Mars: the history of discovery and exploration, from the first observations to modern missions

Mars is one of the most mysterious and attractive planets in the Solar System. It is called the Red Planet because of its rusty color caused by iron oxide on the surface. Mars is the fourth planet from the Sun and the second smallest in size after Mercury. Its diameter is about 6,800 km, which is roughly half that of Earth. Mars has two small moons – Phobos and Deimos, which resemble asteroids.

Humanity has always been interested in Mars, as it is the closest planet to Earth that potentially could harbor life. Mars was known to ancient civilizations, who observed it with the naked eye and gave it different names. Over time, astronomers improved their tools and methods for studying Mars, unveiling more of its secrets. In this article, we will tell you how the discovery and study of Mars progressed from antiquity to the present day.

 

The Discovery of the Planet Mars

Formation and Age of the Planet Mars

According to modern scientific data, the planet Mars formed about 4.6 billion years ago as a result of the compression of cosmic dust and gas around the Sun. This process is called accretion and it led to the formation of all the planets in the Solar System.

Mars, like Earth, has undergone many collisions with other bodies, which affected its shape, structure, and climate. One of these collisions, which occurred about 4.1 billion years ago, created the huge Borealis basin, which occupies nearly half of the northern hemisphere of Mars. Another collision, which occurred about 4 billion years ago, caused a volcanic eruption that formed the highest mountain in the Solar System — Olympus Mons. Its height reaches 22 km, which is 3 times taller than Mount Everest.

 

The Origin of the Name of the Planet Mars

The planet Mars was named after the Roman god of war, as its red color was associated with blood and battles. The ancient Greeks called this planet Ares, after their god of war. Other cultures also gave Mars different names related to its color or character. For example, the Egyptians called it Hor-deshir, meaning “the red one,” the Babylonians — Nergal, meaning “the god of fire and destruction,” the Indians — Angaraka, meaning “the fiery one,” and the Chinese — Huoxing, meaning “the fire star.”

 

Date of the First Telescopic Observation of Mars

The first telescopic observation of Mars was made by the Italian astronomer Galileo Galilei in 1610. He used his homemade telescope, which allowed for 20x magnification. Galileo noted that Mars had phases, like the Moon, meaning it changed shape depending on its position relative to the Sun and Earth.

 

Orbital Position of the Planet Mars

The planet Mars is located about 228 million kilometers from the Sun and has an average orbital speed of about 24 km/s. Its orbit is elliptical, so the distance between Mars and the Sun changes during the year. The minimum distance, called perihelion, is about 207 million kilometers, and the maximum, called aphelion, is about 249 million kilometers. The orbital period of Mars, or the time it takes to complete one orbit around the Sun, is 687 Earth days, which is almost two Earth years.

 

Visibility of the Planet Mars in the Night Sky

The planet Mars is one of the brightest objects in the night sky. Its visibility depends on its position relative to Earth and the Sun. When Mars is on the opposite side of the Sun, it reaches its maximum brightness and is called opposition Mars. At this time, it is visible all night and appears yellow-orange in color. When Mars is on the same side as the Sun, it is called conjunction Mars and is almost invisible, as it blends with the sunlight. Opposition occurs approximately every 26 months, while conjunction happens about every 15 months.

 

Exploration of Mars in the 17th–18th Centuries

First Telescopic Observations of Mars in Antiquity and the Middle Ages

Although Mars was known to ancient civilizations, telescopic observations of it began only in the 17th century, when the telescope was invented. Before that, astronomers observed Mars with the naked eye and recorded its movement across the starry sky. They compiled catalogs and tables of Mars' position, which were used for astrology and calendars. For example, the ancient Babylonians observed Mars from the 7th century BC and created the first mathematical model of its motion.

Ancient Greeks, such as Ptolemy, Aristotle, and Hipparchus, also studied Mars and tried to explain its retrograde motion, that is, its apparent backward motion across the starry sky. They assumed that Mars moved in small circles, called epicycles, around larger circles, called deferents, which in turn revolved around Earth. This model was called geocentric and it dominated astronomy until the 16th century.

 

Discoveries by Galileo Galilei

The first astronomer to use a telescope to observe Mars was Galileo Galilei. He made his first observation in 1610 and noted that Mars had phases, like the Moon. This was an important discovery, as it confirmed the heliocentric model of the Solar System proposed by Nicolaus Copernicus, in which the planets orbit the Sun, not the Earth.

Galileo also tried to measure the size and distance of Mars, but his results were inaccurate due to the low quality of his telescope and the difficulty of determining parallax, that is, the angular displacement of the planet when observed from different points on Earth. Galileo continued observing Mars until 1638, when he lost his eyesight.

 

Discoveries of Other Astronomers (Johannes Hevelius, Giovanni Cassini)

After Galileo, other astronomers also used telescopes to study Mars and made new discoveries. For example, Dutch astronomer Johannes Hevelius in 1659 made the first detailed map of Mars, marking dark and light areas on the planet's surface. He also named them after Earth-related geography, such as Arabia, Libya, Syria, and more. He measured Mars' rotation period around its axis, which is 24 hours, 37 minutes, and 22 seconds. This value is very close to the modern figure of 24 hours, 37 minutes, and 23 seconds.

Another important astronomer who studied Mars was the Italian Giovanni Cassini. In 1666, he discovered that Mars has an axial tilt of about 25 degrees. This means that Mars has seasons like Earth, but they are longer due to its larger orbital period. Cassini also determined the distance between Mars and Earth using parallax and obtained a value of about 140 million kilometers, which was twice Galileo’s estimate.

 

Exploration of Mars in the 19th Century

Discovery of Martian Moons

One of the most significant discoveries in the history of Mars exploration was the discovery of its two moons — Phobos and Deimos. This discovery was made by American astronomer Asaph Hall in 1877 using a 66-centimeter refractor located at the Washington Observatory.

Hall searched for Martian moons after the French astronomer Camille Flammarion suggested they might exist. Hall named the moons after the sons of Mars in Greek mythology — Phobos, the god of fear, and Deimos, the god of terror.

Phobos is the closest moon to Mars, with a distance of about 6,000 km from the planet and a diameter of about 22 km. Deimos is farther from Mars, with a distance of about 20,000 km and a diameter of about 12 km. Both moons have irregular shapes and resemble asteroids. They orbit Mars faster than the planet rotates on its axis, causing them to rise and set twice a day.

 

Discovery of Canals on Mars

Another famous discovery in the 19th century was the discovery of canals on Mars. This discovery was made by Italian astronomer Giovanni Schiaparelli in 1877, when he observed Mars during its opposition. Schiaparelli saw thin lines on Mars' surface, which he called “canali” (Italian for channels or streams). He hypothesized that these could be natural or artificial water channels, possibly indicating the presence of life on the planet.

Schiaparelli created a map of Mars, marking around 40 channels, and gave them names associated with mythology and history, such as Ganges, Nile, Pharaoh, Eridanus, and others.

His discovery sparked great interest and debate in the scientific world. Many astronomers tried to confirm or refute the existence of canals on Mars, but not all could see them due to low telescope resolution or atmospheric interference.

One of the most famous supporters of the canal theory was American astronomer Percival Lowell, who in 1894 founded his own observatory in Arizona, specifically for studying Mars. He observed Mars for 15 years and drew over 500 canals, which he believed were evidence of an advanced civilization on the planet. He also wrote several books describing his theories and fantasies about Martians who built canals to irrigate their arid lands. His books became popular and inspired many science fiction writers, such as H.G. Wells, Ray Bradbury, Arthur C. Clarke, and others.

However, in the 20th century, the canal theory on Mars was debunked by more advanced telescopes and space probes, which found no evidence of water or life on the planet. It turned out that the canals were an illusion caused by optical distortions, psychological factors, and a lack of knowledge about Mars' terrain. In reality, Mars' surface only has natural landforms, such as valleys, channels, ridges, and volcanoes, which can create the impression of linear structures at low resolution.

 

Publication of the First Map of Mars

In 1877, the same year Schiaparelli discovered canals on Mars, the first map of Mars based on telescopic observations was published. This map was created by French astronomer Camille Flammarion, who was a supporter of the canal and life on Mars theories. He used data obtained from Schiaparelli and other astronomers and drew a map showing the locations of canals, seas, continents, and islands on Mars. He also gave them names associated with mythology, history, and literature, such as Atlantis, Eden, Utopia, El Dorado, and others.

His map was widely distributed and influenced public opinion about Mars. However, his map was also inaccurate and fantastical, as it did not take into account the planet's real terrain and climate. For example, he depicted large bodies of water on Mars that do not actually exist and assigned them colors that did not match reality. His map was soon refuted by more accurate maps drawn by other astronomers, such as Eugène Michel Antoniadi, Edward Emerson Barnard, and William Wallace Campbell.

 

Other Astronomical Discoveries

In the late 19th and early 20th centuries, astronomers continued to study Mars and make new discoveries. For example, in 1892, American astronomer William Henry Pickering discovered that Mars has an atmosphere, which consists mainly of carbon dioxide. He also measured the atmospheric pressure on Mars, which is about 6 millibars, or 160 times less than on Earth.

In 1909, American astronomer Carl Lamont discovered that Mars has polar ice caps that change in size depending on the season. He hypothesized that they consist of ice and snow, but later it was found that they also contain dry ice, or frozen carbon dioxide.

In 1911, American astronomer Vesto Melvin Slipher discovered that Mars has its own magnetic field, although it is very weak and cannot protect the planet from the solar wind.

In 1924, American astronomer John Adam Fleming discovered that Mars emits radio waves that can be detected on Earth. He suggested that this could be due to electrical activity in Mars' atmosphere or possible signals from a Martian civilization. However, it was later determined that the radio waves are caused by thermal radiation from Mars' surface and carry no information.

 

Exploration of Mars in the 20th Century

Exploration of Mars Using a Spectrometer

In the 20th century, astronomers began using new methods and tools to study Mars, allowing them to obtain more accurate and detailed information about the planet. One such tool was the spectrometer, which measures the spectrum of light reflected or emitted by an object. The light spectrum contains information about the chemical composition, temperature, pressure, and other properties of the object.

Using the spectrometer, astronomers were able to determine that Mars lacks free oxygen, water, or organic compounds, indicating its uninhabitable nature. They also identified the presence of elements such as iron, magnesium, aluminum, silicon, calcium, sodium, and others on Mars.

Astronomers also discovered that Mars has an ozone layer, which absorbs the Sun's ultraviolet radiation, but it is very thin and ineffective.

Spectrometry also allowed scientists to study the dynamics of Mars' atmosphere, including its temperature, pressure, winds, clouds, dust storms, and other phenomena.

 

First Attempts to Reach Mars

In the 20th century, not only astronomers but also scientists, engineers, and explorers became interested in Mars and tried to reach it using space probes. The first attempts were made in the 1960s, when the Soviet Union and the United States launched several interplanetary stations to fly to Mars and capture photographs, measurements, and analyses. However, most of these missions ended in failure due to various technical problems, such as malfunctions, loss of communication, deviations from course, and more.

For example, of the 10 Soviet interplanetary stations launched between 1960 and 1964, only one, Mars-1, managed to follow a trajectory towards Mars but lost communication with Earth at a distance of 106 million kilometers from the planet.

Of the 7 American interplanetary stations launched between 1964 and 1969, only two, Mariner 4 and Mariner 6, reached Mars and took pictures of it, but they were of poor quality and provided little information about the planet.

 

First Successful Mission to Mars

The first successful mission to Mars was the American interplanetary station Mariner 7, launched on March 27, 1969, and reaching Mars on August 5, 1969. It took 126 pictures of the Martian surface, revealing its craters, ridges, valleys, and polar caps. It also measured the temperature, pressure, density, and composition of the Martian atmosphere and detected the presence of water vapor and carbon dioxide in it.

This mission determined the mass, radius, and gravity of Mars, as well as its magnetic field and radio emissions. Its data helped clarify knowledge about Mars and debunk some myths and fantasies about the planet. For example, it showed that Mars does not have canals, seas, vegetation, or living creatures, but only a dry, cold, and lifeless desert. It also showed that Mars is more like the Moon than Earth, as it has many craters from meteorites and lacks a global magnetic field.

The Mariner 7 mission was an important step in Mars exploration and paved the way for more complex and advanced missions in the future.

 

Exploration of Mars Using Automated Interplanetary Stations

In the 1970s, a new era of Mars exploration began when the first automated interplanetary stations were launched, which not only flew past Mars but also entered its orbit and landed on its surface. These stations allowed for more detailed and high-quality images of Mars, as well as conducting various scientific experiments and studies.

Among these stations were the Soviet Mars 2, Mars 3, Mars 5, Mars 6, and Mars 7, and the American Mariner 9, Viking 1, Viking 2, and others. They made many discoveries and achievements, which we will discuss further.

 

Soviet Stations Mars 2 and Mars 3

Mars 2 and Mars 3 became the first stations to reach Mars' orbit in 1971. They took over 60 pictures of Mars' surface, showing its terrain, geology, climate, and atmosphere. They also launched landing modules, which became the first objects to reach the Martian surface.

However, Mars 2 lost communication upon landing and crashed, while Mars 3 operated on the Martian surface for only 20 seconds before losing communication. They were unable to transmit any data from the Martian surface, except for one blurry image.

 

American Automatic Interplanetary Station Mariner 9

Mariner 9 became the first American station to reach Mars' orbit in 1971. It took over 7,000 pictures of Mars' surface, revealing its diversity and complexity.

Its images showed huge volcanic formations (such as Olympus Mons — the largest volcano discovered in the Solar System) and canyons (including Valles Marineris — a giant canyon system over 4,000 kilometers long, named in honor of the scientific achievements of this interplanetary station). The images also showed dried riverbeds, craters, signs of wind and water erosion, and shifting layers, weather fronts, fog, and many other interesting details.

Mariner 9 also studied Mars' atmosphere, its composition, temperature, pressure, clouds, dust storms, and more. It was discovered that Mars has two types of polar caps: permanent ones made of dry ice and seasonal ones made of water ice and snow.

 

The Viking Program

This space program included the launch of two identical American probes, Viking 1 and Viking 2. They became the most successful and advanced space stations to reach Mars' orbit and surface in 1976. They took over 50,000 pictures of Mars' surface, showing its detailed features and colors. They were the first to send high-quality color photos from the Martian surface. The images showed a desert landscape with reddish soil scattered with rocks. The sky was pink due to light scattered by red dust particles in the atmosphere.

Viking 1 and Viking 2 also launched landing modules, which became the first objects to successfully land on the Martian surface and operate for several years. They transmitted more than 1,400 images from the Martian surface, showing its landscape, weather, and more.

These probes conducted several scientific experiments, including searching for life on Mars. They measured the chemical composition of Mars' soil, air, and water, and detected the presence of organic molecules but found no signs of living organisms. Seismic activity, magnetic fields, radiation, and other phenomena were also studied.

Viking 1 and Viking 2 significantly expanded knowledge of Mars and stimulated further exploration of the planet.

 

Exploration of Mars in the 21st Century

Exploration of Mars Using Rovers

In the late 20th and early 21st centuries, Mars exploration reached a new level when the first rovers were launched, capable of moving across Mars' surface and exploring various locations and objects. These rovers were equipped with various scientific instruments such as cameras, spectrometers, lasers, drills, microscopes, and more. They could also communicate with Earth and transmit their data and images.

Among these rovers were the American Spirit, Opportunity, Curiosity, Perseverance, and others. They made many discoveries and achievements, which we will briefly mention now.

 

Spirit and Opportunity Rovers

Spirit and Opportunity were the first American rovers to reach Mars' surface in 2004. They landed in different locations on Mars and explored them for several years. They took over 300,000 pictures of Mars' surface, showing its diverse landscape.

The rovers discovered traces of water, minerals, meteorites, volcanic activity, and more. They studied the climate, weather, magnetic fields, and radiation on Mars. They also collected and analyzed samples of soil and rocks on Mars and conducted several scientific experiments.

Spirit and Opportunity are rovers of the same model. They operated much longer than planned, thanks to the natural cleaning of their solar panels by the Martian wind. These rovers significantly increased knowledge about Mars and became the longest-lived and most successful rovers in history.

On May 1, 2009, the Spirit rover became stuck in a sand dune. This was not the first such situation with rovers, and over the following eight months, efforts were made to free it. On January 26, 2010, NASA announced that the rover was hindered by its location in soft soil. Until March 22, 2010, the rover continued to be used as a stationary platform, after which communication was lost. On May 24, 2011, NASA announced that efforts to reestablish contact with the rover had failed, and it remained silent. A farewell to the Spirit rover was held at NASA headquarters and broadcast on NASA TV. Spirit operated on Mars for 6 years and 2 months, 21.6 times longer than planned.

During its time on Mars, the Opportunity rover traveled over 45 kilometers, relying solely on solar panels for power. On June 12, 2018, the rover entered sleep mode due to a prolonged and powerful dust storm that prevented light from reaching its solar panels. It never regained contact. On February 13, 2019, NASA officially announced the end of the Opportunity mission. The rover operated on Mars for 14 years and 8 months, exceeding its planned service life by 55 times.

 

Curiosity Rover

Curiosity became the largest and most complex American rover, which reached the Martian surface in 2012. It landed in Gale Crater and is still exploring it today. It has taken over 500,000 pictures of Mars' surface, showing its detailed features and colors.

Curiosity is an autonomous chemical laboratory, several times larger and heavier than previous rovers. It discovered organic molecules on Mars that may be related to the origin of life. It also measured the chemical composition, temperature, pressure, humidity, and other atmospheric parameters on Mars. It studied the geology, geochemistry, mineralogy, hydrology, and more. The rover collected and analyzed soil and rock samples on Mars and conducted several scientific experiments.

Curiosity was the first rover to take a self-portrait (selfie) on Mars, as well as the first rover to record sound on Mars. It continues to explore Mars and transmit its data and images to Earth.

 

Perseverance Rover

Perseverance became the newest and most advanced American rover, which reached the Martian surface in 2021. It landed in Jezero Crater and is currently exploring it. It has taken many pictures of the Martian surface and conducted reconnaissance operations. As of January 2024, the rover has traveled over 40 km.

Perseverance was the first rover to bring a helicopter to Mars, named Ingenuity, which became the first aircraft to fly on another planet. It was also the first rover to record a video on Mars and the first rover to record the sound of Martian wind. It continues to explore Mars and transmit its data and images to Earth.

 

Exploration of Mars Using Orbital Stations

In the 21st century, Mars exploration continues with the help of orbital stations that fly around Mars, taking pictures, measurements, and analyses. These stations provide a global and dynamic picture of Mars, as well as support communication with rovers and helicopters on the planet's surface. Among these stations are the following:

• American: 2001 Mars Odyssey, Mars Reconnaissance Orbiter (MRO), Mars Atmosphere and Volatile Evolution (MAVEN);
• European: Mars Express, ExoMars Trace Gas Orbiter;
• Indian: Mars Orbiter Mission;
• Emirati: Emirates Mars Mission;
• Chinese: Tianwen-1.

They made many discoveries and achievements, and now we will briefly mention some of them.

 

Orbital Station “2001 Mars Odyssey”

“2001 Mars Odyssey” became the first American orbital station to reach Mars' orbit in 2001. It took over 300,000 pictures of Mars' surface, revealing its topography, mineralogy, thermal inertia, and more.

The station detected traces of water, ice, hydroxyl, and hydrogen peroxide on Mars. It also measured radiation, magnetic fields, and plasma on Mars.

“2001 Mars Odyssey” continues to operate in Mars' orbit and transmit its data and images to Earth. It is estimated to have enough fuel to operate until the end of 2025.

 

Orbital Station “Mars Reconnaissance Orbiter”

“Mars Reconnaissance Orbiter” became the most powerful and advanced American orbital station, reaching Mars' orbit in 2006. It took over 50 million pictures of Mars' surface, revealing its detailed features. This orbital station contains a range of scientific instruments, such as cameras, spectrometers, and radars, used to analyze Mars' topography, stratigraphy, minerals, and ice.

The station's weather and surface studies, search for possible landing sites, and new telecommunications system pave the way for future space missions.

The Mars Reconnaissance Orbiter's telecommunications system transmits more data to Earth than all previous interplanetary missions combined, and it can serve as a powerful orbital relay for other exploration programs.

 

Orbital Station “Mars Express”

“Mars Express” became the first European orbital station to reach Mars' orbit in 2003. It took over 10 million pictures of Mars' surface, revealing its topography, geology, mineralogy, and more.

It was the first to simultaneously measure and create distribution maps of water vapor and ozone in the atmosphere. The nighttime glow of nitric oxide, previously known on Venus, was detected for the first time on Mars. Tiny aerosol particles filling the atmosphere up to heights of 70–100 km were discovered. Water ice was found in the southern polar cap at the end of the Martian summer for the first time.

“Mars Express” detected methane in Mars' atmosphere, which may indicate the presence of life on the planet (methane cannot remain long in the Martian atmosphere, so its supply must be replenished either through the activities of microorganisms or due to geological activity).

The orbital station also discovered dense clouds of dry ice, which cast shadows on the planet's surface and even affect its climate.

 

Prospects for Mars Colonization

Colonizing Mars is a long-term and large-scale task that requires considerable effort, resources, and technology. Colonization of Mars involves not only sending humans to the planet but also establishing permanent bases, colonies, and a civilization on it. The motivation for colonizing Mars includes scientific, economic, political, cultural, and other factors. Colonizing Mars also faces various problems and risks, such as technical, financial, legal, and others.

Currently, the colonization of Mars is one of the main goals and tasks of many countries and organizations that are developing and implementing various plans and projects aimed at achieving this goal. Among these plans and projects, the following are the most significant.

 

NASA

NASA is the American space agency with a long history of exploring and studying Mars. NASA has launched numerous spacecraft, rovers, and helicopters to Mars, making many discoveries and achievements. NASA is also developing and preparing new missions to Mars, aimed at further studying the planet and preparing for the landing of the first humans on Mars.

NASA plans to send the first astronauts to Mars in the 2030s, as well as establish a permanent base on Mars that will serve as a platform for further exploration of the planet. NASA is also collaborating with other countries and organizations, such as the European Space Agency (ESA), the Canadian Space Agency (CSA), the Russian Space Agency (Roscosmos), and others, as part of international cooperation in the exploration and colonization of Mars.

 

SpaceX

SpaceX is an American private space company with ambitious plans for colonizing Mars. SpaceX develops and builds its own rockets, spacecraft, and satellites, which can deliver people and cargo to Mars and return them to Earth.

SpaceX is developing and testing its super heavy launch vehicle Starship, which is expected to be the main means of colonizing Mars. SpaceX plans to launch the first unmanned missions to Mars in 2024, as well as the first manned missions to Mars in 2026. The company also plans to establish a large colony on Mars, with a population of millions, which will be independent of Earth.

SpaceX collaborates with NASA and other organizations, such as the Japan Aerospace Exploration Agency (JAXA) and the Australian Space Agency (ASA), as part of commercial and scientific cooperation in the exploration and colonization of Mars.