Jeff Bezos vs. Elon Musk: Who Wins the Space Race—Mars Cities or Giant Orbital Megastructures by 2045?

Bezos’ bet: Jeff Bezos has been publicly advocating O’Neill–style orbital habitats—spinning, city‑scale space settlements built in Earth’s neighborhood—arguing that “millions” of people could live off‑world within decades. His most recent high‑profile comments came at Italian Tech Week (Turin) in September 2025. Financial Times
Musk’s bet: Elon Musk’s plan centers on settling Mars via SpaceX’s fully reusable Starship, with uncrewed Mars shots as early as 2026 and an eventual self‑sustaining city within ~20 years if development goes well. Reuters
The blueprint for orbital living exists: NASA’s 1970s Space Settlements: A Design Study and Gerard O’Neill’s The High Frontier laid out rotating habitats (cylinders, tori) with artificial gravity and in‑space industry, concepts Bezos explicitly embraces. NASA Technical Reports Server
Bezos’ near‑term hardware: Blue Origin’s New Glenn reached orbit for the first time in January 2025; the company co‑leads Orbital Reef, a NASA‑funded commercial space‑station effort advancing inflatable habitat tech. Reuters
Musk’s near‑term hardware: SpaceX’s Starship completed a milestone 10th test flight in August 2025, including mock satellite deployment and improved reentry performance—steps toward deep‑space missions. Reuters
Critical hurdles: Long‑duration human health risks (radiation, bone loss), orbital debris, and space law (property/sovereignty under the Outer Space Treaty) stand in the way of “millions in space” within 20 years. UNOOSA

The story: Two billionaires, two roadmaps for humanity’s off‑world future

When Jeff Bezos and Elon Musk talk about colonizing space, they’re not arguing over tactics—they’re debating different destinations and architectures for civilization itself. Musk’s path is planetary: build a Mars city with Starship. Bezos’s is cislunar and orbital: erect giant, rotating habitats in Earth’s vicinity, supplied by a new, largely space‑based industrial economy. At Italian Tech Week in 2025, Bezos again sketched this vision—millions of people living in space within decades—reviving a 1970s idea that he says fits physics, economics, and the long‑term health of Earth. Financial Times

Bezos’s case: O’Neill cylinders, orbital cities, and moving industry off Earth

Bezos openly favors orbital megastructures over planetary colonies, citing Princeton physicist Gerard K. O’Neill’s argument that planets are “too small” and limiting for mass human settlement. In this model, habitats spin to provide artificial gravity, feature controlled climates, and are built from lunar/asteroid materials to minimize launches from Earth. He has repeatedly framed the goal as “millions of people living and working in space” and ultimately moving heavy/polluting industry off Earth so our planet can be preserved. Ars Technica

The intellectual scaffolding is classic NASA/O’Neill. The 1975–77 NASA Ames summer studies and O’Neill’s The High Frontier detail how large free‑space habitats could use lunar regolith and in‑space manufacturing, with rotation delivering Earth‑like gravity. These are the concepts Blue Origin’s founder regularly cites as the end state his company wants to enable. NASA Technical Reports Server

Steps on the road: In January 2025, Blue Origin’s heavy‑lift New Glenn finally reached orbit—a prerequisite for hauling the mass needed for stations and in‑space infrastructure. In parallel, Blue Origin and Sierra Space’s Orbital Reef station progressed through NASA‑backed burst‑pressure tests of Sierra Space’s inflatable LIFE habitat shell, a tangible milestone toward larger pressurized volumes in orbit. Reuters

Musk’s case: A city on Mars, enabled by Starship

Elon Musk argues that becoming multiplanetary is necessary to safeguard civilization and that Mars is the best next home. He has floated timelines for uncrewed Mars landings as early as 2026–2028, with crewed missions thereafter, eventually ramping toward a self‑sustaining city within ~20 years—an aspiration he has repeated alongside a longer‑term ambition for a million residents by mid‑century. Reuters

That hinges on SpaceX’s Starship. After a bruising development phase, Starship’s tenth flight in August 2025 achieved key test objectives (including satellite deployment demonstrations)—incremental, but important, progress toward the capabilities a Mars campaign would require. Reuters

What the experts say about feasibility

Historical and technical grounding (pro‑orbitals): O’Neill’s NASA‑linked design studies argue free‑space habitats can scale, avoid deep planetary gravity wells, and tailor gravity via rotation. Recent work by Al Globus and collaborators suggests equatorial low Earth orbit (ELEO) locations have sufficiently low radiation to reduce shielding mass for early settlements, potentially making incremental growth from small stations more achievable. NASA Technical Reports Server
Resources & in‑space economics: Planetary scientist Philip Metzger has modeled how lunar‑derived propellant and in‑space resource use could gain comparative advantage over Earth‑launched fuel as traffic grows—an economic lever for Bezos‑style cislunar industry. arXiv
Mars advocacy (pro‑planets): Robert Zubrin, founder of the Mars Society, argues Mars uniquely offers the elements and energy for a technological civilization, aligning with Musk’s planetary vision (though Zubrin’s focus is a stepwise path via affordable launch, ISRU, and robust logistics). NSS
Human health constraints (skeptical of near‑term mass settlement): NASA’s Human Research Program continues to document risks to bone, muscle, cardiovascular and cognitive health from long‑duration spaceflight and space radiation, underscoring the need for countermeasures and shielding—on Mars and in orbit. Recent HRP evidence reports and program summaries highlight elevated fracture risk after long missions and the need to cap career radiation exposure. NASA Technical Reports Server
Cultural/legal skepticism: Science‑policy voices—including the authors of A City on Mars—contend that timelines for large‑scale settlement are wildly optimistic, and that unresolved governance and property‑rights questions could be showstoppers. The Outer Space Treaty bars national sovereignty claims in space, creating uncertainty about land/asset rights for would‑be settlers and investors. Space
Orbital environment risks: The ESA Space Environment Report (2025) warns that orbital debris is growing unsustainably, complicating any vision of densely populated orbital neighborhoods unless deorbit rules (like the U.S. FCC’s 5‑year disposal requirement) and active mitigation scale up quickly. European Space Agency

What the next 5–10 years will decide

Stations to replace the ISS: NASA intends to retire the International Space Station around 2030, with a U.S. Deorbit Vehicle under development (award in 2024). The plan is to transition to commercial LEO destinations—including concepts like Orbital Reef—which, if they materialize on schedule, are the bridge from today’s crews of seven to tomorrow’s larger orbital populations. NASA
Inflatable habitats & industrial modules: Continued burst tests, life‑support demonstrations, and on‑orbit pathfinders for inflatable/expandable modules are crucial. Success here enables much larger volumes per launch—a must for orbital settlement scaling. NASA
Heavy‑lift cadence: New Glenn now exists; the question is reliability and flight rate. High‑cadence, partially reusable heavy lift—by Blue Origin (New Glenn) and SpaceX (Starship)—is what makes large habitat logistics and Mars cargo campaigns financially plausible. Reuters
Lunar infrastructure: Blue Origin’s Blue Moon lander (selected in 2023 for Artemis V) embodies the cislunar build‑out Bezos says we need—fuel depots, tugs, and surface operations to turn the Moon into a materials and propellant node for orbital construction. NASA

So…millions living in space by 2045?

Short answer: It’s a stretch.

Bezos does say “millions” will one day live off‑world and has recently suggested it could happen “within decades,” but he has not published a concrete, resourced plan that gets to millions by the mid‑2040s. His companies are, however, ticking off enabling milestones (New Glenn to orbit; Orbital Reef habitat tests), which are necessary but far from sufficient. Financial Times
Musk’s timeline for Mars—uncrewed by 2026–2028, crewed a few years later, then scaling—is aggressive and subject to Starship’s maturation, planetary‑protection policy, and life‑support readiness for months‑long transits and surface operations. The 10th flight progress is real, but it’s still early in proving the full, rapid‑reuse system Starship requires. Reuters
Independent experts point to health, legal, and environmental barriers to near‑term mass settlement—orbital or planetary. Radiation and skeletal risks remain substantial for long durations; debris complicates LEO expansion; and the Outer Space Treaty leaves sovereignty and property questions unresolved, chilling private investment at settlement scales. NASA

Bottom line: By 2045, a realistic win may be hundreds to a few thousand people living and working off Earth across multiple commercial stations and lunar installations—not “millions.” The race between Bezos’s orbital‑first and Musk’s Mars‑first strategies is real, but both depend on launch cadence, life‑support breakthroughs, robust in‑space economies, and clear rules of the road. NASA

What would make Bezos’s orbital vision suddenly feel plausible?

Cheaper mass to orbit: If New Glenn and Starship achieve routine, high‑cadence reusability, the cost curve bends toward large orbital construction. Reuters
Cislunar logistics: Demonstrated lunar ISRU and propellant depots would slash the penalty of hauling everything up from Earth. Metzger’s work indicates lunar propellant can gain comparative advantage as traffic grows. arXiv
Habitat scalability: Repeated LIFE‑class inflatable successes and first on‑orbit, human‑rated expandable modules in commercial service. NASA
Debris discipline: Widespread adherence to the 5‑year deorbit rule and active debris removal to keep LEO usable for settlement‑scale traffic. Federal Register
Governance clarity: Updated frameworks that reconcile the Outer Space Treaty with practical property/resource rights, unlocking long‑horizon private capital. UNOOSA

And what could validate Musk’s Mars timeline?

Starship: Multiple back‑to‑back successful flights, rapid refurbishment, and orbital refueling demos—each a prerequisite for interplanetary missions. Reuters
Mars tech stack: EDL (entry‑descent‑landing) for a 100‑ton class vehicle on Mars, and credible ISRU (e.g., Sabatier methane/LOX) to close the loop. (Musk’s target windows hinge on solving these.) Reuters
Policy: Alignment with NASA and international partners—especially as the ISS retires and agencies juggle resources between LEO stations, Moon, and Mars. NASA

Sources & further reading

Bezos reiterates orbital‑habitat vision (“millions” within decades) at Italian Tech Week; context on Blue Origin and Musk’s Starship. Financial Times, Oct. 2025; FT Tech Tonic podcast. Financial Times
Bezos’s O’Neill‑inspired vision and 2019 Blue Origin talk; “move heavy industry off Earth.” Ars Technica (2019); Forbes (2023); CBS News (2021). Ars Technica
Foundations of orbital settlement: NASA’s Space Settlements: A Design Study (1977) and O’Neill’s The High Frontier. NASA Technical Reports Server
Blue Origin milestones: New Glenn’s first orbital flight (Jan 2025); Orbital Reef LIFE burst tests (2024); NASA CLD updates (2024). Reuters
SpaceX milestones & Mars timelines: Reuters coverage of uncrewed Mars targets and Starship’s 10th test (Aug 2025); Musk’s long‑term Mars population goal. Business Insider
Expert perspectives: Al Globus on nearer‑term ELEO settlements; Philip Metzger on lunar‑propellant economics; Robert Zubrin on Mars resources & settlement rationale. NSS
Constraints: NASA HRP on radiation/bone risks; ESA Space Environment Report (2025) on debris; Outer Space Treaty on non‑appropriation. UNOOSA

The takeaway

Bezos and Musk are not talking about the same future. One imagines Earth as the garden and space as the factory and metropolis (Bezos); the other imagines a new world across interplanetary space (Musk). By 2045, we are likely to see commercial LEO stations, lunar missions, and perhaps the first serious Mars sorties—remarkable progress but still shy of “millions in orbit.” The decisive factors won’t be rhetoric, but launch economics, human biology, industrial supply chains in space, debris discipline, and law. If those move faster than expected, Bezos’s orbital neighborhoods could grow surprisingly quickly; if Starship matures and Mars EDL/ISRU clicks into place, Musk’s red‑planet beachhead could arrive sooner than skeptics think. For now, both futures are still rivals—and complements—in the same race.