The Multiplanetary Species
On October 13, 2024, a tower of steel and fire stood on the coast of south Texas. SpaceX's Starship, the largest rocket ever built, lifted off for its fifth test flight. Seven minutes later, the Super Heavy booster, still trailing flames from its descent, fell back toward the launch site. Two enormous mechanical arms, which SpaceX calls chopsticks, closed around the booster and caught it in midair. For the first time in history, an orbital-class rocket booster had returned directly to its launch tower, ready to be refueled and flown again.
This moment, captured live and watched by millions, represented something more than an engineering achievement. It demonstrated that the economics of space travel could be fundamentally transformed. Rockets have traditionally been disposable: built at enormous expense, used once, and discarded. A Falcon 9 first stage costs roughly thirty million dollars. Throwing it away after each launch makes space access expensive regardless of the payload. But a rocket that lands itself, that can be inspected and relaunched within days, changes the equation entirely.
SpaceX launched one hundred and seventy times in 2025, more than the entire rest of the world combined. The company's stated goal is not merely to dominate the launch market but to make humanity a multiplanetary species. The Starship program exists to send humans to Mars and to establish a permanent presence there. What seemed like science fiction a generation ago now has a corporate structure, a launch manifest, and a regulatory approval process.
This article explores what it would mean for humans to become a multiplanetary species: the technology required, the economics involved, the political challenges, and the philosophical implications. It is not a prediction but an exploration of possibilities that are now technically conceivable, even if their realization remains uncertain.
The Gravity Problem
To understand why space travel has remained so expensive for so long, you must understand the tyranny of the rocket equation. Every kilogram of payload that reaches orbit requires many kilograms of fuel to lift it. But that fuel itself has mass, which requires more fuel to lift. The relationship is exponential, not linear. Small increases in payload require large increases in total rocket mass.
Earth's gravity is particularly unforgiving. Escaping Earth's gravitational pull requires reaching a velocity of roughly eleven kilometers per second. The energy required to accelerate any object to this speed is enormous. Most of a rocket's mass at launch is fuel; the payload is typically only a few percent of the total.
For sixty years, humanity accepted this constraint and designed around it. Rockets were built to be as light as possible, which meant using expensive materials and accepting that they would be used only once. Payload capacities were limited, which meant that anything sent to space had to be miniaturized and optimized. The cost per kilogram to orbit remained stubbornly high, typically between two thousand and twenty thousand dollars depending on the rocket.
Reusability changes this calculus. If a rocket can be used multiple times, the manufacturing cost is amortized across many flights. SpaceX's Falcon 9 first stages have flown as many as twenty-three times each. The cost per launch has fallen accordingly. SpaceX charges roughly sixty-seven million dollars for a Falcon 9 launch, less than half what competitors charge for comparable capacity.
Starship takes reusability further. Both stages are designed to return and land. The Super Heavy booster catches itself at the launch tower. The Starship upper stage, after delivering its payload, reenters the atmosphere and lands vertically. If both stages can be reused rapidly, the cost per launch could fall to a few million dollars, and the cost per kilogram to orbit could drop below one hundred dollars.
At one hundred dollars per kilogram, space becomes accessible in ways it has never been. Launching a person to orbit would cost roughly ten thousand dollars in propellant and operations, comparable to an international airline ticket. Launching the mass equivalent of a small house would cost a few hundred thousand dollars. The economics that have constrained space development for decades would no longer apply.
The Starship Architecture
Starship is not merely a larger rocket. It represents a different philosophy of space vehicle design.
Traditional rockets are built from exotic materials: aluminum-lithium alloys, carbon fiber composites, titanium. These materials offer the best strength-to-weight ratios but are expensive and difficult to work with. Starship is built from stainless steel, a common industrial material. Steel is heavier than aluminum, but it is also cheaper, easier to weld, and more tolerant of the extreme temperatures encountered during atmospheric reentry. SpaceX concluded that the savings in manufacturing cost outweighed the penalty in performance.
The vehicle is enormous. Fully stacked, Starship stands one hundred and twenty-one meters tall, taller than the Statue of Liberty including its pedestal. It is nine meters in diameter, large enough to contain an entire Apollo spacecraft within its payload bay. The Super Heavy booster generates seventy-four meganewtons of thrust from thirty-three Raptor engines, more than twice the thrust of the Saturn V that carried astronauts to the Moon.
The propellant choice is significant. Starship burns liquid methane and liquid oxygen. Previous rockets have used kerosene or hydrogen as fuel. Methane was chosen because it can be synthesized on Mars. The Martian atmosphere is ninety-five percent carbon dioxide. Subsurface ice provides water. With energy from solar panels or nuclear reactors, these raw materials can be combined to produce methane and oxygen through a process called the Sabatier reaction. A Starship that lands on Mars could, in principle, refuel itself for the return journey without carrying fuel from Earth.
This is not a theoretical capability but a design requirement. SpaceX's architecture for Mars missions assumes that propellant will be manufactured on Mars. Without in-situ resource utilization, the mass required to send humans to Mars and return them would be prohibitive. With it, Mars missions become logistically similar to Antarctic expeditions: difficult and dangerous, but not requiring the entire industrial output of a nation.
The Lunar Stepping Stone
Before Mars, the Moon. NASA's Artemis program aims to return humans to the lunar surface for the first time since 1972. SpaceX has contracts to provide the Human Landing System, a modified Starship that will carry astronauts from lunar orbit to the surface and back.
The current timeline, as of late 2025, schedules Artemis II for early 2026. This mission will send four astronauts around the Moon without landing, the first crewed flight beyond low Earth orbit in over fifty years. Artemis III, the first crewed landing, is targeted for mid-2027, though delays are possible given the complexity of the mission and the development status of the landing system.
The Artemis architecture differs from Apollo in important ways. Apollo was a flags-and-footprints program: astronauts landed, explored briefly, and returned. Artemis is designed to establish sustained presence. The Lunar Gateway, a small space station in lunar orbit, will serve as a staging point for surface missions. Surface habitats will allow longer stays. The goal is not merely to visit the Moon but to learn how to live and work there.
The Moon is valuable as a proving ground for technologies needed on Mars. Life support systems, surface operations, in-situ resource utilization, and long-duration habitation can all be tested at the Moon, which is only three days from Earth. If something goes wrong, rescue is possible. On Mars, where the journey takes six to nine months and launch windows occur only every twenty-six months, there is no rescue option. Technologies must be proven reliable before they are trusted with human lives on Mars.
The Moon may also have economic value in its own right. Water ice exists in permanently shadowed craters near the lunar poles. This ice can be split into hydrogen and oxygen, which are rocket propellants. A lunar base that produces propellant could refuel spacecraft headed to Mars or the outer solar system, dramatically reducing the mass that must be launched from Earth. The economics of this proposition depend on the cost of lunar operations versus the cost of launching propellant from Earth, a calculation that changes as launch costs fall.
The Mars Transit
Getting to Mars is harder than getting to the Moon. The distance varies as the two planets orbit the Sun, ranging from about fifty-five million kilometers at closest approach to over four hundred million kilometers when they are on opposite sides of the Sun. Even at the speed of light, communications take between three and twenty-two minutes each way. Spacecraft cannot follow straight lines but must follow curved trajectories that minimize fuel consumption, extending transit times to six to nine months depending on the trajectory chosen.
The timing of launches is constrained by orbital mechanics. Efficient transfers to Mars are possible only when Earth and Mars are properly aligned, which occurs roughly every twenty-six months. Miss a launch window and you wait over two years for the next one. This cadence shapes everything about Mars mission planning. Supplies must be prepositioned. Return windows must be calculated years in advance. The rhythm of interplanetary travel is fundamentally different from anything in human experience.
The journey itself poses challenges that lunar missions do not. Astronauts would spend months in microgravity, which causes bone loss, muscle atrophy, and fluid shifts that affect vision and cognition. Radiation exposure during transit is significant; solar flares can deliver dangerous doses within hours. Psychological stress from confinement, isolation, and distance from Earth is difficult to predict but likely severe. The longest continuous human spaceflight to date is about fourteen months aboard the International Space Station. Mars transit would not be longer, but the impossibility of return during the journey changes its character.
Radiation is perhaps the most difficult problem. Earth's magnetic field shields the surface from most cosmic radiation. In deep space, there is no such protection. Heavy shielding adds mass, which is expensive to launch. Active shielding using magnetic fields is theoretically possible but has not been demonstrated at the scales required. The current approach is to accept elevated cancer risk for astronauts, who would be volunteers understanding the dangers. This is ethically complex but may be the only practical option for early missions.
Landing and Living
Mars has an atmosphere, unlike the Moon, but it is thin, less than one percent of Earth's surface pressure. This creates a unique challenge for landing. The atmosphere is thick enough to generate significant heating during entry but too thin to slow a spacecraft sufficiently for landing. Parachutes work poorly. Rockets must fire for extended periods to brake the final descent.
Starship's approach uses the atmosphere for initial braking, then transitions to rocket-powered descent. The vehicle enters the atmosphere belly-first, using its large surface area to generate drag. Heat shields protect against the plasma that forms around the vehicle at hypersonic speeds. Near the surface, the vehicle flips to vertical and fires its engines for the final landing. This maneuver, which SpaceX calls the belly flop, has been demonstrated in Earth atmosphere but not yet on Mars.
Once on the surface, survival depends on local resources. The Martian atmosphere provides carbon and oxygen for producing methane fuel. Subsurface ice provides water. Martian soil, called regolith, contains iron oxides that could theoretically be processed into construction materials. But none of these processes have been demonstrated at scale on Mars. The first missions would carry everything needed for survival and would test resource extraction technologies for future use.
Habitation on Mars requires protection from radiation, temperature extremes, and the near-vacuum atmosphere. Surface temperatures average around minus sixty degrees Celsius and can drop below minus one hundred degrees at night. Habitats must be pressurized and heated continuously. Airlocks must function reliably in an environment where a failure means death within minutes. Life support systems must recycle air and water with minimal losses. All of this must function for years without resupply from Earth.
The Colony Question
A base is not a colony. Antarctic research stations have operated continuously for decades, but they depend on regular resupply from the outside world. No one is born in Antarctica; no one lives their entire life there. A true colony would be self-sustaining, capable of continuing indefinitely without support from Earth.
The requirements for self-sustainability are daunting. A colony must produce its own food, which requires either hydroponics or the ability to modify Martian soil for agriculture. It must manufacture its own equipment, which requires mining, refining, and fabrication capabilities. It must maintain its own population, which requires either continuous immigration or reproduction on Mars. The minimum viable population for genetic diversity is estimated at somewhere between five hundred and fifty thousand people, depending on assumptions about genetic management.
Elon Musk has spoken of a million-person city on Mars by 2050. This would require launching roughly a hundred thousand people per year for a decade, along with vastly more cargo to support them. At Starship's projected costs and capacities, this might be economically conceivable, but it would represent an industrial mobilization comparable to wartime production. Whether such mobilization would occur without some compelling reason, some crisis that makes Mars settlement urgent, is doubtful.
The intermediate stages matter more for the near term. A base that can produce its own propellant is less dependent on Earth than one that cannot. A base that can grow some of its own food requires less cargo from Earth. Each step toward self-sufficiency reduces the cost and risk of maintaining the settlement. Full self-sustainability may take a century or more to achieve, but partial self-sufficiency is a reasonable goal for the first decades.
The Political Economy
Space exploration has always been political. The Apollo program was driven by Cold War competition with the Soviet Union. The International Space Station was designed partly to employ Russian engineers who might otherwise have worked on weapons programs. Artemis includes international partners whose participation serves diplomatic as well as technical purposes.
Mars introduces new political complexities. The Outer Space Treaty of 1967 declares that celestial bodies cannot be claimed as national territory. But it says little about resource extraction or permanent settlement. If a private company establishes a base on Mars, under whose laws do the inhabitants live? If they produce resources, who owns them? If they declare independence, what authority would stop them?
The Artemis Accords, signed by over forty countries, attempt to establish norms for lunar activity. They affirm that resource extraction is permitted and that safety zones around installations should be respected. But China and Russia have not signed. A future in which American and Chinese bases operate on the Moon or Mars under different legal frameworks is plausible and potentially unstable.
Corporate interests add another dimension. SpaceX is a private company, currently valued at over two hundred billion dollars. Its Mars program is funded partly by commercial activities like Starlink satellite deployment, but ultimately depends on Elon Musk's priorities. If Musk loses interest, dies, or loses control of the company, the Mars program could be redirected or cancelled. Governments have longer time horizons than individuals, but they also have shorter attention spans; programs that span decades require sustained political support that is difficult to maintain.
The Case for Settlement
Why go to Mars at all? The question has no single answer, and different people weight the possible answers differently.
The survival argument holds that a single-planet species is vulnerable to extinction from catastrophic events: asteroid impacts, supervolcanic eruptions, engineered pandemics, nuclear war. These events are individually unlikely in any given century but become near-certainties over geological time. A self-sustaining settlement on another planet would ensure that human civilization survives even if Earth becomes uninhabitable. The argument is not that Mars is pleasant or easy but that it is possible, and possibility is enough when extinction is the alternative.
Critics note that the resources devoted to Mars settlement could address terrestrial problems that threaten more immediate harm. Climate change, pandemic preparedness, and nuclear security all require investment. Spending billions on Mars while people suffer on Earth raises ethical questions about priorities. The counterargument is that Mars settlement need not come at the expense of terrestrial investment; SpaceX's funding comes primarily from commercial activities, not government programs that would otherwise address social needs.
The exploration argument holds that humans are curious by nature and that extending our presence to new worlds is a continuation of the explorations that have shaped our history. From the first migrations out of Africa to the voyages of discovery to the polar expeditions, humans have always pushed into new territories. Mars is the next frontier. This argument appeals to those who find value in exploration itself, independent of practical returns.
The economic argument holds that space resources will eventually be valuable enough to justify the cost of accessing them. Mars itself may not be resource-rich in ways that matter to Earth's economy, but the infrastructure developed to reach Mars could enable asteroid mining, orbital manufacturing, and other activities with clear economic value. This argument is speculative; no space resource extraction has yet proven profitable. But the same was true of many historical frontiers before their development.
The Human Element
Discussions of Mars settlement often focus on technology and economics while neglecting the human experience. What would it be like to live on Mars?
The first settlers would be volunteers, probably selected from populations of astronauts, scientists, and engineers. They would know the risks and accept them. But they would also experience isolation unlike anything in human history. Communication delays make real-time conversation with Earth impossible. The landscape is barren: red rocks under a butterscotch sky, no plants, no animals, no other people except those who came with you. The psychological effects of such isolation are unknown because no one has experienced them.
For the first generation, Mars would be a destination chosen by adults who knew what they were getting into. But what about their children? A person born on Mars would grow up in lower gravity, breathing recycled air, never experiencing rain or forests or oceans. They might never visit Earth; the transition from Mars gravity to Earth gravity could be physiologically difficult for someone who had never experienced it. These hypothetical Martians would be human, but their experience of being human would differ profoundly from anything we know.
The ethical implications are significant. Bringing a child into existence on Mars means imposing a life of constraints they did not choose. Some would argue this is no different from bringing children into any constrained circumstance; every child is born into conditions they did not select. Others would argue that knowingly creating humans for an existence so limited raises special concerns. These questions do not have easy answers, and they will become urgent only if settlement proceeds to the point where reproduction is possible.
The Timeline
Predictions about space development have a poor track record. In 1969, it seemed plausible that humans would reach Mars by the 1980s. Instead, we have not traveled beyond low Earth orbit since 1972. Technological capability is not the only constraint; political will and economic incentives matter more.
The current trajectory suggests several milestones. Starship will likely achieve regular orbital flights within the next few years. The Artemis program will return humans to the Moon in the late 2020s if schedules hold. An uncrewed Starship could land on Mars by the early 2030s, demonstrating the entry, descent, and landing technologies. Crewed missions could follow later in the 2030s if the uncrewed tests succeed and if funding and political support continue.
A self-sustaining colony is a more distant prospect. Even optimistic projections place it decades away. The history of frontier development suggests that early settlements depend on their sponsors for a long time before achieving independence. Mars would be no different, and probably slower given the technical challenges.
What seems likely is that some humans will reach Mars within the lifetimes of people alive today. Whether they establish a permanent presence depends on factors that cannot be predicted: technological breakthroughs, economic conditions, geopolitical events, individual decisions by key actors. The path from first landing to true settlement is long and uncertain. But the first steps on that path are being taken now.
The Present Moment
In 2025, SpaceX launched more rockets than any organization in history. The company caught a rocket booster with mechanical arms and is iterating rapidly toward fully reusable orbital flight. NASA is preparing to send astronauts around the Moon for the first time in over fifty years. China is developing its own heavy-lift rockets and has announced plans for crewed lunar missions by 2030.
None of this guarantees that humans will become a multiplanetary species. Technical challenges remain unsolved. Political and economic support could evaporate. The whole enterprise could prove impractical or undesirable once attempted. History is full of frontiers that were opened and then abandoned.
But the possibility is real in a way it has not been before. The technology exists or is being developed. The economics are becoming favorable. The will to try exists in at least some organizations and individuals. Whether humanity becomes multiplanetary depends on choices that have not yet been made, but the option to make those choices is now available.
The rockets that will carry the first humans to Mars may already be under construction. The people who will make that journey may already be alive. What was once science fiction is becoming engineering, and what was once speculation is becoming planning. The multiplanetary future is not certain, but it is no longer impossible. That shift, from impossible to uncertain, is the story of 2025.