Mars is the fourth planet in the Sol System. It is the second smallest planet in the system, with an average radius 370 kilometers smaller than Venus. It carries the name of the roman god of war, Mars, due to its original bright red color resembling blood. Mars is the second planet to support human colonization and the first to be colonized by Humans after Earth. Since 2052, Mars has been undergoing terraforming and is expected to be fully habitable by 2450. Mars is one of five planets in the solar system visible with the naked eye, and as such was one of the first planets to be discovered by human civilization, with the first records of the planet being from around 2700 BC.
Like Earth, Mars does possess a metallic iron core, though unlike Earth, Mars' core is not molten liquid and thus no natural magnetic field is generated around the planet. This is because of Mars' smaller size compared to Earth, which is large enough to retain the heat necessary to maintain a molten interior. Beyond the core of the planet, Mars' mantle is primarily made up of silicate and is responsible for much of the planet's volcanism and other geologic features on the planet. Finally, Mars' mantle is made up of iron, silicon, oxygen, magnesium, and calcium. The crust averages about 125km thick, while Earth's crust averages only 40km thick, again a consequence of its cooled interior.
Surface Geology & Geography
On its surface, Mars is a terrestrial planet that consists of minerals containing silicon and oxygen, metals, and other elements that typically make up rock. The surface of Mars is primarily composed of tholeiitic basalt, although parts are more silica-rich than typical basalt and may be similar to andesitic rocks on Earth or silica glass. Regions of low albedo suggest concentrations of plagioclase feldspar, with northern low albedo regions displaying higher than normal concentrations of sheet silicates and high-silicon glass. Parts of the southern highlands include detectable amounts of high-calcium pyroxenes. Localized concentrations of hematite and olivine have been found. Much of the surface is deeply covered by finely grained iron oxide dust.
As previously stated, Mars has no naturally-occurring global magnetic field, though the Aegis Program between 2054 and 2106 has resulted in an artificial magnetic field of thousands of small but powerful magnets placed in orbit of Mars. It is commonly believed that along with the rest of the planets in the Sol System that Mars formed via accretion early in the system's formation, roughly 4.6-4.5 billion years ago.
In terms of geographic features, Mars is home to over 15,000 named geographic features, with this number expecting to grow as more unnamed features are visited by humans for the first time. Some of the most prominent features on Mars include Olympus Mons, the largest mountain in the Solar System, and Valles Marineris, the largest canyon in the Solar System. Recently created or future features include the Borealis Ocean, the planned body of water on Mars that is currently in its infancy but is expected to fill up most of Mars' northern hemisphere, Elysium Insulam, the largest island on Mars expected to be formed around Elysium Montes, and the Hellas Sea, which occupies the former Hellas Basin in the southern hemisphere.
Early in its history, Mars had a large ocean in its northern hemisphere. This was approximately 4.1 to 2 billion years ago when Mars still had a thicker atmosphere and a global magnetic field due to a hotter iron core. As the planet cooled down, the core froze and the magnetic field ceased, which let solar winds blow away its atmosphere. Most of Mars' surface water subsequently evaporated away or froze into the ice caps on the planet's poles. The discovery of underground water deposits in 2013 and the discovery of flowing groundwater near the Martian equator in the summer of 2015 reinvigorated ideas that Mars still had some water left, possibly for use by human explorers. The Ares 3 mission in 2022 discovered large amounts of liquid saline water at Mars' northern ice cap.
With the start of Martian terraforming in 2052, some of the water both trapped in the surface and at the ice caps have begun to melt and remain as liquids on the surface of the planet naturally. Large orbital solar mirrors were able to melt thousands of pounds of ice per year, and in 2066 the first lakes were confirmed in Hellas Planitia, which was soon to become the Hellas Sea. In 2072, the first significant bodies of water began to form in Mars' northern lowlands, forming the foundation for the revival of the Borealis Sea, which continues to grow.
Like the oceans, Mars' atmosphere used to be much thicker, estimated to be roughly 0.965 atm approximately 3.77 billion years ago, roughly at the same time as the height of Mars' oceans. During this time, it is suspected that Mars' early atmosphere may have had much more oxygen than what was originally, with estimates going as higher as 55-60% O2 in the air, along with CO2 and Nitrogen. As mentioned previously, the cooling of the planet and the dissolution of Mars' natural magnetic field causes solar wind to sweep away Mars' atmosphere and reduce it to the extremely thin atmosphere seen pre-terraforming without human intervention.
With the start of terraforming, the thickening of Mars' atmosphere is obviously one of the main priorities for colonization and terraformation. The first few terraforming programs used carbon dioxide recycling systems to turn Mars' CO2 heavy atmosphere into O2. During the 2070s and 2080s, genetically modified algae and bacteria based on cyanobacteria were introduced to the Martian environment to further convert CO2 to O2. Starting in 2073, the Aphrodite Program is using harvested CO2 from Venus to add more carbon dioxide to the Martian atmosphere and thicken it, which will subsequently be turned into breathable oxygen.
Initial Discovery and Observations
Mars is one of the five planets visible to the naked eye, so its possible that Mars has been known to mankind since the development of humans as an intelligent species. The first recorded observations of Mars go back to the 2nd millennium Egypt, where Mars is depicted on the ceilings of tombs. Other early observations of Mars are recorded from the Neo-Babylonian Empire, the Zhou Dynasty, and Ancient Greece. It was during this time that Mars was associated with the Greek god of war, aggression, and destruction Ares, who was later adapted as the Roman God Mars, giving the planet its modern-day name.
More in-depth observations of Mars were conducted during the Renaissance. Astronomers like Nicolaus Copernicus, Johannes Kepler, and Tycho Brahe were all known to regularly observe Mars and use it as part of greater astronomical experiments and observations of other planets, primarily Venus and Jupiter. It wouldn't be until 1877 and astronomer Asaph Hall that the two moons of Mars, Phobos and Deimos, were observed, owing to their small size and proximity to the much brighter Mars.
Other notable astronomers to observe and make discoveries with Mars include Daniello Bartoli, who discovered the dark, basalt-rich regions of Mars, along with Mars' ice caps, and Giovanni Schiaparelli, who created the first geographic map of Mars in 1877. Until further research proved Mars to be uninhabitable, Mars was commonly speculated to be home to some kind of civilization, assisted by Schiaparelli describing "canali" on Mars that was meant to be described as channels, but was instead translated into "canals", embedding the idea of intelligent Martians into the popular consciousness. One of the most famous examples of this is the 1897 book The War of the Worlds by H.G. Wells, describing a fictional invasion of Great Britain by Martians seeking to colonize Earth.
During the Space Race, an ideological competition between the United States and the Soviet Union, Mars was a prime target for exploration. In 1965, the American probe Mariner-4 became the first spacecraft to successfully flyby Mars and send back scientific data. The probe revealed Mars to be a desert world with little sign of life, the opposite of what the top scientific minds of the day believed to be a possibility. Five years later, the Mariner-8 probe became the first spacecraft to orbit Mars, entering a highly-eccentric tundra orbit in November 1970. An array of Martian orbital probes from both the United States and Soviet Union were sent to Mars for the duration of the Space Race.
The first successful lander on Mars was Viking-1, landing in Chryse Planitia in 1974. Following this, 4 more Viking probes & landers were launched in 1976 and 1978. More orbiters also followed in the 1970s, 1980s, and 1990s. The Pathfinder probe in 1996 brought along with it Sojourner, the first rover on another planet. Between 1996 and 2018, more robotic probes and multiple firsts would be sent to Mars. Some of the most important missions include the Intrepid rover in 2012 (which tested basic terraforming procedures on a small scale, as well as look for water and signs of life), the Aeolus helicopter in 2016 (the first flying probe sent to another planet), and MSR in 2018 (Mars Sample Return, the first surface return from another planet).
Plans for the first manned mission to Mars began after the Houston Conference in 2010. The meeting between top administration and science personnel of NASA, the ESA, Roscosmos, JAXA, and multiple private companies set the goal for a manned mission to Mars by 2020. Immediately after the Houston Conference, architecture was put into place to begin construction on the line of vessels that would transport the first supplies and eventually people to Mars.
The Ares Program would begin with the launch of the first supplies for a manned surface base in March of 2016 when two Artemis GSTs (General Space Transporters) lifted off from Kennedy Space Center and Cayenne Space Center carrying the supplies for the first temporary base on Mars, arriving and dispensing supplies onto the Martian surface in October of 2016. On March 30th, 2018 the Ares-1 mission launched carrying 6 astronauts to Mars, landing just north of Candor Chasma on September 21st. The Ares-1 mission stayed on the Mars' surface for 570 days and lifted off on April 13th, 2020. The Ares-1 mission was followed by 9 more missions, with most landing at the Candor Chasma base and doing suborbital hops or rover missions to other sites on Mars.
The Ares 4 and 5 missions also became the first to land humans on Phobos and Deimos in 2024 and 2026, respectively, with the intention of creating bases to act as staging posts for future Mars landings. The Ares 2-8 missions were all relatively similar in duration and focus, although varying discoveries were made on each mission. The Ares 3 mission confirmed large sources of liquid water at Mars' poles, and the Ares 5 mission returned the first Martian rock and soil samples to Earth, as well as the first samples from Deimos. Ares 8, landing at Arsia Mons in 2033, began the first steps to establish Tharsistown, the first permanent base on Mars. Ares 9 and Ares 10 supplemented the creation of Tharsistown by bringing prefabricated structures, robotic helpers, and colonists. Tharsistown remained in operation from 2033 to 2087 when it was decommissioned and made a Planetary Heritage Site.
Terraforming & Colonization
Main Article: Terraforming and Colonization of Mars
By far the most significant activity on Mars is the active terraformation and colonization of the planet, with the intention of altering its atmosphere, geosphere, and hydrosphere to support Earth-based life by 2400. This has involved the importation of massive amounts of gases and chemicals designed to support this operation, such as mining comets for water and engineering bacteria designed to give off massive amounts of nitrogen and oxygen to increase the atmospheric density of the planet and make it breathable.
Such activity presents not only challenges from costs and manpower, but from the planet itself. Mars has almost no naturally present sources of these resources, and the soil of Mars has large amounts of irradiation and toxic chemicals built up from years of exposure to solar radiation and the decay of its environment. Not only this, but without the Aegis Program and its artificial magnetosphere, the solar winds would undo all of the existing work and return Mars to a completely uninhabitable state within several thousand years. As such, terraformation not only requires a large initial investment of resources, energy, and time, but continuing investments to maintain the planet's new environment.
By 2030, with the Ares program in full swing and increasing global attention on Mars, there was a significant movement pushing not only for colonization, but terraformation of Mars as a second home for humanity. This was accompanied by an extensive debate not just over the logistics and costs of such a project, but the ethical and philosophical ramifications. A global "Keep Mars Red" campaign caused significant hurdles to the project gaining public support, although the RGB Foundation ("Red Mars, Green Mars, Blue Mars") soon emerged as a prominent group lobbying for the project.
The program soon went before the United Nations, as any actions for the colonization and/or terraformation of Mars would require amending the Outer Space Treaty, which all space-going nations were bound to. A compromise was eventually worked out that allowed for claims of bases and colonies on Mars, with the exception that Mars and all other non-Earth bodies in the Solar System remain demilitarized, with only a police force allowed to exist on Mars and military observation satellites above Earth. This did not address terraformation, however, and as climate change continued to accelerate on Earth, the lobbying for terraformation of Mars to create a new home for humanity should Earth be rendered uninhabitable began to gain steam.
It wouldn't be until 2050 that the issue would be solved by the creation of the Ares Concordat, a modified version of the 2020 Luna Accords. Briefly summarized, the Ares Concordat stated that Mars would remain a demilitarized planet, that any nation willing to colonize would be able to provided they followed the Concordat's guidelines, and that all colonizing nations would contribute to the terraformation project. Historians now consider this to be the "official" start of organized colonization and terraformation of Mars.
Prior to the beginning of full-scale Martian colonization, a large-scale buildup of infrastructure to facilitate the colonization was put into place, beginning with the Hippoi Areioi craft that would allow for a continuous chain of supply ships between Earth and Mars. At the same time, the Enyo Program established Laputa Base on Phobos as a staging base for planetary landings.
The early colonization of Mars was undoubtedly difficult for those involved, largely involving setting up the infrastructure and materials required for future growth of settlements. The first real permanent bases were small, tunnel-like bases buried in Martian soil to defend against solar radiation, made of prefabricated habitats shipped from Earth. As permanent bases were established and the population of Mars grew, the Aegis Project began to create what was effectively an artificial magnetosphere, reducing concerns of solar radiation to the point that new materials with improved radiation resistance no longer required being covered by soil.
In 2061, the terraformation of the planet soon kicked into high gear as genetically engineered bacteria were seeded across Mars, designed to survive the planet's harsh environments and release large amounts of nitrogen and oxygen into the atmosphere as the importation of carbon dioxide from Venus also commenced. This was done with the intention of increasing the density of Mars' atmosphere, which at the outset of colonization registered at just 1% of Earth's atmospheric density. Doing so would serve two purposes: Making the atmosphere more breathable, and increasing surface temperatures. The CO2 was supplemented with small amounts of more potent gases, such as sulfur hexafluoride (SF6) and tetrafluromethane (R-14).
The future of the terraformation program was briefly thrown into jeopardy in 2063 when excavations in Chryse Planitia uncovered solid fossil evidence of extremely simple organisms from Mars' earlier history, causing a massive global backlash for fear that there might still have been living organisms on Mars. The United Nations agreed to put a moratorium on continuing terraformation while further explorations of the planet were carried out, studying all possible environments from the peak of Olympus Mons to the deepest parts of Hellas Planitia. Eventually, all signs came back negative for the existence of Martian life, and in 2067 terraformation resumed in earnest.
After 2072, the climate of Earth was stabilized through massive human effort (though not without cost; the sea levels rose by an average of 1 meter during this time), allowing more focus on extraterrestrial affairs. From 2072 onwards a massive spike in colonial settlement on Mars commenced, leading to what could be considered the first Martian "cities" along with some of the first births on Mars, hailed as the first time a human had been born anywhere other than Earth. Indeed, from orbit the lights of Martian settlements could be more clearly seen, and the vast patches of bacterial and algal growth began to show up as green blotches on the surface.
Another major milestone was accomplished in 2083, when the average diurnal temperature began to consistently hold above 0° Celsius, continually increasing toward Earth-like temperatures as the atmosphere continued to increase in density through the action of both engineered organisms and direct human dispersing of gases. 2087 was also a milestone for the confirmed presence of transient bodies of liquid water in the Hellas Basin, after which the continued acceleration of the planet's climate not only saw the Hellas Basin continue to fill, but lakes also formed near the equatorial regions of the planet's large polar depression as the first steps of the creation of the Borealis Ocean.
In 2097, as the planet's average temperature continued to climb toward a pre-established goal of approximately 15° C, observations from both orbit and the surface spotted the first clouds made of water vapor rather than high-altitude ice particles. As of 2110, the planet's average global surface temperature is approximately 10° C, warm enough to support permanent mid-sized bodies of water with an atmospheric pressure of about 9 PSI, conditions livable enough to allow brief excursions onto the surface without protective gear other than an oxygen mask and warm clothing. This has allowed Mars to further explode in population, with plans for the first "unenclosed settlement" of Mariner City along Valles Marineris to be established in 2140.