Image: NASA/JPL-Caltech)

Since the dawn of the space race, the idea of sending humans to Mars has been the subject of aerospace engineering and scientific studies. From the successful flyby of NASA’s Mariner 4 in 1964 to the Perseverance rover in 2020, the missions to Mars have come a long way.

New images taken by the Perseverance rover recently may show signs of what was once a rollicking river on Mars, one that was deeper and faster moving than scientists have ever seen evidence for in the past. The river was part of a network of waterways that flowed into Jezero Crater, the area the rover has been exploring since landing more than two years ago. Stitched together from hundreds of images captured by Perseverance’s Mastcam-Z instrument, two new mosaics reveal important clues: coarse sediment grains and cobbles.

“Those indicate a high-energy river that’s truckin’ and carrying a lot of debris. The more powerful the flow of water, the more easily it’s able to move larger pieces of material,” said Libby Ives, a Postdoctoral Researcher at NASA’s Jet Propulsion Laboratory, which operates the Perseverance rover. With a background in studying Earth-based rivers, Ives has spent the last six months analyzing images of the Red Planet’s surface.

This infographic shows the location of every successful mission that has landed on Mars. (Image: The Planetary Society)

Overall, there have been 50 missions to Mars, out of which 10 have landed successfully on Mars — and nine of these have been from NASA. Here’s a look at all the successful missions to Mars through the past decades that have paved the way to future exploration of the Red Planet.

Mariner 3 and 4: 1964

Mariner 3 and 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, and Mariner 3 did not get to Mars. Three weeks later, on November 28, 1964, Mariner 4 was launched successfully on an eight-month voyage to the Red Planet. The spacecraft flew past Mars on July 14, 1965, collecting the first close-up photographs of another planet. It was not expected to survive much longer than the eight months to its Mars flyby encounter, but lasted about three years in solar orbit, continuing long-term studies of the solar wind environment.

Mariner 6 and 7: 1969

NASA’s Mars 2020 Perseverance rover and NASA’s Ingenuity Mars Helicopter (shown in an artist’s concept) are the agency’s two newest explorers on Mars. Perseverance is the most sophisticated rover NASA has ever sent to Mars. Ingenuity, a technology experiment, is the first aircraft to fly on another planet.

Mariner 6 and 7 were the second pair of Mars missions in NASA’s Mariner series of solar system exploration in the 1960s and early 1970s. In 1969, Mariner 6 and Mariner 7 completed the first dual mission to Mars, flying by over the equator and south polar regions and analyzing the Martian atmosphere and surface with remote sensors, as well as recording and relaying hundreds of pictures. Their approach pictures showed that the dark features on the surface long seen from Earth were not canals, as once interpreted in the 1800s.

Mariner 8 and 9: 1971

Mariner 8 and 9 were the third and final pair of Mars missions in NASA’s Mariner series. Both were designed to be the first Mars orbiters, marking a transition in our exploration of the Red Planet from flying by the planet to spending time in orbit around it. Unfortunately, Mariner 8 failed during launch on May 8, 1971. Mariner 9 was launched successfully on May 30, 1971, and became the first artificial satellite of Mars when it arrived and went into orbit, where it functioned in Martian orbit for nearly a year. It proceeded to reveal a very different planet than expected — one that boasted gigantic volcanoes and a grand canyon stretching 3,000 miles across its surface. It exceeded all primary photographic requirements by photo-mapping 100 percent of the planet’s surface.

Viking 1 and 2: 1976

NASA’s Perseverance Mars rover captured this mosaic of a hill nicknamed “Pinestand.” Scientists think the tall sedimentary layers stacked on top of one another here could have been formed by a deep, fast-moving river. (Image: NASA/ JPL-Caltech/ASU/MSSS)

NASA’s Viking Project became the first U.S. mission to land a spacecraft safely on the surface of Mars in 1976 and return images of the surface. Two identical spacecraft, each consisting of a lander and an orbiter, were built. Each orbiter-lander pair flew together and entered Mars orbit; the landers then separated and descended to the planet’s surface. The Viking missions conducted three biology experiments to look for possible signs of life and discovered chemical activity in the Martian soil. The orbiters continued imaging and performing other scientific operations from orbit while the landers deployed instruments on the surface. The mission was considered successful and is credited with helping to form most of the body of knowledge about Mars through the late 1990s and early 2000s.

Mars Global Surveyor: 1996

Mars Global Surveyor operated in orbit around Mars for nine years and 52 days, longer than any other spacecraft in history, and for more than four times as long as the prime mission originally planned. The spacecraft returned detailed information that has overhauled understanding about Mars. A few of the mission’s many important discoveries about Mars include before-and-after images revealing bright new deposits in two gullies on Mars suggest liquid water has carried sediment down them in the past seven years. These pictures are the strongest evidence to date that water still flows occasionally on the surface of Mars, in brief episodes.

Mars Pathfinder: 1997

Illustration of the ESCAPADE spacecraft in orbit around Mars. (Image: Rocket Lab USA/UC Berkeley)

Mars Pathfinder was designed to be a demonstration of the technology necessary to deliver a lander and a free-ranging robotic rover to the surface of Mars in a cost-effective and efficient manner. The lander, formally named the Carl Sagan Memorial Station following its successful touchdown, and the rover, named Sojourner after American civil rights crusader Sojourner Truth, both outlived their design lives — the lander by nearly three times, and the rover by 12 times. Mars Pathfinder returned 2.3 billion bits of information, including more than 16,500 images from the lander and 550 images from the rover, as well extensive data on winds and other weather factors.

Mars Odyssey: 2001

The 2001 Mars Odyssey was an orbiting spacecraft designed to determine the composition of the planet’s surface, to detect water and shallow buried ice, and to study the radiation environment. Since NASA launched the 2001 Mars Odyssey Orbiter to the Red Planet almost 22 years ago, the spacecraft has looped around Mars more than 94,000 times. The spacecraft has mapped minerals across the Martian surface, allowing scientists to better understand the planet’s history. Odyssey has found ice deposits that could be used by future astronauts. It studied radiation that could harm those same astronauts and scouted potential landing sites for missions to come.

Mars Exploration Rovers (Spirit and Opportunity): 2004

Two powerful Mars rovers are on the Red Planet. They have far greater mobility than the 1997 Mars Pathfinder rover. Each rover carries a sophisticated set of instruments to search for evidence of liquid water that may have been present in the planet’s past. The rovers are identical to each other but are exploring different regions of Mars. The rovers have returned an incomprehensible amount of data. In addition, both vehicles lasted much longer than expected. Spirit was sand trapped in 2009, after attempting to free it, scientists were eventually forced to abandon the campaign. Opportunity was active in Mars from 2004 until 2018. The primary mission for these rovers was to explore the Martian surface and conduct geological experiments.

Mars Reconnaissance Orbiter: 2005

NASA’s Mars Reconnaissance Orbiter (MRO) is capturing unique views of Mars with the most powerful telescopic camera ever to another planet. Its five other scientific instruments are collecting data about the Red Planet. Findings from MRO provided the strongest evidence that liquid water flows intermittently on present-day Mars. Using an imaging spectrometer on MRO, researchers detected signatures of hydrated minerals on slopes where mysterious streaks are seen on the Red Planet. These darkish streaks appear to ebb and flow over time. They appear in several locations on Mars when temperatures are above -10° F and disappear at colder times.

Phoenix Scout: 2007

This illustration shows a concept for multiple robots that would team up to ferry to Earth samples of rocks and soil being collected from the Martian surface by NASA’s Mars Perseverance rover. (Image: NASA)

The Phoenix Mars Lander successfully landed on the north polar region of Mars. Its mission is to dig up and analyze icy soil. The mission was the first chosen for NASA’s Scout program, an initiative for smaller, lower cost, competed spacecraft. Named for the resilient mythological bird, Phoenix uses a lander that was intended for use by 2001’s Mars Surveyor lander prior to its cancellation. It also carried a complex suite of instruments that are improved variations of those that flew on the lost Mars Polar Lander. In August 2008, Phoenix completed its three-month mission studying Martian ice, soil, and atmosphere. The lander worked for two additional months before reduced sunlight caused energy to become insufficient to keep the lander functioning.

Mars Science Laboratory (Curiosity): 2011

The Mars Science Laboratory Curiosity rover was aimed to assess whether Mars ever had an environment able to support small life forms called microbes. In other words, its mission is to determine the planet’s “habitability.” Mars Science Laboratory was also intended to be the first planetary mission to use precision landing techniques, steering itself toward the Martian surface, similar to the way the space shuttle controls its entry through Earth’s upper atmosphere. In this way, the spacecraft would fly to a desired location above the surface of Mars before deploying its parachute for the final landing. Curiosity has collected soil samples and rocks and analyzed them for organic compounds and environmental conditions that could have supported microbial life now or in the past.

Mars Atmosphere and Volatile Evolution (MAVEN): 2013

The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft launched in November 2013 and entered Mars’ orbit in September 2014. The mission’s goal is to explore the planet’s upper atmosphere, ionosphere, and interactions with the Sun and solar wind to explore the loss of the Martian atmosphere to space. MAVEN is the only asset at Mars able to observe the Sun’s activity and the response of the thin Martian atmosphere at the same time. Real-time analysis and simulations of the solar eruptions from NASA’s Moon to Mars Space Weather Analysis Office also allowed the MAVEN team to correctly predict when the developing solar storm would reach the Red Planet.

Insight: 2018

InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport) was a proposed NASA Discovery Program mission for placing a single geophysical lander on Mars to study its deep interior. InSight’s two-year mission was to study the deep interior of Mars to learn how all celestial bodies with rocky surfaces, including Earth and the Moon, formed. It landed on the Elysium Planitia region of Mars and has been investigating processes that shaped the rocky planets of the inner solar system more than four billion years ago. While NASA retired its InSight Mars lander in December 2022, the trove of data from its seismometer will be useful for decades to come.

Perseverance: 2020

Perseverance is a car-sized Mars rover designed to explore the Jezero crater on Mars as part of NASA’s Mars 2020 mission. Perseverance has a similar design to its predecessor rover, Curiosity, although it was moderately upgraded. It carries seven primary payload instruments, 19 cameras, and two microphones. The rover also carried the mini helicopter Ingenuity to Mars, an experimental aircraft and technology testbed that made the first powered flight on another planet on April 19, 2021. As of April 13, 2023, it has made 50 successful flights and continues to break its own records for speed, distance, and altitude. A few days after landing it released the first audio recorded on the surface of Mars, capturing the sound of Martian wind.

One important function of the Perseverance rover has been to collect and cache samples of Mars rock and atmosphere. Currently in progress is planning and development for the Mars Sample Return Campaign. This campaign would involve multiple spacecraft to pick up the samples, launch a rocket to carry them into Mars orbit and rendezvous with a homeward-bound craft to carry the precious cargo safely down to Earth. Once on Earth, the samples would be analyzed in laboratories with sophisticated equipment too large and heavy for transport to Mars. Scientists for generations to come would use the samples to help determine whether life has ever existed on Mars, and even whether it still exists.

NASA has ambitious plans to continue studying Mars, using the latest technologies and knowledge as well as to send humans to Mars sometime in the future. The first crewed Mars Mission, which would include sending astronauts to Mars, orbiting Mars, and a return to Earth, is proposed for the 2030s.

Meanwhile, the agency is developing technologies that will enable reaching the Red Planet and living on it as safely as possible. The key technologies that are being tested include powerful propulsion systems including nuclear electric and thermal propulsion, an inflatable heat shield, hi-tech Martian space suits, automated transfer vehicles, laser communications, and reliable power supply.

NASA is also aiming to radically reduce the price tag for exploring Mars with a small satellite mission called ESCAPADE (Escape and Plasma Acceleration and Dynamics Explorers). The mission, led by the UC Berkeley Space Sciences Laboratory, is a twin-spacecraft Class D mission dedicated to studying the transfer of solar wind energy and momentum through Mars’ unique hybrid magnetosphere and how it drives ion and sputtering escape. ESCAPADE will launch on Blue Origin’s New Glenn rocket from Space Launch Complex-36 at Cape Canaveral Space Force Station in Florida.

ESCAPADE will study Mars’ magnetosphere — the magnetized area of space around the planet — using two identical small spacecraft, which will provide simultaneous two-point observations. The spacecraft will help provide researchers a better understanding of how the magnetosphere interacts with the solar wind, and how energy and plasma enter and leave the magnetosphere. Each satellite will carry three instruments: a magnetometer for measuring magnetic field, an electrostatic analyzer to measure ions and electrons, and a Langmuir probe for measuring plasma density and solar extreme ultraviolet flux.

For more than five decades, NASA has had a fleet of spacecraft orbiters, landers, and rovers exploring Mars from various vantage points. This approach to exploration has already dramatically increased our knowledge of the planet and will continue to do so into the coming years and decades.