Mars: The Red Planet That Has Captivated Humanity for Centuries

Mars has fascinated human beings for as long as we have been able to look up at the night sky. That distinctive reddish glow, visible even to the naked eye, has inspired myths, driven scientific inquiry, and now fuels one of the most ambitious chapters in the history of space exploration. As we stand on the edge of potentially sending human beings to another planet within our lifetimes, understanding Mars — its history, its science, and its future — has never felt more urgent or more exciting.

This is the story of the Red Planet: where it came from, what it is, and where it might take us.

Why Mars Glows Red

The first question most people ask is the most obvious one: why is Mars red? The answer is surprisingly down-to-earth, in a manner of speaking. The Martian surface is covered in iron oxide — rust. Over billions of years, iron minerals in the soil oxidized, coating the landscape in a fine reddish dust that gives the planet its signature color. This dust is so fine and lightweight that Martian winds carry it high into the atmosphere, tinting the sky itself in hues of orange and pink during the day.

The Romans named the planet after their god of war because of this fiery color, and cultures across the world independently associated it with blood, battle, and conflict. In Babylonian astronomy it was known as Nergal, the star of death. In ancient Egypt, it was called “Her Desher,” meaning “the red one.” That single visual characteristic — a rusty smudge of light in a sea of white stars — shaped millennia of human mythology before anyone had any idea what Mars actually was.

A World of Extremes

Mars is a world of dramatic contrasts and record-breaking geology. At first glance it might seem like a barren, unremarkable desert, but a closer look reveals a landscape of staggering proportions.

Olympus Mons, the largest volcano in the entire solar system, rises nearly 22 kilometers above the Martian surface — roughly two and a half times the height of Mount Everest. Its base spans approximately 600 kilometers, wide enough to cover the entire state of Arizona. It is so massive that if you were standing at its base, the curve of the planet would actually hide the summit from view. It is a shield volcano, built up gradually over hundreds of millions of years by lava flows, and geological evidence suggests it may have been active as recently as 25 million years ago — a blink of an eye in planetary time.

If Olympus Mons is the planet’s greatest peak, Valles Marineris is its greatest canyon. Stretching over 4,000 kilometers in length, roughly the width of the continental United States, and reaching depths of up to 7 kilometers in places, it dwarfs the Grand Canyon so completely that comparing the two almost feels absurd. The Grand Canyon could fit inside one of Valles Marineris’s tributary canyons. Scientists are still debating its origins — it may have formed through a combination of tectonic rifting, volcanic activity, and erosion — but whatever caused it, the result is one of the most spectacular geological features in the known solar system.

Mars also holds the Hellas Planitia, an enormous impact basin in the southern hemisphere stretching roughly 2,300 kilometers in diameter and plunging about 7 kilometers below the surrounding terrain. On the other end of the scale, the planet is pockmarked with thousands of craters from ancient asteroid and meteorite impacts, a geological record of the solar system’s violent early history.

The Atmosphere and Climate

Mars has an atmosphere, but it is not one that would support human life without significant technological assistance. The Martian atmosphere is composed of about 95 percent carbon dioxide, with small amounts of nitrogen and argon and trace quantities of other gases. It is also extremely thin — the atmospheric pressure at the Martian surface is less than one percent of Earth’s sea-level pressure, roughly equivalent to what you would experience at an altitude of about 35 kilometers above Earth.

This thin atmosphere has profound consequences for the planet’s climate. It cannot retain heat the way Earth’s atmosphere does, which means temperatures swing wildly. Near the equator, a summer afternoon might reach a relatively mild 20 degrees Celsius, but temperatures plunge to around minus 73 degrees Celsius at night. Near the poles, temperatures can fall as low as minus 125 degrees Celsius. These swings happen every single day and make the engineering challenge of surviving on Mars genuinely formidable.

Mars also experiences dust storms of extraordinary scale. Local storms are common and relatively modest, but periodically — roughly every few Martian years — planet-encircling dust storms engulf the entire planet for weeks or even months. These events can reduce sunlight reaching the surface to a small fraction of its normal level, posing serious challenges for solar-powered equipment. NASA’s Opportunity rover, which operated for nearly 15 years, was ultimately silenced by a global dust storm in 2018 when its solar panels were covered and it could no longer generate power.

There is no magnetic field protecting Mars from solar radiation the way Earth’s magnetic field protects us. Mars lost its global magnetic field billions of years ago, likely because the planet’s core cooled and its internal dynamo stopped generating a magnetic shield. Without it, the solar wind has been slowly stripping away the Martian atmosphere over billions of years, and the surface is exposed to ultraviolet radiation and cosmic rays at levels that would be harmful to unprotected humans.

Water on Mars: A Story Written in Stone

One of the most scientifically significant things we know about Mars is that it was not always the frozen desert it is today. Billions of years ago, Mars was a warmer, wetter world. The evidence is written across the landscape in unmistakable ways.

Ancient riverbeds, carved by flowing water, snake across the Martian surface. Enormous outflow channels suggest catastrophic floods of a scale that dwarfs anything in Earth’s history. Mineralogical surveys from orbiting spacecraft have identified clays and carbonates — minerals that only form in the presence of liquid water. The polar ice caps contain water ice mixed with carbon dioxide ice, and radar surveys have detected what appear to be subsurface liquid water reservoirs beneath the southern polar cap.

The Mars Science Laboratory rover Curiosity, which has been roving the floor of Gale Crater since 2012, has found compelling evidence that this ancient crater once held a lake for potentially millions of years. The sedimentary layers it has analyzed suggest a habitable environment — not necessarily one that harbored life, but one where the basic conditions for life as we understand it were present.

Where did all that water go? Some was lost to space as the atmosphere thinned and the protective magnetic field faded. Some is locked in permafrost beneath the surface. Some is frozen in the polar caps. The full accounting of Mars’s ancient water is still being worked out, but the evidence that it existed is no longer seriously disputed.

The Question of Life

Did Mars ever harbor life? This is arguably the most profound scientific question of our era, and we do not yet have a definitive answer.

The conditions that existed on ancient Mars — liquid water, energy sources, organic chemistry — were at minimum not hostile to microbial life. On Earth, life appeared relatively quickly once conditions became hospitable, which has led some scientists to speculate that life may be a more universal feature of habitable environments than we once assumed. If life ever arose on Mars, it almost certainly would have been microbial. And if it arose when Mars was warm and wet, some descendants might theoretically persist today in protected subsurface environments where liquid water and geothermal heat still exist.

NASA’s Perseverance rover, which landed in Jezero Crater in February 2021, was specifically designed with the search for ancient biosignatures in mind. Jezero is believed to have once been a lake fed by river delta systems, making it an ideal place to look for preserved evidence of ancient microbial life. Perseverance has been collecting and caching rock and soil samples with the eventual goal of returning them to Earth for analysis — samples that may, if all goes according to plan, arrive on Earth in the early 2030s.

Returning samples to Earth matters enormously because the instruments we can put inside a rover, no matter how sophisticated, are limited by size and weight constraints. Earth-based laboratories can bring the full power of modern analytical science to bear on these samples in ways that are simply impossible to do on Mars. If signs of ancient life exist in those rock cores, Earth’s laboratories offer the best chance of finding them.

No confirmed evidence of past or present life on Mars has been found yet. But the search has only just begun in earnest.

Missions to Mars: Decades of Exploration

Mars has been the most visited planet beyond Earth by a significant margin. The first successful flyby was NASA’s Mariner 4 in 1965, which returned the first close-up images of another planet — 22 grainy photographs that showed a cratered, moon-like surface and shattered some of the more optimistic visions people had harbored about Mars.

The Viking landers in 1976 were the first spacecraft to successfully land on Mars and function for an extended period. They conducted biology experiments designed to detect life, produced results that were ambiguous and have been debated ever since, and returned the first panoramic images from the Martian surface. For many scientists, Viking remains a landmark mission whose full scientific meaning is still being unpacked.

The modern era of Mars exploration began with Mars Pathfinder and its Sojourner rover in 1997, which demonstrated that rovers could operate on the Martian surface and captivated a global audience. The twin Mars Exploration Rovers Spirit and Opportunity, which landed in 2004, transformed expectations entirely: both rovers dramatically outlasted their planned 90-day missions, with Opportunity operating for nearly 15 years and traveling over 45 kilometers across the Martian surface.

Curiosity landed in 2012 and continues to operate today, methodically analyzing the geology of Gale Crater and steadily climbing the central mountain, Mount Sharp. Perseverance arrived in 2021 along with its companion Ingenuity, a small helicopter that became the first powered aircraft to fly on another planet. Ingenuity far exceeded its planned five-flight demonstration and went on to complete dozens of flights, fundamentally proving the viability of aerial exploration on Mars.

Orbiting above, a fleet of spacecraft from multiple nations — including NASA’s Mars Reconnaissance Orbiter, the European Space Agency’s Mars Express, and the United Arab Emirates’ Hope orbiter — continuously monitor the planet’s atmosphere, geology, and surface changes. China’s Tianwen-1 mission successfully delivered both an orbiter and a rover to Mars in 2021, making China only the second nation after the United States to successfully operate a rover on the Martian surface.

Getting Humans to Mars

For decades, sending human beings to Mars existed comfortably in the realm of science fiction and long-term planning documents. That is changing. Multiple organizations — NASA, the European Space Agency, and most visibly SpaceX — are now actively developing the hardware, technology, and mission architectures that could make human Mars missions a reality within the coming decades.

SpaceX, founded by Elon Musk with the explicit stated goal of making humanity a multi-planetary species, has been developing the Starship launch system with Mars settlement as a primary design objective. Starship is designed to be fully reusable, capable of carrying large crews and massive amounts of cargo, and refuelable in orbit — characteristics that would be essential for a viable Mars transportation system.

NASA’s approach has been more incremental, focusing first on returning humans to the Moon through the Artemis program and using that experience to develop the technologies and operational knowledge needed for eventual Mars missions. The Moon serves as a proving ground — a place to test long-duration life support systems, deep-space habitation, and planetary surface operations while remaining close enough to Earth for a relatively rapid emergency return.

The challenges of sending humans to Mars are immense. The journey itself, at current propulsion technology, would take roughly seven to nine months each way. Astronauts would be exposed to cosmic radiation throughout the journey and during their stay, increasing their cancer risk. They would experience the muscular and skeletal effects of extended microgravity during transit. On the surface, they would face radiation, extreme cold, low pressure, and a toxic atmosphere. Any mission would need to be largely self-sufficient, since communication delays between Earth and Mars range from about 3 minutes to 22 minutes each way depending on the planets’ relative positions, making real-time guidance from Earth impossible in emergencies.

And yet, human exploration of Mars offers something that robotic missions, however capable, cannot: flexibility, creativity, and the ability to recognize and respond to unexpected discoveries on the fly. A geologist walking across the Martian surface could accomplish in a single afternoon what might take a rover weeks to do. The science case for human Mars exploration is compelling, and the engineering challenges, while daunting, are not insurmountable.

Why Mars Matters

Beyond the science and the engineering, there is a deeper reason why Mars captivates us. It is the most plausible candidate in our solar system for a second home for humanity — not necessarily because it is comfortable or easy, but because it is accessible. With current and near-future technology, Mars is reachable. Its day is only slightly longer than Earth’s, at 24 hours and 37 minutes. Its axial tilt is similar to Earth’s, meaning it experiences seasons. It has water in various forms. It has carbon dioxide that could theoretically be processed for oxygen and fuel. It has resources that could be used to build, grow, and sustain a community.

None of that makes Mars easy. But it makes Mars possible.

The question of whether humanity should become a multi-planetary species carries philosophical weight that extends well beyond Mars itself. A civilization confined to a single planet is vulnerable — to asteroid impacts, to climate shifts, to any number of catastrophes that history and science tell us are not merely theoretical. The expansion of life to another world would be, in the deepest sense, a form of insurance for everything that makes human civilization worth preserving.

Mars represents something that very few things in modern life can claim to represent: genuine, uncharted frontier. The surface of Mars has never been walked by a human being. Its geology has never been explored by human hands. Its sky has never been watched by human eyes looking upward. Whatever else may be said about the difficulties and the costs and the risks, that fact alone carries a kind of weight that is hard to dismiss.

We have been looking at that reddish light in the night sky for as long as we have been human. We named it after gods and wrote myths around it and dreamed about it in ways that now feel, for the first time, like they might come true within the lifetimes of people alive today.

Mars is not just a planet. It is a destination. And the journey toward it is already underway.