For over half a century, visionaries have dreamed of sending human explorers to Mars, Earth’s intriguing planetary neighbor. From the earliest concepts proposed by rocket pioneer Wernher von Braun in the 1950s, to the sophisticated mission architectures devised by NASA and others around the turn of the 21st century, the goal of landing astronauts on the Red Planet has inspired bold ideas and detailed technical plans. While a human mission to Mars has yet to be attempted, the decades of study have yielded valuable insights into the immense challenges involved and potential solutions for overcoming them.
The allure of Mars as a destination for human explorers is clear. Of all the planets in the solar system, Mars is the most Earth-like, with a 24.6 hour day, an atmosphere, seasonal weather patterns, and recognizable surface features like mountains, valleys, and polar ice caps. For decades, telescopic observations nurtured hopes that Mars harbored advanced life forms that had built the “canals” some astronomers claimed to see etched across its surface. While robotic probes have long since dispelled such notions, they have revealed Mars to be a world with a complex geologic history, where water once flowed and conditions may have been conducive to the development of microbial life. The discovery of potential Martian fossils in meteorites found on Earth has further fueled speculation that life may have arisen on Mars, even if it did not evolve into more complex forms.
For would-be Mars explorers, the planet’s similarities to Earth are offset by its stark differences. Mars’ atmosphere is less than 1% as thick as Earth’s and composed mainly of carbon dioxide. The average surface temperature is a frigid -63°C (-82°F), though it can rise above the freezing point of water in some locations. The lack of a global magnetic field and thick atmosphere leaves the surface exposed to dangerous levels of cosmic and solar radiation. Dust storms can engulf the entire planet for months at a time. And while Mars’ gravity is only 38% that of Earth’s, it is still sufficient to make landing and launching from the surface a major challenge.
Despite these daunting obstacles, Mars holds a powerful grip on the human imagination as a potential second home for humanity. Science fiction writers have long envisioned the transformation of Mars into a more Earth-like world through terraforming. More pragmatically, space advocates see Mars as the logical next step for human expansion beyond low Earth orbit, with the potential to support permanent bases and eventually self-sustaining settlements. Political leaders periodically declare Mars as the ultimate goal of human spaceflight, though follow-through has been lacking. Ambitious private ventures like SpaceX have also set their sights on Mars as the key to making humanity a multi-planet species.
Serious planning for human expeditions to Mars is nearly as old as the Space Age itself. Within months of the launch of Sputnik 1 in 1957, engineers were already envisioning what it would take to send people to Mars and bring them back again. While the earliest plans were necessarily based on many assumptions and unknowns, they grappled with the essential challenges of a Mars mission and established a foundation for future, more detailed studies. As the Space Race between the United States and the Soviet Union gained momentum in the 1960s, landing humans on Mars became the next logical goal after reaching the Moon, spurring further studies. The post-Apollo letdown led to a lull in Mars planning, but the late 1980s and 1990s saw a resurgence of interest driven by new scientific findings, technological progress, and political opportunity. Today, while the timeline remains uncertain, most experts consider a human mission to Mars a question of “when,” not “if.”
This article traces the history of mission planning for human expeditions to Mars from the earliest concepts of the 1950s to the sophisticated architectures of the early 2000s. Drawing on a wide array of sources, it shows how the dreams of visionaries gradually evolved into increasingly refined technical studies based on improved scientific knowledge, technological capabilities, and political and economic realities. As an overview, it does not attempt to capture every mission study or delve into deep technical detail. Rather, it aims to identify the key milestones, trends, people, and ideas that have shaped thinking about human Mars exploration over the decades. In doing so, it seeks to provide useful historical context for future planners while also highlighting the enduring challenges that have thus far kept humans from making the next giant leap.
Von Braun’s Early Vision
The roots of serious planning for human expeditions to Mars can be traced back to German rocket engineer Wernher von Braun. In the late 1940s, while interned at Fort Bliss, New Mexico after World War II, von Braun wrote a novel about an ambitious voyage to Mars. Though never published, its technical appendix was later released as Das Marsprojekt (The Mars Project).
In this work, von Braun laid out a plan for a massive expedition involving ten 4,000-ton ships and 70 crew members. Assembled in Earth orbit from parts launched by huge winged ferry rockets, the flotilla of ships would depart for Mars when the two planets were favorably aligned. Upon reaching the Red Planet, a crew would descend to the surface in winged gliders and spend over a year exploring before returning to the orbiting ships for the trip back to Earth.
While many aspects of von Braun’s concept, like the enormous spacecraft and lack of precursor robotic missions, seem fanciful by today’s standards, his plan represented the first serious technical study of a human mission to Mars. It introduced key concepts like Earth orbit rendezvous and assembly, long-duration interplanetary flight, entry into the Martian atmosphere, and scientific surface exploration that would be refined in subsequent studies. Von Braun’s background was in engineering rather than planetary science, so his Mars Project made many assumptions about the Martian environment that later proved inaccurate. But he recognized the need to design the mission architecture around the unique challenges of a Mars expedition.
Von Braun continued to champion Mars as the ultimate goal of human spaceflight throughout the 1950s. Through a series of influential articles in Collier’s magazine and books like The Exploration of Mars (1956), he painted an exciting vision of winged spacecraft, nuclear propulsion, and eventual Martian settlements that inspired a generation and helped build public support for the fledgling U.S. space program. While the technical details evolved, the basic template of his Mars Project – spacecraft assembled in Earth orbit, long-duration interplanetary cruise, landing on Mars, surface exploration, ascent and return to Earth – would inform most subsequent NASA studies.
NASA Enters the Scene
The dawn of the Space Age in the late 1950s brought human Mars missions into the realm of possibility. As soon as NASA was established in 1958, researchers there began studying advanced propulsion technologies like nuclear-thermal and electric rockets that could enable interplanetary voyages.
In 1959, Congress granted funding for the first NASA-sponsored study of a piloted Mars expedition. Conducted at the Lewis Research Center in Ohio, the study examined spacecraft powered by nuclear rockets and outlined a typical Mars mission profile: The crew would depart from Earth orbit, coast to Mars, enter orbit, send a landing party to the surface for exploration, then fire rockets for the return to Earth. This template would be followed, with variations, in most NASA Mars studies over the next several decades.
The 1960s saw a proliferation of NASA Mars studies as the agency gained experience with robotic probes and human spaceflight. Key centers of activity included the Marshall Space Flight Center, which focused on launch vehicles and propulsion; the Langley Research Center, which studied spacecraft and mission designs; and the Manned Spacecraft Center (later Johnson Space Center), which concentrated on the human aspects of spaceflight. Studies ranged from conceptual mission plans to detailed analyses of specific technologies and vehicle designs.
One of the most influential early studies was EMPIRE (Early Manned Planetary-Interplanetary Roundtrip Expeditions), conducted in 1962-1963. EMPIRE examined fast “opposition-class” missions, which would take about 400-450 days, and longer “conjunction-class” missions lasting around 900-1000 days but requiring less propellant. It also introduced the concept of using the atmospheres of Mars and Earth to slow down spacecraft (aerocapture and aerobraking), reducing the need for heavy propellant loads. The EMPIRE studies provided a foundation for much of NASA’s subsequent Mars planning.
Apollo Intervenes
NASA’s early Mars ambitions were soon overshadowed by the Apollo program to land astronauts on the Moon. Initiated by President Kennedy in 1961, the lunar effort commanded the lion’s share of the agency’s attention and resources through the 1960s. Many hoped that NASA would pursue Mars as the logical post-Apollo goal, but the huge investment required and waning political support in the wake of the Moon landings derailed those plans.
Still, Mars mission studies continued at a low level within NASA. Most notable was a series of studies in the late 1960s that envisioned an ambitious program combining a lunar base and Mars landings, serviced by reusable nuclear shuttles. Led by Wernher von Braun, then director of the Marshall Space Flight Center, these studies represented perhaps the apogee of NASA’s Mars ambitions. They called for a series of expeditions in the early 1980s, each involving two ships with six-person crews. The ships would be assembled in Earth orbit using Saturn V rockets and new nuclear upper stages. Three landing missions over three launch opportunities would explore different regions of Mars, with the eventual goal of establishing a permanent base.
Von Braun’s bold vision was presented to the Space Task Group established by President Nixon in 1969 to chart a post-Apollo course for NASA. But the political tide had turned against such expensive endeavors. Nixon had little interest in another Apollo-scale space commitment, and he opted instead for the more modest space shuttle and space station programs. NASA’s plans for a post-Apollo Mars program faded away, though lower-level studies would continue.
Waxing and Waning Visions
NASA’s Mars ambitions revived in the late 1970s and early 1980s, driven by several factors. The successful Viking landings on Mars in 1976 provided a wealth of new data about the planet’s environment and possibilities for supporting life. The space shuttle began flying in 1981, offering a powerful new launch capability. And the announcement of a new space station program in 1984 raised hopes that it could serve as a jumping-off point for missions beyond Earth orbit.
In 1981, a NASA study team delivered a report outlining possible pathways for human exploration of the solar system. Known as the “Planetary Exploration Requirements Document,” it envisioned an evolutionary program beginning with expeditions to the Moon in the 1990s and leading to Mars missions as early as 2007. The Mars expeditions would use nuclear-thermal rockets and could be accomplished with four shuttle-derived heavy lift vehicle launches per mission. Each expedition would include a crew of four and would stay on the surface for 30 to 100 days.
This expansive vision proved short-lived, however. The Challenger accident in 1986 and subsequent redesign of the shuttle system pushed the space station program back and forced NASA to curtail its long-range exploration planning. The agency’s “90-Day Study” in 1989 did examine the requirements for a human Mars mission, but it was focused on technology development needs rather than a specific mission architecture.
President George H.W. Bush briefly revived interest in Mars exploration in 1989 when he announced the Space Exploration Initiative (SEI), a long-term program to send astronauts back to the Moon and on to Mars. NASA responded with a series of studies outlining possible mission architectures, but the multi-hundred-billion-dollar price tag quickly led to SEI’s demise in Congress. The failure of SEI had a chilling effect on NASA’s Mars planning for much of the 1990s.
Mars Underground
Though no longer a NASA priority, the dream of human Mars exploration stayed alive in the 1990s, kept afloat by a dedicated community of visionaries and enthusiasts. In 1981, a conference at the University of Colorado brought together many of these “Mars Underground” members to share ideas and develop an action plan. The meeting planted the seeds for the founding of the Mars Society and other advocacy groups that would emerge in the 1990s to build public support for a human mission.
One of the most detailed Mars mission concepts of this era came from Martin Marietta (now Lockheed Martin), which had been deeply involved in planning for SEI. In 1991, the company released a study known as “Mars Direct” which aimed to develop a simple, relatively low-cost approach to human Mars missions. Mars Direct called for launching an Earth Return Vehicle directly to Mars, where it would manufacture its own return propellant from the Martian atmosphere. A second launch would then send a crew out to use the ERV. The plan was later refined and incorporated into NASA’s “Design Reference Mission,” which would serve as a point of departure for many subsequent studies.
A New Century
As the 20th century gave way to the 21st, NASA continued to refine its Mars mission architectures while also supporting an increasingly capable series of robotic missions to pave the way for eventual human exploration. The space agency’s plans received a boost in 2004 when President George W. Bush unveiled the Vision for Space Exploration, which called for a return to the Moon followed by human missions to Mars and beyond.
NASA responded with the Constellation program, which included the Ares rockets and Orion spacecraft to enable lunar exploration. While the Moon was the initial focus, Mars remained the “ultimate destination” for human spaceflight. Updated Design Reference Missions in this period featured a “Mars Semi-Direct” approach, with a crew of six spending 18 months on the surface.
The Constellation program was short-lived, however. In 2009, the incoming Obama administration cancelled it as part of a shift toward partnering with commercial companies for access to low Earth orbit. NASA pivoted to the “Journey to Mars” framework, which emphasized developing key technologies and capabilities, such as solar electric propulsion and deep space habitats, to enable long-duration spaceflight.
In the 2010s, NASA’s Mars plans continued to evolve, shaped by new scientific discoveries, technological progress, and shifting political winds. The Mars 2020 Perseverance rover, launched in July 2020, is searching for signs of ancient microbial life and caching samples for eventual return to Earth. This first step in a multi-mission Mars Sample Return campaign is seen as crucial for understanding the planet’s habitability ahead of human missions.
NASA is also supporting private sector plans for human Mars exploration. SpaceX founder Elon Musk has outlined an ambitious vision for sending settlers to Mars in fleets of reusable Starship vehicles as soon as the 2020s. While many experts consider Musk’s timelines unrealistic, the rapid progress of Starship development has brought new energy and a sense of possibility to the field.
Other companies, such as Blue Origin and Lockheed Martin, are also developing concepts for crewed Mars landers and surface habitats. International partners, including the European Space Agency, China, and the United Arab Emirates, have likewise signaled their intent to join the race to put humans on Mars.
Summary
The dream of sending humans to Mars has evolved from the realm of science fiction to a serious goal of the international spaceflight community. While a crewed Mars mission is still many years away, decades of planning and robotic exploration have brought it closer than ever to reality.
From Wernher von Braun’s earliest concepts in the 1950s to modern-day plans for sustainable exploration, each generation of Mars mission designers has grappled with the immense challenges of interplanetary travel and imagined new solutions. Political and budgetary obstacles have remained formidable throughout this history, but the allure of exploring a new world has proven equally enduring.
As a new era of human spaceflight dawns, marked by the rise of commercial capabilities and renewed international interest, the groundwork laid by decades of Mars mission planning will be an invaluable resource. While the details may change, the fundamental challenges – and the age-old yearning to see humans walk on the Red Planet – remain the same. With dedication, ingenuity, and a bit of luck, perhaps the first astronauts will soon be leaving their footprints in the rusty sands of Mars.
