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Pioneering the growth of space settlements

Conceptual illustration of Station 520, a 320 meter diameter rotating orbital space settlement constructed from Stellamer, a plant-based thermoset mixed with plant fiber fillers extruded via an additive manufacturing system. Credit: Orbital Construction Pioneers

At a presentation at ISDC 2026, Orbital Construction Pioneers (OCP) introduced the First Step Manufacturing System (FSMS): an orbital additive manufacturing system that could potentially produce segments for very large structures (on the order of a few hundred meters long) using a bio-material derived from plants grown and processed in orbit.

Why is this important? Humanity’s long-term expansion into the solar system cannot be sustained by continuous resupply from Earth. The cost, complexity, and sheer mass penalties of launching every kilogram of food, water, oxygen, fuel, structures, and spare parts out of Earth’s gravity well become prohibitive as missions move farther out from low Earth orbit. In situ resource utilization (ISRU) has long been recognized as the only practical path to sustainability.

OCP has developed the FSMS as a promising architectural response to this challenge. FSMS is an orbital fabrication platform whose core innovation is biological additive manufacturing. Hydroponic and aquaponic farms operating inside a rotating space station would generate plant biomass that serves as both binder and filler for Stellamer, a bio-derived thermoset polymer. This material could enable continuous, large-scale additive manufacturing of structural components in an artificial-gravity environment. The system simultaneously produces life-support commodities and specialized mission components, creating a symbiotic industrial-ecological ecosystem.

George Tyson, CEO of OCP, came on The Space Show on July 28th to discuss the company’s plans and progress to date with David Livingston and me, along with several members of The Space Show Advisory Board. Tyson spoke with us from his lab in Colorado City, Texas, on the development of Stellamer and showed samples of the material he’s tested. When asked about the technology readiness level of flight-ready hardware and plans for orbital demonstration flights, Tyson indicated that it was still in the early research stages but as soon as they have optimized the Stellamer formulation and are satisfied with the performance of their prototype printer, the next milestone would be validation of the equipment under microgravity conditions on a parabolic flight platform.

Tyson also made an exclusive media announcement. In partnership with Hawaii-based Exo-Scientific, the companies are forming the Interplanetary Regen Network (IRN), a multi-party consortium focused on the collaborative development of bioregenerative systems, advanced in-space construction techniques, and ISRU technologies to sustain human presence beyond Earth. Exo-Scientific provides integrated solutions in engineered aquatic life systems for closed-cycle cultivation, ISRU management, and the practical application and adaptation of Earth-proven sustainability principles to offworld environments. I asked Tyson if Exo-Scientific would provide the life support systems for OCP’s space stations via their aquaponic ecosystems, but he was under an NDA at this juncture, so could not comment on the question. Exo-Scientific was also a presenter at ISDC2026 on their Coral Wetlab concept. Clearly, the company’s systems could be synergistic and complementary to OCP’s technology and plans.

The IRN is soliciting discussions with potential consortium members, government partners, research institutions, and commercial clients interested in advancing bioregenerative systems, in-space construction, and ISRU capabilities for cislunar, lunar, and Mars applications.

OCP’s long-term plan for full-scale implementation of FSMS is to start with the construction of Station 520 in medium Earth orbit (MEO), a 320-meter-diameter rotating habitat that would generate lunar-level artificial gravity at one revolution per minute. The pressurized volume would be approximately 774,000 cubic meters, sufficient to house extensive farms, processing equipment, habitation quarters, and specialized manufacturing functions such as pharmaceutical production and thin-film fabrication. A large-format 3D printer would sit at the geometric center, capable of producing structural segments up to 50 meters across and 6 meters thick. These segments would clad the station’s primary truss frame and enable the fabrication of additional modules.

OCP envisions construction beginning with the launch of seven Version 3 Starship-sized vehicles (or equivalent) that would deliver the essential components for assembly. These vehicles would contain enough scaffolding for the station skeleton, hydroponics and aquaponics materials, the necessary items for the construction of the 3D printer located at the center, plant processing equipment, food, water, air, tools, and EVA suits used by the construction crew. A repair station for EVA suit and equipment maintenance would also be provided, including a small startup crew’s quarters and work area.

Once the vehicles reach MEO, the scaffolding would be employed to build the station skeleton while incorporating the seven vehicles themselves into the emerging framework. Appropriate items such as propulsion systems, electronics, pumps, and related equipment would be relocated from the vehicles to their permanent placement on the scaffolding. The tanks and cargo areas of the vehicles would then be connected to provide pressurized sections that serve as the initial farms. With these foundational elements in place, the station could be spun up to one-third rotation, allowing the hydroponic and aquaponic systems to be mounted and activated.

As plant material becomes available, the plant processing system would be assembled and activated. This system creates the material—thermoset epoxy and plant fibers—required for use in the printer. Using a mix of the station-produced thermoset and plant material, the outside skin and inside bulkheads would then be printed. As the outside of the station is skinned, additional sections would be enclosed and pressurized to accommodate new hydroponic and aquaponic farms. When the construction of the station is complete, rotation is increased to one rpm, and tenants could then be allowed to move in.

As stated previously, central to this entire sequence is the FSMS 3D printer, which would be integrated into the structure of the station. The printer will utilize materials grown and processed on the station. Printed items up to 50 meters across and 6 meters thick will be used to sheet the truss frame of the station. Beyond these large segments, the printer is also capable of printing other shaped parts of varying size, such as I-beams, triangles, tubes, tanks, and similar components, thereby creating various pressurized modules that will increase the size and volume of the station as well as support other applications. The printer will rely exclusively on station-derived thermoset bio-binder and plant-derived fillers, both of which would be hydroponically grown and processed on the station.

Illustration of Station 520 under construction in MEO. The top is in the process of being enclosed, exposing the internal scaffolding. Credit: Orbital Construction Pioneers

Once operational, Station 520 would become a self-sustaining ecosystem. Waste streams would be fully recycled; oxygen and water continuously regenerated; methane produced from biological waste; and plant fibers would become industrial feedstock. It is believed that outputs will exceed the station’s own needs and could be traded with visiting spacecraft, providing refueling, resupply, and waste-processing services. In this way, FSMS will transform Station 520 into a renewable manufacturing hub that could produce structural mass, life-support commodities, and mission-specific modules. It could become the first practical foundation for a non-Earth-centric orbital economy and simultaneously offer the United States a strategic industrial and defense platform in orbit. It is being positioned as a gateway to the Moon and Mars.

Tyson’s vision doesn’t stop in low Earth orbit. He shared with me a draft paper that he intends to submit for consideration as a presentation at ISDC 2027, of an economic model based on FSMS that lays the foundation for a space-based economy that could extend throughout the solar system. The rest of this post is based on his insights from that paper, with his generous permission.

Progression of Orbital Economic Development

Orbital economic development will follow a predictable sequence analogous to the terrestrial progression from subsistence agriculture to industry and then to commerce. The sequence will be shaped by mass constraints, the necessity of closed-loop life support, and the requirement for continuous production. FSMS will supply the architecture that will enable an orbital station to advance through each stage without reliance on Earth-supplied resources.

The initial stage will be biological sustainability. Hydroponic and aquaponic systems will generat food, oxygen, water, and biomass, forming the ecological base required for long-duration habitation. This stage mirrors early agricultural settlements in which reliable food production enabled population growth and the beginnings of specialization.

The second stage is industrial capability. FSMS converts biological output into structural mass, life-support commodities, and manufacturing feedstock. The transition is analogous to terrestrial industrialization, in which local production of steel, concrete, and machinery enabled large-scale construction and economic expansion. In orbit, manufacturing will break the launch vehicle fairing-size constraint and permit the creation of large rotating habitats, industrial modules, and specialized stations.

The third stage is economic expansion. Once primary and secondary outputs become established, tertiary services will emerge—logistics, crew support, data services, defense infrastructure, and interstation trade. These services will create economic gravity that attracts additional stations, missions, and commercial operators. Over time, specialized stations will form clusters, and clusters will form networks, producing a resilient orbital economy capable of supporting interplanetary operations. This progression will transform Station 520 from a single manufacturing node into a central hub of orbital commerce and will lay the foundation for sustained human presence in cislunar space and eventual expansion to Mars, the asteroid belt, and beyond.

Station 520 as the First Orbital Industrial Hub

Station 520 is designed from the outset to function as an industrial hub rather than a research outpost or mere logistics waypoint. Its scale, closed-loop ecology, and manufacturing capability will allow it to operate as a self-sustaining economic engine. The ability to produce more than it consumes is intentional. Visiting spacecraft will be able to offload waste, receive processed commodities, refuel, resupply, and acquire custom-fabricated components. These exchanges will create predictable traffic patterns and establish the station as a focal point for orbital logistics. Subsequent stations will rely on Station 520 for structural modules, life-support commodities, and specialized manufacturing services. The role is analogous to that of early industrial cities that anchored regional economies by supplying essential goods and services. Station 520 will perform the same function in orbit, serving as the first node in a network of infrastructure that will eventually support interstation trade, defense operations, scientific research, and interplanetary missions.

Cluster Formation and Interstation Trade

When Station 520 begins production, it will naturally attract additional stations seeking reliable supply, fabrication services, and ecological support. Orbital clusters will form through economic gravity rather than centralized planning. Stations will appear where production, logistics, and habitation needs intersect, creating dense regions of activity similar to terrestrial industrial districts. The first cluster will form around Station 520 because it will supply the essential goods required for orbital expansion. Research stations, agricultural modules, logistics depots, defense platforms, and specialized manufacturing nodes will locate nearby to minimize transit time and maximize access to FSMS outputs. As each station specializes, interstation trade will increase, strengthening the entire cluster.

Trade flows will follow predictable patterns. Structural modules will move outward from Station 520 to new construction sites. Life-support commodities will circulate among habitation stations. Waste streams will move inward for processing and conversion into fuel, fertilizer, and industrial feedstock. Data, navigation, and timing services will flow across the cluster, supporting operations and defense. Over time, these exchanges will create a resilient economic ecosystem capable of supporting large populations and complex industrial activity. Cluster formation will mark the transition from isolated stations to interconnected economies, enabling specialization, efficiency, and scalability. As clusters grow, they will become staging points for expansion to lunar orbit, Mars transit routes, and eventually the asteroid belt.

Expansion Beyond Earth Orbit

Once an orbital cluster becomes self-sustaining, expansion beyond Earth orbit will be economically viable. The historic limiting factor for deep-space missions has been mass: every kilogram launched from Earth carries a cost penalty that compounds with distance. By producing structural mass, life-support commodities, and fuel precursors in orbit, FSMS will eliminate much of this penalty and enable missions that would otherwise be infeasible.

The first stage is cislunar expansion. Stations positioned at Earth–Moon Lagrange points or in lunar orbit will rely on Station 520 for construction modules, ecological support, and resupply. These stations will specialize in mining, scientific research, logistics, or defense. Their proximity will permit efficient trade and form the first interorbital economic corridor.

The second stage is Mars transit. Large rotating habitats fabricated in orbit will provide artificial gravity, radiation protection, and closed-loop life support for long-duration missions. Instead of launching fully assembled transit vehicles from Earth, FSMS will enable modular construction in orbit, reducing launch mass while increasing mission size and flexibility. Transit vehicles will be refueled, repaired, and upgraded at Station 520 before departure.

The third stage is the asteroid belt. Resource extraction becomes economically viable only when processing and manufacturing occur near the source. FSMS-derived technologies such as large rotating habitats, closed-loop ecology, and modular fabrication will enable industrial operations in deep space. Stations built in orbit will become templates for asteroid-based manufacturing hubs capable of producing metals, volatiles, and industrial feedstock. Expansion beyond Earth orbit will therefore be the natural consequence of establishing a functional orbital economy. Once mass can be produced in space, the solar system will become accessible in a manner that Earth-launched missions alone cannot achieve.

Strategic Implications for the United States

A functional orbital economy will be both an industrial achievement and a strategic asset. Nations that control orbital manufacturing, logistics, and closed-loop ecological systems will shape the future of space commerce, defense, and exploration. Station 520 will provide the United States with the first platform capable of sustaining large-scale orbital operations without continuous Earth resupply, establishing a durable advantage in cislunar space.

Manufacturing in orbit will break the launch-vehicle constraint that currently limits the size and capability of U.S. orbital assets. Large rotating habitats, industrial modules, and defense platforms can be built and maintained without the limitations of Earth’s gravity well. This strengthens national security by enabling resilient infrastructure that cannot be easily disrupted by terrestrial launch bottlenecks or adversary interference. Closed-loop ecological systems will provide strategic endurance: stations that produce food, water, oxygen, and fuel locally can operate indefinitely, supporting long-duration missions, rapid response, and persistent presence in critical orbital regions. They also allow the United States to support allied missions, humanitarian operations, and scientific research without overburdening terrestrial logistics. Interstation trade and cluster formation will create strategic depth. A distributed network of specialized stations will support defense, commerce, and exploration while reducing vulnerability and increasing operational flexibility. The same capabilities extend beyond Earth orbit, enabling construction of Mars transit vehicles, asteroid-belt industrial hubs, and deep-space research stations. By establishing the first functional orbital economy, the United States positions itself to lead the next era of human expansion into the solar system.

The Economic Path to a Solar-System Civilization

The emergence of an orbital economy will mark a fundamental shift in humanity’s relationship with space. For six decades, orbital activity has been constrained by Earth’s gravity well, limited launch mass, and the absence of local production. FSMS will break these constraints by enabling continuous, renewable manufacturing in orbit. With Station 520 the United States could establish the first platform capable of producing structural mass, life-support commodities, and industrial feedstock without reliance on Earth-supplied resources.

This capability will transform orbital stations from isolated outposts into interconnected economic actors. Primary outputs will create the foundation for habitation and construction. Secondary outputs will expand industrial capability and ecological resilience. Tertiary outputs will generate logistics, services, and strategic infrastructure. Together, these layers will form a scalable economic architecture capable of supporting clusters, trade networks, and deep-space missions. Once mass can be produced in orbit, expansion beyond Earth will become economically inevitable. Cislunar stations, Mars transit vehicles, and asteroid-belt industrial hubs will follow naturally from the ability to fabricate large structures and sustain crews without continuous resupply. The solar system will become accessible not primarily through larger rockets but through the emergence of a functional orbital economy.

Station 520 is the first step in this transformation. It will supply the United States with a durable industrial foothold in orbit, generate economic gravity that attracts additional stations, and lay the foundation for a solar-system civilization built on renewable orbital manufacturing. The path forward is clear: build the economy first, and the civilization will follow. Orbital Construction Pioneers is blazing the trail with FSMS.

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National Space Society announces Orbital Space Settlement Design Project

Artist’s impression of the interior of a 500m diameter cylindrical spin-gravity space settlement, whose detailed engineering design is one possible output of the NSS Orbital Space Settlement Design Project. Credits: Bryan Versteeg / Spacehabs.com

In a presentation at this year’s International Space Development Conference, which took place in McLean, Virginia, June 4th through June 7th, National Space Society (NSS) COO/SVP Dale Skran announced the kickoff of an open-source Orbital Space Settlement Design (OSSD) Project. The initiative has been under active development for over a year within the NSS Space Settlement Advocacy Committee (SSAC) and the newly forming NSS Board of Scientific and Technical Advisors (BSTA). Full disclosure: Yours truly is a member of the SSAC. It was officially approved as an NSS Project last March. The content of this post is based on Skran’s presentation, supplemented with subsequent material presented to the SSAC, with permission.

The current OSSD project Study Group core team consists of Dale Skran, Frederick (Rick) Jenet, PhD, and Bryce Meyer, with all BSTA and SSAC members actively involved in review and discussion. Work is currently focused on establishing a foundational set of design inputs in the form of “Questions” (see below). A dedicated workshop to refine these questions will be held at the NSS Space Settlement Summit taking place at the University of Central Florida, October 25th and 26th. This will be followed by a public announcement and formal request for comment from the broader community. In addition, the “OSSD Terms of Reference” (TOR) and the design input Questions will be located on a dedicated NSS website. The final recommendations will be published in the NSS Space Settlement Journal.

What are Terms of Reference?
The TOR is a formal document that defines the mandate, scope, responsibilities, boundaries, and working methods of the OSSD project. TORs are recursive — a large project such as this one can be subdivided, with each subdivision having its own TOR. This powerful technique is derived from the International Telecommunications Union (ITU) standards development process.

What is the Objective of the OSSD Project?

The core goal is to produce the first complete buildable engineering design for a rotating space settlement. The project is primarily an engineering and systems-design effort, not a policy activity, although legal and economic aspects are necessarily included because they affect feasibility.

Why Pursue This Project?

Rotating space settlements as envisioned by Gerard K. O’Neill will remain an empty dream until they become buildable realities. To many observers, it has not yet been fully established that such settlements are feasible. A fully realized engineering design will be a huge leap forward in making the case that settlements in free space lie in humanity’s future. The research and development required could also address many important issues back on Earth (e.g., closed-loop systems, resource efficiency, energy production, materials science, and robotics).

Why Should the NSS Lead This Effort?

The NSS is uniquely positioned because it is:

  • Non-partisan.
  • Not aligned with any particular company or region.
  • Interested in broadening access to space for all of humanity.
  • Possesses the necessary contacts to convene such a project.
  • Has the longevity and reputation to be taken seriously.
  • Can serve as a respected “honest broker” between different companies, products, technologies, and design approaches.
  • Operates as a non-profit.

Why Now?

Several converging factors make 2026 the right moment:

  • It is over 50 years since the landmark 1975 NASA-Ames space settlement summer study and since the founding of the L5 Society, which later merged with the National Space Institute in 1987 to form the NSS.
  • The NSS laid critical groundwork with the invitation-only Space Settlement 2021 Workshop (SSW), resulting in the book “A Dream Renewed: O’Neill’s Vision in the 21st Century,” a paperback/magazine provided to NSS members, ISDC attendees, and coming out in hardcover on August 25, 2026, available for pre-order.
  • Sufficient knowledge has accumulated, and technology has improved over five decades, such that O’Neill’s original concepts can be updated to a buildable design.
  • Low-cost, fully reusable launch vehicles — which existed only on paper in 1975 — are now a reality on the launch pad.
  • The open-source movement has demonstrated a path to the democratization of technology that was not envisioned in O’Neill’s era.
  • Increasingly powerful artificial intelligence tools now enable a relatively small science and engineering team to address large, complex design questions at a level impossible during O’Neill’s time.

Scope and Boundaries of the OSSD Project

Scope of the Engineering Design:

  • A place where people, including families, can safely live on a permanent, economically self-sustaining basis.
  • Nominal population target: 1,000, with analysis covering populations from 100 to 10,000 for comparison.
  • Designed for direct comparison to the 10,000-person NASA Ames summer study and the British Interplanetary Society (BIS) Avalon project.
  • Positioned as a component in a cislunar economic network (not required to be autarkic or totally biologically self-sufficient).
  • Assumes the baseline human species; human modification or enhancement is explicitly out of scope.
  • Design target: 1 gravity or a high fraction of 1g (since humans have evolved over millions of years on Earth, and the minimum gravity level for long-term human thriving in space has not been firmly established).

What’s included:

  • Engineering design for a rotating space settlement.
  • Examination and development of assumptions related to available construction materials and their costs.
  • Exploration of the legal, treaty, and economic prerequisites needed for the engineering design to be feasible.
  • Investigation of resilience to both natural and artificial assaults, with particular attention to electromagnetic hazards, biological threats, and meteor/space debris strikes.

What’s excluded (The idea being “Don’t boil the ocean”; i.e., focus only on the space settlement design, not all the other ancillary infrastructure and supply chains):

  • Lunar mass drivers
  • Lunar mining technology
  • Construction shacks
  • Asteroid mining technology
  • Launch vehicles
  • In-space transport vehicles
  • Detailed design of robotic construction equipment
  • Weapons systems for settlement defense that are not necessary to protect against natural phenomena
  • Military plans relating to settlement defense

What Happens Next? The Five-Year Roadmap

The project will proceed through disciplined, question-driven workshops rather than attempting to design everything at once:

  • NSS, led by the BSTA, will organize high level workshops to define specific design input questions, to be drafted at this fall’s Space Settlement Summit and subsequently flowed down to subordinate working groups.
  • The questions will be categorized into a few topic areas to help assign subject matter experts, such as High-level Requirements, Agriculture/Biological, and Physical/Construction.
  • The BSTA will assign Rapporteurs to lead these working groups in each question area.

NOTE: Each Rapporteur is expected to organize their work as they see fit and report at least annually to the BSTA with a readout of their progress, including draft recommendations. The normal working method will be workshops, but other means can be used. Unlike the ITU-T, which rotates its meetings across continents, workshops will typically be held in the USA, although this is not strictly required. Rapporteurs are unpaid volunteers, typically with jobs in the space industry

  • In a workshop, carefully framed draft questions will be presented and tagged with a dependency (i.e., TOR, Economic Model, Location, etc.) The questions form the intellectual backbone driving the entire OSSD project.
  • The workshop groups will do the hard work to define good questions with the core philosophy that “Good questions drive good answers.”
  • Workshops will cover a focused set of questions and continue until a Recommendation is produced to define a design output.
  • Target: After five years, the accumulated Recommendations will add up to a complete, buildable engineering design.

The Questions:

The following list is an evolving work in progress as of the date of this post, of potential questions to be finalized by the BSTA and then flowed down to the working groups to flesh out the details. It is by no means complete.

  1. What is the target reliability/safety standard? (Depends on TOR)
    Options range from aviation-like to nuclear-plant-like, to “ISS-like”. Telecom, chip, or automotive standards? This decision drives redundancy, inspection cadence, acceptable risk to children, and the critical safety-vs-uptime trade-off (space habitats cannot have downtime). It also requires choosing a reliability level target (e.g., 5-sigma vs. 6-sigma) and deciding which parts of the habitat are held to which standards.
  2. What are the core services provided to residents? (Depends on TOR – for discussion)
    Includes housing space per person, privacy, recreation, food variety, internet latency, and governance/rights baseline. The question invites comparison to services provided by a small town on Earth and asks how to avoid the tragedy of the commons for “free goods,” while also defining the proper limits of what planners/designers should dictate.
  3. What is the Economic Model? (Depends on Q4)
    This involves answering fundamental questions like: How will settlers add economic value? How will the settlement be economically sustainable?
  4. Where exactly in cislunar space will the settlement be located? (Depends on TOR)
    Candidate locations: Near-Rectilinear Halo Orbit (NRHO), distant retrograde orbit, Earth-Moon Lagrange (EML)1/EML2 halo, high lunar orbit, or EML4/EML5. Location dramatically affects eclipses, station-keeping, communications, debris environment, thermal design, and the economic model itself.
  5. What is the logistics doctrine with Earth? (Depends on Q3, Q4)
    Covers cadence for spares and consumables, allowed lead times, acceptable downtime, and precisely which items must be “topped off” and how often. Items such as trace elements, pharmaceuticals, replacement electronics, specialty foods, nitrogen/argon, etc. need to be defined. Spares/consumables strategy may itself be an outcome of the economic model rather than a question per se.
  6. What population size and target demographics are required for social stability? (No dependency)
    Includes sex ratio, age distribution, and other demographic factors. Questions about non-cisgender humans are out of scope. This is not to exclude them explicitly, but the intent of the question is to focus on critical biological issues.
  7. What population size is required for operational stability? (No dependency)
    Focuses on skill sets, trades, and degree of automation needed for settlers to maintain safe operations. May depend on downstream recommendations about agriculture and other operations.
  8. What population size is required for economic viability? (Depends on Economic Model)
    Considers export/service revenue versus internal labor needs, degree of specialization, downtime tolerance, training pipeline, and explicitly excludes a small population of the very rich as a viable model.
  9. What population size, including pets, is required for mental health? (No dependency)
    Studies have found that 1 in 20 people who overwinter in Antarctica develop serious mental health issues. This suggests that a population of ~200 (typical Antarctic winter-over size) may be too small, or that aspects of the Antarctic station model need correction for space application.
  10. Therefore, what is the minimum viable steady-state population? (Depends on the Q6, Q7, Q8, Q9)
    A synthesizing question that derives a minimum that satisfies the criteria from the related questions, with a suggested floor of 100 occupants.
  11. What governance model applies? (Depends on TOR)
    The TOR states that the settlement is assumed to be under the legal jurisdiction of the launching state. The question explores issues arising from applying the laws of the launching state to the settlement and how those issues can be resolved.
  12. What Ownership Model Applies? (Depends on Economic Model)
    This question is strongly linked to the economic purpose of the settlement, and should cover corporate ownership/company townships, co-ops, condominiums, employee-owned corporations, and other models.
  13. What international legal regime is required to allow the first settlement to be funded? (Depends on TOR)
    Focuses on what legal interpretation of the Outer Space Treaty is necessary to permit construction of a settlement in orbital space.
  14. What maximum rotation rate (rpm) is acceptable for a multi-generation population? (Depends on TOR)
    Because artificial gravity is fixed at approximately 1g, the rotation rate directly sets the required radius, which in turn drives structural mass and construction approach. Why 1g? The TOR states: “Since the minimum gravity level for human thriving has yet to be firmly established, the design target will be either 1 gravity or a high fraction of 1 gravity…” I’ve posted on the topic previously.
  15. What radius/geometry follows from the g level and rpm? (Depends on Radius, also TBD)
    Explores torus vs. cylinder vs. multi-ring vs. hammerhead configurations, habitable deck layout, and zoning.
  16. What is the docking/visiting vehicle strategy relative to rotation? (Depends on Q15)
    Will there be total spin-down? Will there be a non-rotating hub, and if so, how will the transfer from rotating-to-nonrotating spaces be accomplished?
  17. What radiation standard do we design to for families/children? (Depends on Q1)
    Annual dose targets, pregnancy limits, and Solar Particle Event shelter requirements need to be specified. Note that Medevac doesn’t help for chronic exposure to Galactic Cosmic Radiation.
  18. What shielding approach meets Q17 at minimum mass/cost? (Depends on Q17, Q4)
    Decisions on how bulk shielding (e.g. water and/or regolith) will be distributed, need to be made, accounting for storm shelters. Shielding-as-storage, active shields, and layered shields should be considered.
  19. Where does shielding mass come from? (Depends on Q4, Q18)
    Weigh the options of Earth-launched vs lunar-derived vs extracted from an asteroid, keeping in mind that sourcing material for initial habitats may change for future growth.
  20. What closure level is required to be “permanent” with imports allowed? (Depends on Q2, Q3, Q4, Q5)
    Define which consumables must be recycled (e.g., water, oxygen, nitrogen) vs what can be imported.
  21. What food system meets nutrition, variety, and psychological considerations at minimum mass/power? (Depends on Q10, Q20, Q25)
    The hydroponics/vertical farming mix, lighting strategy, protein plan, and storage buffers all need to be determined, fully considering the recycling system and ecological balance of the biosphere.
  22. What will be the atmosphere model and fire safety regime? (Depends on Q1, TOR)
    The total pressure, O₂ fraction, diluents (N₂/Ar), toxic pollutants control, and fire suppression doctrine all need to be determined.
  23. What water/waste architecture achieves Q20 with acceptable failure modes? (Depends on Q1, Q2, Q20)
    Water recovery, sanitation, pathogen control, waste processing, and a plan for “what if” contingencies need to be defined.
  24. How can an overly clean habitat environment be avoided? (TBD)
    Children who grow up on farms have very low allergy rates; we want to make sure kids in the settlement are exposed to diseases to develop their immune systems.
  25. What total power level is required (steady state and peak)? (Depends on Q1, Q3, Q21, Q23)
    This will be a cumulative summing the contributions from the habitat, agriculture, industry, propulsion, and reserves.
  26. What power source architecture is optimal in cislunar space?(Depends on Q4, Q25)
    Solar vs nuclear vs hybrid, taking into account storage needs, safety considerations, and maintenance.
  27. What thermal rejection system is required? (Depends on Q25, TBD)
    This will drive radiator design, cooling system loops, heat reuse, zoning, and orientation constraints.
  28. What minimum local manufacturing/repair capability is required? (Depends on Q5, Q9)
    Operations to consider include, but are not limited to, planning for spare parts, maintenance of seals/filters, facilities for machining, electronics repair, additive manufacturing, and QA.
  29. What structural concept meets loading requirements, while taking into account micrometeoroids, internal pressure, and rotation rate, and minimizing mass? (Depends on Q4, Q15, Q18, Q22)
    At a minimum, requires consideration of materials, compartmentalization approach, Whipple shielding design, and pressure hull segmentation.
  30. What is the assembly and spin-up strategy? (Depends on Q4, Q15, Q18, Q29)
    Requires decisions on which modules are preassembled vs built on-orbit. Will the construction be carried out robotically or by crew? What is the optimal timing of when shielding is added, taking into account how balance will be maintained when rotation is initiated?
  31. What is the fault-tolerant operations concept? (Depends on Q1, Q10, Q28)
    This will help determine the staffing requirements, levels of training, emergency response procedures, maintenance cycles, inspection needs, spares policy, and cross-training.
  32. What are the top “design basis accidents” and how are they handled? (Depends on Q1, Q22, Q23, Q29, Q31)
    Scenarios include, but are not limited to, fire, depressurization, toxic release, collision, loss of rotation control, and loss of power.
  33. What is the growth path from the minimum viable system to a larger one? (Depends on Q15, Q18, Q29, Q30)
    This question will help to decide when to add rings/modules, how governance and economy scale, and how to avoid redesign.

O’Neill’s Vision of Free Space Settlements is Closer Than Ever

The OSSD project is a major strategic step for the NSS. After completing and publishing the foundational 2021 workshop proceedings in both accessible paperback and soon-to-be-released premium hardback formats, the organization is now moving from vision and discussion to disciplined, engineering-driven action. By framing the project around a rigorous, design input question methodology with clear scope boundaries, plans to assign rapporteurs, workshop processes, and a five-year horizon for producing buildable recommendations, the NSS is taking the lead as the honest broker and convening authority capable of coordinating the complex, multi-disciplinary work required to turn O’Neill’s dream of rotating space settlements into engineering reality.

The interactive workshop approach using carefully crafted design questions demonstrates a commitment to grassroots community input and iterative refinement rather than a top-down prescription. The careful separation of in-scope engineering/systems issues from excluded topics (launch vehicles, mining technology, mass drivers, etc.) shows a mature project management philosophy designed to keep the effort focused and achievable.

In summary, the OSSD Project will bridge the inspirational legacy of Gerard K. O’Neill and the 1975 NASA-Ames study with the practical realities of 2026: reduced launch costs via reusable rockets, open-source methodology, powerful leverage of AI, accumulated knowledge, and an organized NSS ready to lead the next phase of space settlement engineering. This initiative is positioned as the logical next step after the SSW book — turning the “long list of areas for future research” identified in that publication into concrete, actionable engineering questions whose answers will collectively constitute the first credible, buildable design for a rotating space settlement.

I cohosted The Space Show with Dr. David Livingston on August 7 when Dale Skran was our guest, sharing more details about the project. You can listen to the archived show on The Space Show website. Visit the NSS OSSD project website for the latest updates. Let’s make this happen!

Artist’s rendering of what the interior of a 125m diameter rotating space settlement might look like; another possible outcome from the NSS OSSD project. Credits: Bryan Versteeg / Spacehabs.com
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Homing in on the Gravity Prescription

Image of the JAXA Kibo module on the International Space Station which houses the MARS short arm centrifuge for artificial gravity studies. Credit: NASA/JAXA

The Gravity Prescription (GRx), a term first coined by Dr. Jim Logan, refers to the minimum “dosing” of gravity (level and duration of exposure) to enable healthy conception, gestation, birth and normal, viable development to and throughout adulthood as a human being…over multiple generations. It should be noted that the GRx can be broken down into at least three components: the levels needed for healthy pregnancy (conception through birth), early child development, and adulthood.

The Japan Aerospace Exploration Agency (JAXA) has been studying the adult gravity prescription for mitigation of mammalian physiological issues that arise in space due to microgravity using mice for about a decade. To conduct this research, they’ve been using the Multiple Artificial-gravity Research System (MARS) short arm centrifuge in the Kibo module on the International Space Station (ISS). This will help us understand what dosing level of gravity is required to prevent the myriad of health issues (e.g., serious reduction in bone and muscle mass, ocular changes, weakening of the immune system – there are many more) that arise in mature adults when exposed for long periods to microgravity, to inform countermeasures for long-duration spaceflight and settlement.

By way of background, I reported back in 2021 on JAXA’s first long-term mouse study comparing mice reared under microgravity conditions to a cohort raised under 1g artificial gravity in the MARS centrifuge, which found that Earth-normal artificial gravity appears to prevent the negative health effects of microgravity. In the same post, I provided an update upon publication of the results of a second experiment executed a couple of years later, which tested mice in Moon gravity and found that 1/6g prevents muscle atrophy in mice, with the downside that this level of artificial gravity cannot prevent changes in muscle fiber (myofiber) and gene modification induced by microgravity. There appeared to be a threshold between 1/6g and Earth-normal gravity, yet to be determined, for skeletal muscle adaptation. Then in 2023 we got a few more data points helping us zero in on the right dose, at least for the adult GRx, between Moon and Earth levels of gravity.

I mentioned this new preliminary data in my presentation at ISDC 2024 on how the GRx may impact the future of space settlement. The results came from a NASA-funded experiment in cooperation with JAXA, headed by Dr. Mary Bouxsein and collaborators, that studied adult mice launched to the ISS on SpaceX CRS-27. The mice were split into four groups and dosed in the MARS centrifuge at four levels of gravity (microgravity, 0.33g, 0.67g, and 1g). The results were presented at the American Society for Gravitational and Space Research (November 2023). Still, no formal paper had been published at that time, only an abstract from the conference talk. Preliminary results showed that hindquarter muscle strength increased commensurate with the level of artificial gravity, indicating that spaceflight-induced atrophy can be mitigated with artificial gravity – more is better. Now the full study has finally been published in Scientific Advances with further details.

After each of the cohorts were individually treated to the four gravity levels in the MARS centrifuge and returned to Earth, the mice were euthanized and the researchers examined their soleus muscle (the calf muscle which is very sensitive to gravity levels), along with strength tests and blood biomarkers.

Key findings included:

  • Muscle shrinkage (atrophy): In microgravity, the soleus muscle fibers shrank noticeably. At 0.33g, the muscle cross-sectional area was largely preserved—meaning it didn’t lose much mass. Higher gravity (0.67g and 1g) also protected muscle size.
  • Muscle fiber type: Muscles have different fiber types—slow-twitch (good for endurance) and fast-twitch. Microgravity causes slow fibers to switch to fast ones. 0.33g partially prevented this switch, but 0.67g fully stopped it, keeping the muscle composition closer to normal.
  • Muscle function: Strength tests (like grip strength) and electrical measurements showed that 0.67g was enough to maintain overall muscle performance. Lower gravity levels did not fully protect function.

The study also found 11 blood metabolites (small molecules that are intermediate or end products of metabolism) that changed depending on gravity level. These could serve as future biomarkers to monitor astronauts’ health without invasive tests.

Why does this matter? This is the first experiment to identify the adult GRx thresholds for muscle health. It suggests that 0.33g (close to Mars-level) helps prevent muscle weakening, but titrating to 0.67g is needed to fully maintain strength and normal muscle condition. For future space stations or vehicles with rotating sections to create artificial gravity, this information is valuable: partial gravity helps, but at least 0.67g is better for long-term missions. Crucially, these results could inform the spin-rate specifications for a Mars Cycler to generate artificial gravity to maintain muscular function for travelers to and from Mars.

In short, the paper shows that even moderate artificial gravity could mitigate the musculoskeletal problems astronauts face in space, helping keep crews healthier on deep-space journeys. The research used careful controls, multiple measurement methods, and advanced analysis to reach these clear conclusions.

The bigger question is what is the GRx for reproduction? If permanent settlements are to be established in space, they should be (in the long run) at destinations that enable biological self-sustainability, meaning we will want to have healthy children and raise families there as we expand out into the solar system.

One study conducted by Japanese researchers in 2019 aboard the ISS suggested that mouse embryonic growth may be possible in microgravity. But this experiment was only 4 days of embryo development, which took place after conception. Another study of pregnant mice from the shuttle era found serious issues with brain development after exposure to microgravity. These are just snapshots of embryo and later fetus development, and only in microgravity. There still have not been rigorous scientific experiments covering the full mammalian reproductive cycle through all its phases under variable gravity conditions mimicking the Moon, Mars, or higher levels below that of our home planet.

Conceptual AI generated image of an expectant mother in Earth orbit under appropriate GRx dosing conditions after mammalian reproduction has been validated via higher animal models through all stages of pregnancy for a safe level of artificial gravity. An appropriate level of radiation shielding would also be required and is not shown in this illustration. Credit: MS Designer

It is vitally important as the private space stations begin to replace the ISS and space tourism takes off (including maybe even hotels on the Moon), that we understand the risks and implications for having babies off Earth in lower gravity environments. Alex Layendecker, the founder of the nonprofit Advanced SpaceLife Research Institute (ASRI), told me the following in an interview about his Green Paper on Sex in Space: Consideration of uncontrolled human conception in emerging space tourism:

“With mass access to space, we’ll soon have groups of individuals going up solely for vacation/leisure purposes, and you can be assured some of them will be engaging in sexual activity.  While it would be absurd to try to implement or enforce laws preventing sexual activity in those environments, the dangers associated with potential conception still exist.  What is critically needed at this point is a better collective understanding of those dangers, their mitigation, and for space companies to be able to provide those paying customers with enough information that informed consent can be established – space is inherently dangerous already, and people launching into space are briefed on that.”

Besides JAXA and some limited research by NASA, there are just a couple of organizations dedicated to studying the GRx for reproduction. ASRI based at Cape Canaveral and a Dutch company called SpaceBorn United. SpaceBorn has space missions planned in the next few years using their ARTIS (Assisted Reproductive Technology in Space) platform, focused on mammalian conception and early embryo development, with a prototype “space-embryo-incubator” capable of treating samples with adjustable artificial gravity. Initial missions will send this device to space with male and female mouse gametes, where in vitro conception and 5-6 day embryo development will proceed under artificial gravity conditions. The embryos will then be cryogenically frozen and returned to Earth where, if approved, they will be implanted in natural wombs, where the pregnancy will progress on Earth. If successful, subsequent phases over the next couple of decades will focus on increasing stages of pregnancy in space and early embryo development on the Moon.

But SpaceBorn’s platform is a small, automated self-contained centrifugal device operated in microgravity. To really study the GRx for mammalian reproduction, a fully equipped (preferably crewed) variable gravity biolab large enough to rear lower organisms from conception through pregnancy to birth, maturing into adulthood – over multiple generations and progressing successively in higher mammals – would be required. A very tall order! But there are reasonable and well-thought-out concepts for such facilities I’ve explored here previously.

Currently, there are only a couple of companies with rotating space stations in their strategic plans to provide larger-scale artificial gravity laboratories that could be used for reproductive studies. Vast Inc., a well funded, privately held startup, explicitly lists an Artificial Gravity Station targeted for around 2035 in its official product roadmap, a long cylindrical design that will rotate end-over-end at ~3.5 RPM to create artificial gravity for long-term habitation. It would build on their modular (non-rotating) Haven-1 module currently planned for launch in 2027 and the follow-on Haven-2 station which would gradually add units, eventually leading to a 9-module configuration slated for 2032.

Conceptual illustration of Vast Space Haven-2 nine module configuration space station that could be placed in Earth orbit as soon as 2032. Credit: Vast Space

Above Space, with aspirations for rotating wheel type space stations in the 2030s, has significant engineering and funding hurdles, but is the only other player that has plans for variable gravity facilities in space.

In my presentation at ISDC2024 linked earlier in this post, I advocated for determining the GRx for reproduction sooner rather than later, especially given Elon Musk’s timelines for colonizing Mars. As Musk has made clear for years and with his recently revealed SpaceX compensation package tied to it, his vision for the company is to make humanity multiplanetary and build a city on Mars with a million people. Up until recently, he was projecting mid-century to achieve that milestone. His shifting focus from Mars to the Moon aside, does he expect the population of his Martian colony to be composed of just adults? Musk, who has warned of population collapse and low fertility rates here on Earth as one of humanity’s biggest challenges, has been quoted as saying, “People are going to have to revive the idea of having children as a kind of social duty. If you can, and are so inclined, you should. Otherwise civilization will just die.”

Image of Elon Musk holding his son X AE X-II after Grimes gave birth to him in May 2020. Credit: Elon Musk

I’m pretty sure he envisions that the people occupying his city on Mars will want to have children there. And he’d probably want to know the GRx for reproduction well before significant numbers of people began migrating there to stay. A variable gravity research facility in low Earth orbit dedicated to studying mammalian physiology, including reproduction in less than 1g, could be built using SpaceX hardware and would not cost much more than Musk’s pocket change, but I’ve seen no indication that this is a priority for him.

Of course, there are others, affectionately called O’Neillians, who say we know 1g works, so let’s not waste time and just get started building rotating space settlements like Kalpana One, a 500m diameter starter unit located in equatorial low Earth orbit. Shielded by Earth’s magnetic field and therefore requiring less mass for radiation shielding, it would be much easier to accomplish than the enormous miles-long settlements O’Neill envisioned to be placed out at Earth-Moon Lagrange Point L5. The attractiveness of this approach (in LEO) may be waning with the rise of AI and what will likely be a proliferation of orbital data centers in the next few years. Cowboy Space has just filed with the FCC for a literal Stampede of 20,000 satellites adding to the queue of companies seeking regulatory approval for their megaconstellations, including Blue Origin’s Project Sunrise (51,600), Starcloud (88,000), and SpaceX’s 1 million satellites, all in sun-synchronous orbits ranging from 500 to 2000 kilometers. It may be getting pretty crowded up there soon, increasing the risk of collision with large cross-section space stations that are not easily maneuvered out of the way.

Personally, my view has evolved on the urgency for determining the GRx for reproduction on the Moon or Mars. I still hold that healthy human reproduction in lower-gravity environments is highly uncertain, given millions of years of evolution in Earth’s gravity, and carries a substantial risk of complications at every stage of reproduction. Being inspired by O’Neill, I was admittedly biased toward his approach to mitigate these risks and had a preference for spacious artificial gravity worlds. This led me to believe that if we confirmed through studies of the GRx for reproduction that having children in less than 1g could lead to dangerous complications and, therefore, be morally wrong, the information might bend the arc of space development toward free space settlements. Knowing we could not have children on the Moon or Mars might start to change the mindset of many space settlement advocates, whom the great science fiction author Isaac Asimov called planetary chauvinists, leading to diversion of resources toward building the infrastructure needed to construct rotating space settlements like Kalpana. I’m old enough to remember that O’Neill invented one of the key technologies for building these huge structures: a mass driver intended to be placed on the Moon to launch massive amounts of lunar regolith into space so that it could be processed into radiation shielding for these colonies. Advances in robotics, in situ resource utilization (ISRU), in-space assembly, life support systems, and many other technologies are needed to enable O’Neill colonies. Many of them are proceeding at pace anyway, but I thought that if we found the GRx for reproduction was not less than 1g, it would put a sense of urgency around these efforts.

However, it looks like market forces may be changing all this. I did not anticipate Elon Musk advocating for mass drivers on the Moon. Though he says they would be used for launching SpaceX’s AI satellites, the infrastructure for ISRU and electromagnetic launchers looks like it may be coming to Luna sooner than we expected and can certainly be retooled to fling regolith into space for shielding rotating space settlements, even larger ones, if the drive (and markets) are there.

But rather than the GRx for reproduction being the determining factor for where we settle space – planetary surfaces or free space colonies – a split life cycle may be the solution. This approach, credited to Kelly and Matt Weinersmith in their book A City on Mars, suggests using both destinations! As clarified in a presentation at ISDC2024 by Dale Skran, Chief Operating Officer & Senior Vice President of the National Space Society, this new way of thinking (not an official position of NSS) acknowledges that we probably need Earth normal gravity for having children and suggests that a rotating space station birthing center be placed in orbit above surface colonies on the Moon or Mars. Couples would conceive, bear children, and raise them in a healthy artificial gravity crèche, allowing them to mature to early adulthood, after which families or individuals may choose to remain in space or relocate to the low-gravity surface communities below.

So research by Dr. Bouxsein et al. may be homing in on the adult GRx, with the results from their study paving the way for practical countermeasures against health issues adult astronauts will face in microgravity on long-duration missions in space. But the artificial gravity dose level for reproduction needs much further study before we can safely say biologically self-sustaining space settlements in less than 1g will be possible. Until then (and after, if the answer is no), split life cycle communities may be the strategy for an expanding population migrating out into the solar system and beyond.

Artist’s impression of the interior of Kalpana One, a cylindrical rotating colony providing Earth normal artificial gravity for healthy living in space. With the coming proliferation of AI orbital data centers later this decade, this approach may lose favor in LEO, but could be one possible in-space component of a split life cycle solution for settlement of the Moon or Mars. Credits: Bryan Versteeg / spacehabs.com

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Wohrad: The first serious design of an artificial gravity space station

The Habitat Wheel (Wohrad). Redrawing of Fig. 84 from The Problem of Space Travel (Noordung, 1929). Color codes identify various categories of human activities – Blue: Sleep; Yellow: Hygiene; Green: Food; Red: Work and leisure, Grey: Circulation and ancillary spaces. Image and minor edits to text based on Figure 16 of the author’s paper. Credits: Fig. 16, from paper by Sandra Häuplik-Meusburger / Used under CC by 4.0

Before O’Neill’s Stanford Torus. Before Stanley Kubrick’s Space Station V in 2001: A Space Odyssey. Before Von Braun’s Space Wheel. There was Hermann Potočnik’s “Wohnrad”, or Habitat Wheel. Writing under the pseudonym Herman Noordung, his 1929 book Das Problem der Befahrung des Weltraums (The Problem of Space Travel) lays out the first serious architectural design of a rotating space station intended to incorporate artificial gravity for human habitation. In the forthcoming issue of Acta Astronautica coming out in April, space architect Sandra Haeuplik-Meusburger examines the early space station architecture via a digital and physical reconstruction. Noordung’s design is considered a milestone in space habitat concepts predating practical spaceflight by many decades.

Noordung’s Wohnrad provided one of the earliest fully developed technical designs for a rotating space station. Unlike speculative ideas before it, his design included three components with specific functions — a rotating Habitat Wheel spinning to create artificial gravity for living spaces at the rim. A free flying lab called the Observatory for scientific discovery. And a much larger sun facing solar power plant (Machine Room), also free flying, which would provide power and life support for the Observatory. Earlier scientists (e.g., Konstantin Tsiolkovsky, Hermann Oberth) suggested early ideas for space stations, but Noordung was the first to produce comprehensive architectural and mechanical drawings of one.

Noordung’s rotating wheel was the first space station intended to provide centrifugal force artificial gravity — a hugely influential idea that foreshadowed decades of later space habitat concepts including Von Braun’s Space Wheel in the 1950s, space station depictions in seminal science fiction movies such as Kubrick’s 2001: A Space Odyssey and of course, O’Neill’s Stanford Torus which didn’t come along until 1975. His design not only addressed physiological needs (countering weightlessness) but architecturally integrated human life support, observation, and workspaces into one cohesive structure — a novel systems-level vision at the time.

Artist impression of the interior of a Stanford Torus. Credits: Don Davis / NASA

Haeuplik-Meusburger’s paper underscores how Noordung’s concept was architecturally rich — detailing spatial organization, functional modules, interior arrangements, including the logic for transitions between rotating and non-rotating sections. Her reconstruction work though modern digital modeling and 3D printed archetypes reveals architectural relationships between modules in more detail than prior historical treatments. Digital reconstruction of the original design provides new insights into proportional relationships, functional layout, and how Noordung envisioned human interactions in space. 3D printing prototypes helped the author reinterpret design logic in ways not possible from 2D archival drawings.

Lets dive in to the details. The author uses a mixed-method architectural and design research approach combining historical analysis with digital and physical reconstruction of Noordung’s original space station concept. She starts by collecting and studying the original material from Noordung’s 1929 book Das Problem der Befahrung des Weltraums — including diagrams, plans, textual descriptions, and images of the Wohnrad (Habitat Wheel) and associated modules (Observatory and Machine Room). The historical review also places the design in the context of other early spaceflight concepts and later influences (e.g., von Braun’s work and science-fiction imagery). This established a baseline understanding of the original design intent and the architectural logic behind the space station.

Next, Haeuplik-Meusburger created a virtual reconstruction taking historical, two-dimensional drawings and texts and translating the original figures into a detailed 3D digital model, probably using CAD or architectural modeling tools (the paper did not specify the software explicitly). This digital reconstruction allowed her to visualize and analyze the spatial layout, proportions, and structural relationships that aren’t obvious in the original flat plans.

After the digital model was created, the author 3D printed a physical prototype enabling tangible exploration of how spaces and modules relate — a method often used in architecture to test and critique design concepts. Moving between digital and physical forms helped identify aspects of the design that might be missed solely through drawing interpretation. Throughout the reconstruction, she provided an architectural interpretation of the design informed by human factors to understand how people would live, move, and interact with spaces under rotational artificial gravity — a layer of analysis beyond mere geometric reconstruction.

The author’s 3D modeling revealed the relationships between modules more clearly than the original drawings. Her findings included unexpected details about occupant circulation in the Habitat Wheel (e.g., access paths, stairs/elevator placement) and how spaces might feel or operate under rotation. This is significant because Noordung’s original descriptive text and flat plans alone could not convey the experience of inhabiting these spaces — a key gap filled by the reconstruction method.

The Habitat Wheel interior is partitioned into activity spaces and individual rooms in the outer rim structure accessed via a central corridor. This is where the crew would spend most of their time close to Earth-like conditions. In the illustration provided above by the author, the layout of the functional areas is shown color coded by the activities envisioned by Noordung.

His original design pegged the radius of the Habitat Wheel at 15 meters with a spin rate of 7.5 rpm resulting in level of artificial gravity of 0.94g. What we know now from many decades of research on human physiology under spin gravity conditions, this arrangement was impractical. The rate of rotation and relatively short radius of the station would likely result in significant Coriolis effects causing vestibule discomfort and disorientation in the occupants. Still, Haeuplik-Meusburger’s analysis places Noordung’s work on firm architectural and design grounds including the practicality of the Habitat Wheel as a concept with enduring lessons for how we might design rotating habitats in the future.

Realizing the issue with the Habitat Wheel’s short radius and high rotation rate, Haeuplik-Meusburger makes use of a Comfort Chart developed by Theodore Hall, a space architect and recognized expert on artificial gravity. The tool is a graph with habitat radius plotted against angular velocity with comfort zones where disorientation is minimized mapped on the plane of the chart. Armed with this information, the author proposes increasing the radius and reducing the rotation rate to a tolerable level, or even considering partial gravity levels of 0.2 to 0.5 g. Incidentally, Hall coauthored a paper on a Mars Cycler with artificial gravity covered by SSP last November.

Exploded axonometric view of the Habitat Wheel components with dimentions according to The Problem of Space Travel (Noordung, 1929). Credit: Fig 14 from paper (with minor caption text edits) by Sandra Häuplik-Meusburger / Used under CC by 4.0

Haeuplik-Meusburger’s use of physical and virtual models helps us better interpret how Noordung imagined habitability and use. For example, spatial organization suggests how living quarters, laboratories, and circulation were meant to function under artificial gravity conditions. In addition, her research clarified how functional logic (like the location of service spaces versus leisure or observation spaces) reflected deliberate design choices, not just schematic ideas.

The Observatory was intended primarily for scientific observation and microgravity research. It was designed to be free flying tethered to the Machine Room which provided power and breathable air via cables and flexible tubes, respectively. The weightless environment would minimize motion enabling equipment to operate more effectively in the absence of vibration. The facility would be equipped with instruments for astronomical observations, Earth monitoring, and telecommunications. The low-gravity environment made precise pointing of telescopes easier and instrument mounting simpler. In addition, there was a laboratory for performing experiments in microgravity. Noordung envisioned the station not just as a place to live but as a scientific platform in orbit, decades before orbital observatories and research facilities became reality.

One notable aspect of the Observatory was that the facility was intended to be placed in geostationary orbit 35,900 km above the Earth’s surface completing one orbit per day fixing it in the sky above the same location. Noordung suggested it could be used as a telecommunications relay station seventeen years before Arthur C. Clark introduced the concept of a communications satellite in a 1945 article in Wireless World.

The Machine Room was the station’s primary power plant, the earliest know example of a solar thermal-engine for use in space. The system featured a 120 meter concave mirror permanently facing the sun and focusing sunlight on heat pipes, whose working fluid would drive a turbine to generate electricity. The condenser and radiator in the thermal-engine circuit would be located at the back of the facility shielded from sunlight. Noordung chose nitrogen as the working fluid for the system over water as it results in significantly lower condenser temperature, leveraging the extreme cooling of the vacuum of space. The Machine Room was the largest facility of the space station containing the main solar power plant with storage batteries, a large transmission station, and a ventilation system serving the Observatory. Noordung’s design was remarkably forward-thinking, addressing real thermodynamic and space-environment challenges in a way that holds up conceptually even now.

One of the most innovative aspects of the space station was the design of the airlock located at the hub of the Habitat Wheel. In addition to addressing the core functions of maintaining internal atmospheric pressure during ingress/egress, allowing safe transition to vacuum and conserving breathable air, Noordung had a novel solution for resolution of the rotating-to-inertial frame problem created by a spinning space station – a rotating airlock chamber capable of counter-rotation.

Since the station’s rim would be rotating to generate artificial gravity and is mechanically connected to the hub, obviously the airlock would be rigidly attached to this rotating structure and have the same angular momentum as the station. Docking spacecraft or individuals on EVAs would have to synchronize their rotational motion to match the door of the airlock, which complicates entry or exit. Noordung’s solution was a system in which the astronaut would enter the airlock (e.g. when exiting the station) while it is rotating with the the habitat wheel. The chamber would be then mechanically driven to de-spin in the opposite direction of the station’s spin. When its angular velocity cancels out the station’s rotation, the airlock would become inertially stationary relative to space outside of the ship, upon which the outer hatch could be safely opened. Noordung’s design included ball-bearing systems, rotational drive mechanisms and sealed rotational interfaces implying that there would be a structural ring allowing relative motion between rotating and non-rotating sections, a mechanical transmission capable of controlled deceleration and a pressure sealing mechanism across a rotating joint. The latter requirement is mechanically demanding and remains challenging even in modern engineering – but he anticipated the mechanical need even though he did not mathematically model these issues in modern terms.

As an aside, the airlock concept was not the first ever conceived (airlocks were already used in mining, tunneling, and civil engineering projects on Earth in those times), but it is one of the earliest detailed proposals of an airlock in spaceflight literature of that period, specifically designed for a space station and EVA-type operations.

Since the station’s life support system was not intended to be ecologically closed and the facility was not intended to be crewed permanently, Noordung understood that supplies needed to be conserved as resupply from Earth would be expensive, especially prior to the advent of reusable rockets. Thus, his design pumped precious air in the airlock back into the station rather then vent it to space upon exit.

Original illustration of Noordung’s airlock concept (Figure 76 in The Problem of Space Travel, Noordung, 1929) Top view of the exterior door and section through the rotating airlock of the Habitat Wheel.  Credit: text by Sandra Häuplik-Meusburger with minor modification / Used under CC by 4.0

Haeuplik-Meusburger’s modeling and 3D printed physical reproductions reveal clearer spatial and operational insights about how the airlock access points functioned within the overall station layout showing relationships to the hub, circulation paths, and machinery areas. These aspects were not apparent in Noordung’s original 2D drawings as they compressed depth and circulation in ways that are hard to interpret from flat figures. For example, the air lock’s position in the axial hub is not incidental. It sits in a circulation node, not an isolated compartment. Her reconstruction reinforces that the airlock was not an accessory to the station but was embedded in a carefully organized hub as part of a systems cluster including machinery, life-support infrastructure, low-gravity workspace and external access. Seeing that integration clearly in 3-D strengthens the argument that Noordung was thinking in systems-architectural terms, one of the main conclusions of the paper. This systems integration is easier to recognize when viewing the station as a volumetric structure rather than separate diagrams.

Haeuplik-Meusburger’s analysis is innovative in how it reconstructs Noordung’s foundational ideas that deeply influenced both the technical lineage of space habitat design, and the cultural imagery of space stations in science and fiction. Her methods demonstrate how digital/physical reconstruction can deepen understanding of design concepts that were never constructed. Finally, the work reveals architectural details and ergonomic considerations that had previously been obscured in the original diagrams. By re-evaluating Noordung’s work with new modeling techniques, the paper provides both historical clarity and design insight that enriches our understanding of Noordung’s prescient visions for living in space, many of which were ahead of his time.

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TESSARAE for orbital biolabs and more

Conceptual illustration of an orbital biolab constructed using TESSERAE architecture. Credit: Aurelia Institute

At last year’s International Conference on Environmental Systems (ICES), Aurelia Institute Vice President of Engineering Annika Rollock presented a paper on development of an orbital TESSERAE habitat to conduct biotechnology research. TESSERAE (Tessellated Electromagnetic Space Structures for the Exploration of Reconfigurable, Adaptive Environments) covered previously on SSP, was conceived and developed by Ariel Ekblaw, cofounder and CEO of Aurelia as part of her doctoral thesis at MIT. A TED Talk by Ekblaw from last April provides more detail on the concept with footage of prototypes demonstrated in space on the International Space Station (ISS).

The paper “Development of a Flight-Scale TESSERAE Habitat Concept for Biotechnology Research Outpost Applications” by Rollock, Max Pommier, William J. O’Hara, and Ekblaw, presents preliminary findings from a case study on the TESSERAE habitat which aims to bridge traditional space station architectures with future-oriented, adaptive designs. Legacy space habitats, such as the ISS, rely on monolithic hulls or cylindrical modules constrained by launch vehicle fairings, limiting scalability and geometric flexibility. TESSERAE offers a departure from these norms by using flat-packed, tile-based modules that self-assemble in orbit to form a truncated icosahedron. This structure, commonly known as a “buckyball” sharing the same shape as the carbon molecule buckminsterfullerene (C60) named after architect and inventor R. Buckminster Fuller due to its resemblance to his geodesic dome designs, will enable larger volumes and novel configurations when connected together.

The authors provide more detail on the concept referencing a trade study presented at ICES 2023 by the Aurelia Institute, which reviewed historical and contemporary space architecture to identify gaps and opportunities. They underscore the need for habitats that are both innovative and grounded in proven engineering principles. The paper serves as a “dynamic snapshot” of the ongoing TESSERAE case study as of spring 2024, inviting collaboration rather than presenting a finalized design. It envisions a platform based on TESSERAE as a commercial biotechnology research outpost in Low Earth Orbit (LEO), aligning with NASA’s Commercial LEO Destinations (CLD) goals and the burgeoning market for microgravity-enabled research. The paper highlights subsystem analyses for environmental control, thermal management, and power, alongside novel interior layouts informed by user research and terrestrial architecture best practices.

The authors make the case that self-assembling structures like TESSERAE could revolutionize human spaceflight by enabling adaptive environments that support diverse crews, including non-professional astronauts. This is particularly timely as the ISS nears decommissioning in 2031, necessitating new orbital platforms for critical research with increasing involvement by private industry..

The mission overview lays out one possible operational vision for the 2030s: a TESSERAE microgravity platform sustaining human life, scientific inquiry with a biotechnology focus, and ancillary activities in LEO. Designed for a crew of four—two biotechnologists and two career astronauts—it features biotechnology applications, capitalizing on microgravity’s unique properties for protein crystallization and biologic medicines production.

Protein crystal growth in space yields superior quality due to reduced sedimentation and convection, facilitating precise structural data for drug discovery. The paper references applications in treating among other maladies, muscular dystrophy, breast cancer, and periodontal disease, citing decades of ISS-based experiments by pharmaceutical firms. Similarly, biologic medicines—proteins, enzymes, nucleic acids, and antibodies derived from natural sources—benefit from low-gravity acceleration in discovery and preclinical testing. The global biologics market is projected to reach over $700 billion by 2030, underscoring the potential economic upside. Innovations like Redwire’s seed-based crystal manufacturing and Varda’s in-orbit ritonavir production (an HIV antiviral) have demonstrated feasibility, with microgravity enabling bulk-free returns via seeds or small samples.

The concept of operations (ConOps) details a 32-tile assembly (20 hexagons, 12 pentagons, each 2.26 m edge length, 0.46 m thick), launched in a dispenser stacked aboard a SpaceX Falcon 9 launch vehicle. After dispensing out of the payload bay, orbital self-assembly employs electro-permanent magnets for bonding at the tile edges, forming a 493 m³ pressurized volume post-clamping and gasketing. Outfitting prioritizes autonomy: critical systems integrate into the tiles, with secondary elements (e.g., storage, mobility aids) added via robotics or minimal EVAs. After full systems checkout post-assembly, operations include 1–6 month crewed expeditions, cargo resupplies, and uncrewed intervals.

Comparative occupancy analysis positions TESSERAE favorably: at 123 m³ per person, it rivals the ISS (168 m³ for six) and Tiangong (113 m³ for three) emphasizing permanent quarters and lab space for its four-person upper limit, ensuring psychological and functional adequacy. This aligns with NASA’s CLD objectives, fostering commercial viability while accommodating “visiting scientists” alongside professionals.

With respect to interior concepts and design principles, TESSERAE’s non-cylindrical, open-central geometry introduces unique interior challenges and opportunities, diverging from conventional axial modules. The paper explores layouts tailored for diverse crews, drawing on user interviews (astronauts, analogue astronauts, scientists) and literature like Sharma et al.’s Astronaut Ethnography Project and Häuplik-Meusburger’s activity-based approach. Five core design principles and “desirements” guide this strategy: a human-centered approach accounting for bodily navigation and psychosocial needs; contextual affordances leveraging microgravity (e.g., multi-axis movement in open volumes); sensory mediation via lighting, acoustics, and airflow for zoned activities; accessibility with ample, clutter-free stowage; and a balance of permanence (fixed volumes) with flexibility (reconfigurable elements like folding partitions).

These principles inform environmental mediations for biotechnology: labs require vibration isolation and containment for experiments, while communal spaces mitigate isolation via views and biophilic design elements. The paper discusses layouts prioritizing flow, orientation, and adaptability. One configuration features a central “node” for socialization and exercise, ringed by radial spokes: private quarters, labs, hygiene nodes, and utility closets embedded in the shell. This exploits the buckyball’s symmetry for efficient use of space, with tethers and handrails guiding microgravity transit. Labs allocate ~100 m³ total, segmented for crystallization (vibration-dampened gloveboxes) and biologics (flow benches, incubators), in accordance with preliminary user needs.

Diagram (Figure 5 from paper) depicting four internal layout options, with key space dividers and elevation maps depicting the arrangement of functional areas on each external tile. Credits: Annika E. Rollock et al. / Aurelia Institute
Exploded view (Figure 6 from paper) of the Lofted layout option for the TESSERAE habitat. Credits: Annika E. Rollock et al. / Aurelia Institute

Sensory design mitigates monotony: variable LED lighting simulates diurnal cycles, acoustic panels dampen noise, and materiality ( e.g., fabric panels) enhances tactility. Stowage integrates nets and modular racks, addressing chronic ISS issues. Flexibility allows crew reconfiguration via magnetic mounts, supporting mission evolution. Hygiene and galley zones emphasize efficiency, with water-efficient fixtures tied to the Environmental Control and Life Support System (ECLSS). Overall, interiors blend spacecraft rigor with architectural humanism, fostering well-being for non-experts.

The authors provide a subsystem analysis discussing trades for ECLSS, thermal control, and power. ECLSS recommendations draw from ISS heritage leveraging NASA’s Carbon Dioxide Removal and Oxygen Generation Assemblies but adapt to TESSERAE’s modularity: distributed nodes per each individual tile reduce single-point failures, with regenerative loops for water and air.

Thermal management addresses the buckyball’s high surface-area-to-volume ratio, prone to radiative losses. Multi-layer insulation and variable-emittance coatings are proposed, integrated into tiles for passive control, supplemented by active radiators and heat exchangers. Finite element modeling was used to inform stress distribution across the tile seams.

Power generation leverages roll-out solar arrays deployed post-assembly, sized for 20–30 kW demands for the needs of the labs, ECLSS and other power systems. Trades evaluate photovoltaics vs. emerging tech, prioritizing launch mass. Batteries buffer eclipse periods, with guidance navigation integrated with attitude control via control gyroscopes, minimizing propellant use.

These analyses emphasize scalability: TESSERAE’s tiles enable redundant, upgradable subsystems, contrasting with legacy monolithic designs.

The paper identifies a few challenges. For instance, assembly reliability (magnet actuation in vacuum), pressurization integrity at seams, and outfitting logistics. But opportunities abound in biotech such as enabling “fly-your-own-experiment” for scientists, accelerating drug pipelines, and demonstrating adaptive habitats for lunar/Mars precursors. User research highlights psychosocial needs—privacy amid openness, sensory variety against confinement—which will inform iterative designs.

Future work matures hardware testing in microgravity (e.g., parabolic flights), refines trades via modeling, and pursues partnerships for CLD certification. The authors invite input, positioning TESSERAE as a collaborative pivot toward reconfigurable space living.

This case study encapsulates one of TESSERAE’s promises: a self-assembling, biotech-focused habitat merging innovation with pragmatism. By the 2030s, it could sustain crews in 493 m³ of adaptive volume in LEO, tapping into a $700B+ market while advancing human-centered space architecture. Preliminary insights from this work — from ConOps to design of interiors— lay the groundwork for transformative outposts that not only return benefits to human lives on Earth, but are preparing humanity to become a spacefaring species.

While the Aurelia Institute is a nonprofit organization, Ariel Ekblaw cofounded a startup called Rendezvous Robotics which aims to generate revenue building large-scale structures like antenna apertures, space solar power arrays and orbital data centers, all autonomously fabricated in space using TESSARAE. Rendezvous Robotics recently partnered with another startup called Starcloud which plans to fabricate gigawatt-scale orbital AI data centers using Ekblaw’s invention, a potentially huge new market forecasted to be just over the horizon by several tech leaders in the news recently. Blue Origin CEO Jeff Bezos just announced he’ll be leading a new AI company called Project Prometheus and says AI orbital data centers are coming in the next decade or two. Last May former Google chief executive Eric Schmidt acquired Relativity Space to put data centers in orbit. Earlier this month Elon Musk says in not more than 5 years, the lowest cost way to do AI compute, will be in space. And Mach33 Research, an investment research firm focused on the industrialization of space, predicts that orbital compute energy will be cheaper than on Earth by 2030. TESSARAE could be leveraged to assemble these space-based hyperscalers autonomously and quickly while proving out this reconfigurable technology which can be used to build large-scale adaptable habitats and other infrastructure in space for a multitude of applications. As stated on the their website,

“Aurelia is working toward geodesic dome habitats, microgravity concert halls, space cathedrals—the next generation of space architecture that will delight, inspire, and protect humanity for our future in the near, and far, reaches of space.”

Artist illustration of a habitat constructed from TESSARAE modules in Earth orbit. Credit: Aurelia Institute

Finally, in celebration of the 50th anniversary of the 1975 NASA Space Settlements: A Design Study, the Institute announced today they are sponsoring The Aurelia Institute Prize in Design for Space Urbanism. An award of up to $20,000 will granted for concepts of a functioning space station in one of three categories: A space station in LEO or at a Lagrange point; a space habitat in lunar orbit or on the surface of the Moon; or an automated industrial facility (e.g. focused on space mining, energy, biotech, etc.) in one of those locations.

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Novel design of a Mars Cycler

Above – Mars Cycler exploded section. Below – Cruise ship-sized Mars Cycler booster (left) and docking configuration (right). Credits: Offworld Industries Corp.

At the 54th International Conference on Environmental Systems held in Prague, Czechia, this past July, a paper was presented describing an innovative design of a large-scale Mars Cycler. The authors, A. Scott Howe, John Blincow, Theodore W. Hall, and Colin Leonard, make the assumption that a significant planetary migration to Mars will happen in the near future, citing Elon Musk’s often stated goal of establishing a one-million person colony on the Red Planet by 2050. The authors argue that Starship will not be a suitable transportation method for a large, non-professional clientele on what has historically been a six-month journey due to the physiological and psychological health risks of a long-duration mission (not withstanding a recent paper penned by University of Santa Barbara physics undergrad Jack Kingdon proposing two trajectories that reduce transit times to between 90 to 104 days each way).

Instead, they envision a “cruise ship” approach using a large, robotically constructed Mars Cycler that would continuously travel between Earth and Mars. The concept for a Mars Cycler was first conceived by Buzz Aldrin in a 1985 paper, and in recognition of his invention, is often referred to as an Aldrin cycler. This particular cycler design is advantageous because it would use minimal propellant to maintain its trajectory. The concept features a dual-torus structure, with a non-rotating outer torus for docking and a rotating inner torus to provide artificial gravity. The paper lays out in detail the specifications for a minimal-sized version with crew capacity of 52-61 people, and calculates the mass and equipment required for the vessel. The authors estimate that it would take 63 Starship launches (version 3) to deliver the construction materials and propellant to low Earth orbit (LEO). A scaled up larger cruise ship-sized version with a capacity of 1000 occupants would take 428 Starship version 3 launches, which is within the range of engineering possibility and certainly within the launch rate of thousands of Starships Elon Musk envisions as part of his Mars colonization plans.

The Mars Cycler would be assembled using Offworld Industries Corporation’s Sargon System, a family of new construction machines the company claims could build an entire space station in half a year (Blincow is CEO of Offworld Industries Corp). The novel construction technology autonomously assembles preformed hull panels loaded in a magazine, robotically dispensed, formed and welded into large toroidal (or other shaped) space stations ready to be pressurized.

The paper advocates for the cycler to provide artificial gravity to mitigate the deleterious health impacts of microgravity allowing occupants to maintain healthy muscle and bone density throughout the journey. The proposed design decouples an inner artificial gravity centrifuge from an outer non-rotating torus, which offers several operational benefits:

  • Distributed docking ports: The non-rotating outer torus can accommodate multiple visiting vehicles docking at various points around its perimeter.
  • Fixed systems: Solar panels and radiators can be mounted without the need for gimbals or motorized mounts, simplifying the design.
  • Seamless transfer: Crew and cargo can be transferred between visiting vehicles and the cycler without the need for spin-up or spin-down procedures.

The paper identifies several challenges to overcome in order to realize an operational Mars Cycler. The top five include:

  1. Large-scale space construction: The project requires the construction of very large orbital structures. A key challenge is maintaining tolerance control during assembly, ensuring panels fit together precisely and the torus closes properly.
  2. Attitude control and maneuvering: The paper assumes, but does not detail, that maneuvering large quarter-toroids in proximity to each other will be possible without “exotic solutions’. This is a significant challenge because each section would have its own center of mass and orbit, creating strain on connected elements.
  3. Artificial gravity implementation: A number of difficulties are discussed, including economic spin-up/spin-down, docking procedures while the structure is spinning, and performing extra-vehicular activities (EVAs) under rotation. The paper also notes that transferring power, control, information, and liquids between the rotating and non-rotating segments would be challenging.
  4. Mars surface infrastructure: The paper acknowledges that a major challenge is the “big elephant in the room of Mars surface infrastructure”. The entire concept is based on the assumption that the necessary infrastructure, such as propellant production facilities, will be in place on Mars by the time the cycler is ready.
  5. Life Support Systems: Sustaining human crews on a cycler for extended periods (e.g., months-long transits) requires robust life support systems for air, water, food, and waste management. The paper underscores the challenge of maintaining these systems with minimal resupply over multiple cycles.

Assuming these challenges could be solved, this interplanetary cruise ship design of a Mars Cycler is a new approach to deep-space travel, elegant in its simplicity. It offers a potential solution to the challenges of long-duration missions by providing artificial gravity via a rotating inner torus to ensure the health and well-being of future Mars colonists.

In addition to these cyclers providing a mode of safe space transportation, such large artificial gravity space stations could be permanently located in orbit around planets or moons that have surface communities in split life cycle space settlements which SSP covered recently. Such a facility could have duel use as an Earth-normal gravity crèche, providing birthing centers and early child development for families settling in the region. Colonists could choose to split their lives between rearing their young in healthy normal gravity settings until their offspring are young adults, then moving down to live out their lives in lower gravity surface settlements – or they may choose to live permanently in free space.

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AI networks for space settlements

Artist rendering of a robotic space farm on Mars controlled by a computer network utilizing artificial intelligence. Credits: Bryan Versteeg / Spacehabs.com

In an article in the National Space Society Space Settlement Journal, Bryce Meyer examines the integration of Artificial Intelligence (AI) into computer networks for space settlements. Meyer, an aerospace engineer, computer scientist and biologist is the founder and CEO of Cyan React, LLC, a startup that designs compact photobioreactors and provides expertise in space agriculture and life support for space habitats.

The paper describes the critical role of AI networks will play in enabling sustainable space settlements whether they be on the Moon, Mars, or in free space. These colonies, envisioned to minimize Earth resupply and achieve self-sustaining commercial operations, will face challenges due to limited human occupants (often under 100) and the absence of specialized expertise. AI systems can provide a solution that will bridge knowledge gaps, manage complex operations, and ensure rapid responses to critical issues, such as life support failures, where human reaction times may be insufficient.

The article categorizes AI into distinct families suited for space applications. Neural networks, good at pattern recognition, could help identify equipment anomalies. Generative AI (GAI), excellent at diagnostics and creative problem-solving, could propose solutions for crop failures in space farms or other equipment failures. Regression models would be leveraged for predictive analytics like forecasting resource needs.

These AI systems require robust integration with settlement infrastructure, using standard protocols like TCP/IP for communication. Training of AI agents involves learning from a pre-settlement knowledge base, periodic updates from Earth, and real-time inputs from sensors monitoring environmental conditions, equipment, and biological systems. Error management will be managed with AI outputs cross-checked by other AIs, rule-based systems, or human oversight to prevent cascading failures in critical systems.

Network architectures are key, with Local Area Networks (LANs) enabling low-latency, high-speed communication for real-time tasks like alarms and life support, while Wide Area Networks (WANs) connect settlements to external systems, such as orbital infrastructure or Earth-based servers . AI placement is strategic, positioned near action points within habitats (e.g., farms, life support systems) to minimize latency and ensure reliability in harsh extraterrestrial environments. Power constraints and radiation hardening are critical considerations for AI hardware.

The article presents a detailed scenario illustrating AI coordination in a mass flow system, as would be required in space farm. For example, crop wilting is detected by sensors, triggering a cascade of AI-driven actions: neural networks diagnose the issue, GAI suggests solutions (e.g., adjusting nutrient levels), and regression models predict outcomes. Human settlers, guided by augmented reality interfaces, validate and implement solutions, ensuring effective collaboration. The scenario underscores the need for AI to operate at multiple scales—individual plants, farm systems, and settlement-wide networks.

Bryce agreed to be interviewed via email on this enabling technology for space settlement. I am very grateful for him taking the time to dive deeper into the topic and for his detailed responses to my questions. Here is our discussion:

SSP: You mentioned that many of these AI systems are already in use in indoor farms and factories. Can you provide some examples of these instances?

BM…Not trying to pump a particular company but here are common examples:
Siemens is one of many companies that make networks of these AI enabled control systems, with control center software now: Siemens Industrial Copilot and SmartTron as well as AIRLOCK(InterLock) Systems.

Water Control: Evonik

There are also many new entry startups in this area, such as AGEYE (see below), and others, many have already tried and failed as businesses. Emerson Process is similar, with many offerings and architectures in Chemical Process Automation and Response. BASF is another with it’s xarvio® Digital Farming Solutions. Monnit makes Internet of Things (IoT) plant sensors and sensor reporting software.

It is a very active business area bridging strict rules based to AI enabled rules based and GAI systems with IoT.

SSP: In your example of an AI farm agent detecting a wilting problem with a tomato plant and coming up with a solution, you acknowledged that there are many ways in which ecosystem failures could a occur in a space farm and these scenarios would have to be anticipated to train the AI systems. Has work already been started on an AI controlled farm fault tree analysis, perhaps by the entities running the indoor farms you mentioned in Item 1?

BM…Absolutely! IoT and AI are used in combination in many indoor farms now, just not all the way to the point as shown in the paper, including the ‘recreational plant’ market and for food plants.  This is in active work now by many companies, AGEYE is one company that does have integrated solutions like the farm part of the paper (or very close to it). With a little development, automated control will combine the systems in #1, with the farm systems, with more advanced and trained systems, IoT sensors and controllers, to get to the settlement level.  It will take a merger of these to get there, but we are very close. Have parts, just need to integrate to get to the vision in the paper.

SSP: Prior to implementation for safe use in a space colony, AI systems would have to be trained on a variety of settlement functions in ground-based analogs. Perdue University’s Resilient ExtraTerrestrial Habitats Institute is doing work in this area as well as the Space Analog for the Moon and Mars at the Biosphere 2 facility in Arizona, and of course MELISSA in the EU. Are you aware of any other teams in academia or government working on this now?

BM…Really miss Ray Wheeler’s et al. NASA Biomass Production Chamber, which was the right size and type, would just need updates.

South Pole research station would work well for testing these systems…in a harsh place, limited human presence.

I know Space Development Network is proposing an inflatable farm to develop this technology too, though it needs funding.

AI control for factories and indoor farming is an active corporate area and they have their own extensive facilities, including near my home in St. Louis with Bayer (formerly Monsanto), though they aren’t focused on the particulars of space, per se, yet.

China also has extensive analog labs, since they do seek to beat the USA to long term Moon and Mars settlement. They occasionally publish.

Many colleges have funded work on vertical and indoor farming, several in my home state including at [University of Missouri-St. Louis] UMSL’s planned Yield Lab.  Technical Schools like Ranken also teach and develop methods for indoor farming that could help development of these AIs. All of these facilities can be used to shake out AI systems too.

SSP: In private industry, a few companies are actively involved in developing space-based agriculture. I’ve covered one such company, Orbital Farms, which leverages Earth’s “Dark Ecosystem”, the food chain based on bacteria that are chemotrophic, i.e. deriving their energy from chemical reactions rather than photosynthesis. An example of these type of organisms are bacteria that live near volcanic sulfur vents at the bottom of the ocean. The energy inputs and material flows of these ecosystems are 100 times more efficient in water and energy use per unit volume when compared to conventional photosynthetic food production. The very same organisms can be engineered to make pharmaceuticals, plastics, and a variety of other useful complex organic compounds. Have you considered this approach to optimize mass flows and utility in space farm ecosystems?

BM…Of course. I have considered bioreactors, both photobioreactors and non-light based systems, for a decade. They are the Swiss Army Knife of mass balancing, though I don’t see them as primary food source except in emergencies unless 3d printing and other methods become far better in the culinary sense. Food is critical for psychology too. As is the need to see green and feel and smell plants and crops. Bioreactors have many profiles and uses on Earth now, and the dark cycle chemosynthetic systems are among these. I don’t see a lack of electrical power a problem, just my 2 cents, due to nuclear reactors or space solar power in long term settlements, so I see gardens and farms. Carbon is the problem in a mass cycle. However, the dark cycle systems would be essential for making biochemicals that are either lacking from farms and algae or needed to control the mass cycling in systems. Since we are minus the huge soil ecosystem on Earth for a long while, and may need time sensitive production, the dark cycle systems would be a must just to control the overall system. I do see those on spacecraft that have limited volume, that provide bulk calorie cycling, along with smaller plant systems.

SSP: In your example in Figure 12 of a small settlement of 10 people where the mass flows are 22kg per day to and from the farm, how big is the farm in cubic meters and what would be grown there to provide enough sustenance and oxygen for the occupants?

BM…Around 1400 square meters, 2400 cubic meters (very pessimistically) assuming a VERY diverse crop mix including a few shrimp, multiple veggies and crops like potatoes or peanuts/soy, and bioreactor array with tanks, and walking areas, with continuous crop production ad infinitem. Sounds big, but that is about the size of two three-story healthy midwestern suburban houses, very roughly. Less diverse crop sets can shrink the farm drastically, to around 25% of the size, but with less dietary diversity.

SSP: With respect to training AI systems to be “space rated”, the first iterations to be implemented off Earth will not be entirely autonomous (as you have shown in your examples) and will have humans in the loop until error rates can be reduced to some tolerable level. With the speed at which AI and robotics are progressing today, while at the same time, settlement of the Moon and Mars seems to be advancing at a snail’s pace, do you see the two technologies converging in the near future so that when permanent colonies are finally established, AI networks will be able to autonomously control most critical functions without human intervention?

BM…I never will fully trust AI for everything, and I don’t think the settlers will either, at a minimum due to cybersecurity. That said, the advances in both systems and software will continue to allow more complex settlements monitored by fewer people. Automation will really will be a core technology in expanding settlements, and starting them. Farms could be growing and operating steady state before the first long term residents arrive, and as a settlement expands, it could add modules and let AI get it started and growing before bolting it onto a smaller settlement. Some things will see robotics as repair agents. The AI technology expansion will allow for more long term optimization as well, and continue to add resiliency to the settlement.

You could see a retirement home or factory on the moon with only a few human workers to keep the settlement running, a few medical technicians that are AI assisted, and robots that fix many things without bothering the staff.

SSP: You have suggested in a previous post on SSP that space farms on Mars could be the bread basket for the outer solar system. Another space farm advocate, retired software engineer Marshall Martin, has proposed a roadmap for their implementation starting with ground based analogs, but progressing mainly to rotating free space settlements, eventually resulting in millions of farms feeding billions of people throughout the solar system. When do you think we’ll see the first prototype closed loop farm implemented in space?

BM…I want farms everywhere, grounded and floating [in free space], because I want to see Trillions of Happy, Smiling Babies everywhere.

I would bet either Artemis, a company, or China fields one in the next 35 years for sure, likely sooner, just to prove the concept. Orbital factories could drive the need as much as a lunar base, just to limit resupply, but a Mars base or space station that is beyond cis lunar space will have to have such a close[d] cycle farm as a must due to limited resupply. So, when depends on if the cost to orbit gets very cheap, and cost to [the] Moon gets cheap. Cheap lift in cislunar space would limit the need to fully recycle, but beyond that distance the case gets much stronger. If it stays expensive to [get to] the Moon, the Moon would drive the need, and the farm gets built sooner.

In his conclusion to the article Meyer holds that AI complexity must align with settlement needs, balancing sophistication with reliability. Interdisciplinary collaboration is essential to refine these systems through scenario-based testing and practical implementation. By empowering minimally trained settlers, AI networks enhance sustainability, safety, and mission success, laying a foundation for long-term human presence in space.

Meyer has his own website where he collates his research and links about closed cycle farming and other space ecology topics. He is also a NSS Space Ambassador.

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Design considerations for rotating space settlements

Illustration of a cylindrical rotating space settlement in Low Earth Orbit. Credits: Grok 3

A paper by German astrophysicist Rainer Rolffs titled Rotation of Space Habitats published last October has been uploaded to the National Space Society (NSS) Space Settlement Journal. The study aims to quantify how much structural mass is required to support both the artificial gravity and the internal pressures in various designs of a rotating habitat. It expands on previous work the author completed on energy flow in such habitats, integrating considerations of cooling, energy collection (via mirrors and photovoltaics), and the distribution of interior mass.

Habitat Geometry and Design Options
Rolffs analyzes several geometric configurations, including:
– Cylinder: A habitat rotating about its central axis, with design trade-offs between compactness and rotational stability.
– Tube: A cylindrical structure rotating perpendicular to its length, featuring rounded endcaps to ensure uniform gravity.
– Oblate Spheroid: A sphere that is flattened along the rotation axis, offering a different balance between structural mass and interior volume.
– Torus: A ring-like structure where the habitat’s thickness is a fraction of the overall rotational radius.
– Dumbbell and Dumbbell with Tube: Two-sphere configurations connected either by cables or a tube; these shapes offer flexibility in managing rotational radius and gravity distribution, especially at smaller scales.

Scaling and Habitat Sizing
The analysis scales the design by considering a constant interior volume per person, leading to a range of populations from very small (few individuals) to billions. Lower limits on habitat size are determined by constraints such as acceptable rotation rates (to maintain human comfort) and the mass needed for shielding against radiation. Upper limits are set by the challenges of maintaining co-rotation of critical components like mirrors for sunlight collection and the growing demands on structural integrity and cooling systems as size increases.

Gravity Distribution and Structural Considerations
The paper provides detailed methods to compute the gravity distribution inside the habitat by dividing the interior into floors with heights that vary inversely with gravity. Rolffs examines how the structural mass must not only counteract the centrifugal forces (to create artificial gravity) but also support the self-weight of the structure, with different methods for vertical (hanging) versus horizontal (standing) support. A “critical co-rotational radius” is introduced, beyond which certain components (like non-rotating mirrors or photovoltaics) can no longer be kept in co-rotation with the habitat without incurring prohibitive mass penalties.

Trade-Offs in Mass Budget and Optimization
Not surprisingly, shielding against radiation is identified as a dominant mass component for small habitats, while for larger habitats, the structural and cooling masses become more significant. The study shows that there exists an optimum size range—between tens of thousands and tens of millions of cubic meters of interior volume—where the payload (interior mass per person) dominates the overall mass budget, and the design can be optimized for cost and functionality. Rolffs finds that different shapes yield different trade-offs; for example, the dumbbell shape is preferable at smaller sizes due to its flexible rotational radius, whereas spheroidal shapes may offer lower structural mass for very large habitats.

Detailed Derivations and Appendices
The work includes extensive mathematical derivations provided in three appendices:
– Appendix A: Details the geometric parameters and derivations for determining the rotational radius and interior volume for each habitat shape.
– Appendix B: Focuses on the gravity distribution within the habitat, explaining how the artificial gravity varies across different floors and regions.
– Appendix C: Deals with structural integrity, deriving the requirements for supporting both the artificial gravity forces and the habitat’s own self-weight, including considerations for both vertical and horizontal support systems.

Rolffs’ analysis provides design guidelines that are critical for planning future space settlements, especially in the context of reducing launch costs and using in-situ resources (e.g., processed asteroid matter) for construction. He concludes that while very large habitats are theoretically possible (even accommodating populations in the billions), practical constraints related to cooling, light distribution, and structural integrity likely favor habitats in the medium-size range with optimized shapes such as the dumbbell or oblate spheroid.

Overall, Rolffs provides an in-depth exploration of the physical and engineering challenges associated with rotating space habitats, providing both theoretical foundations and practical design criteria that could inform future developments in space settlement engineering, earning the top spot on SSP’s Artificial Gravity Section as of this post.

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Split life cycle approach to settling the solar system

Left: Artist impression of the inside of Kalpana One, a free space settlement providing artificial gravity. Credits: Bryan Veerseeg / Spacehabs.com; Right: Conceptual illustration of a colony on the surface of Mars. Credits: SpaceX.

Until recently, space settlement advocates have typically split into two camps: those who favor building colonies on the surfaces of the Moon or Mars, and those who prefer constructing O’Neill cylinders in free space, spinning to provide artificial gravity outside of planetary gravity wells. Readers of this blog know I lean toward the latter, mainly because colonies on worlds with gravity lower than Earth’s could pose problems for human physiology, particularly reproduction. Truthfully, we won’t know if humans can reproduce in less than 1g until we conduct long-term mammalian reproduction experiments under those conditions. It would be far cheaper and quicker to perform these experiments in Low Earth Orbit (LEO) rather than waiting for sufficient infrastructure to be established on the Moon or Mars for biological research.

Another approach involves not sending humans into space at all, instead entrusting space colonization to human-level artificial general intelligence (HL-AGI) and conscious machines—a non-biological strategy. With recent advancements in AGI and automation, conscious HL-AGI robots may become feasible in the near future (though the exact timeline—whether decades or longer—remains a matter of debate). This prospect might disappoint many space advocates who view migration beyond Earth as the next phase of natural biological evolution hopefully starting within our lifetimes. Deploying sentient machines would effectively remove humanity from the equation altogether.

If you’ve been following space colonization in the press you’ve most likely heard of the book A City on Mars by Kelly and Matt Weinersmith. I have not purchased the book but I’ve read several reviews and heard the authors interviewed by Dr. David Livingston on The Space Show to get an understanding of the Wienersmith’s overall viewpoint, which is at the very least skeptical, and to some space advocates downright anti-settlement. The book is very pessimistic taking the position that the science and engineering of space settlements for large populations of people is too challenging to be realized in the near future.

Peter Hague, an astrophysicist in the UK, wrote an excellent three part review setting the record straight correcting some of the critical facts that the Wienersmith’s get wrong. But in my opinion the best critique by far was written by Dale Skran, Chief Operating Officer & Senior Vice President of the National Space Society (NSS). In a recent post on the NSS blog, he links to a 90 page Critique of “A City on Mars” and Other Writings Opposing Space Settlement in the Space Settlement Journal where he provides a chapter-by-chapter, section-by-section response to the entire book as well as rebuttals to a few other naysayer publications [“Dark Skies” (2021) by Daniel Deudney; “Why We’ll Never Live in Space” (2023) in Scientific American by Sarah Scholes; “The Case against Space” (1997) by Gary Westfahl].

However, Skran credits the Weinersmiths with an innovative idea he hadn’t encountered before, one that addresses the challenge of human reproduction in low gravity. They suggest establishing orbital spin-gravity birthing centers above surface colonies on the Moon or Mars, where children would be born and raised in an artificial gravity environment—essentially a cosmic crèche. Skran builds on this concept, proposing that the life cycle of Moon or Mars colonists could be divided into phases. The first phase would take place in space, aboard rotating settlements with Earth-normal gravity, where couples would conceive, bear children, and raise them to a level of physical maturity—likely early adulthood—determined by prior research. Afterward, some individuals might opt to relocate to the low-gravity surfaces of these worlds. There, surface settlements would focus on various activities, including operations to extract and process resources for building additional settlements.

Skran elaborated on this split life cycle concept and outlined a roadmap for implementing it to settle low-gravity worlds across the solar system during a presentation at the 2024 International Space Development Conference. He granted me permission to share his vision from that presentation and emphasized that the opinions expressed in his talk were his own and did not reflect an official position or statement from the NSS.

Taking a step back, the presentation summarized research that has been performed to date on mammalian physiology in lower gravity, e.g. studies SSP covered previously on mice by JAXA aboard the ISS in microgravity and in the Kibo centrifuge at 1/6g Moon levels. The bottom line is that studies show some level of gravity less then 1g (artificial or otherwise) may be beneficial to a certain degree but microgravity is a horrible show stopper and much more research is needed in lower gravity on the entire reproduction process, from conception through gestation, birth and early organism development to adulthood. The question of reproduction in less then 1g is the elephant in the space station living room. In my presentation at ISDC last year, I took the position that the artificial gravity prescription for reproduction could impact the long term strategy for where to establish biologically self-sustaining space settlements leading to a fork in the road: a choice between O’Neill’s vision of free space rotating settlements vs. lower gravity surface colonies (because outside of the Earth all other solar system worlds where it is practical to establish surface settlements have less then 1g – e.g. the Moon, Mars, Asteroids and the moons of the outer planets – I exclude cloud settlements in Venus’s atmosphere as not realistic). I’ve been swayed by Skran’s proposal and have come to the realization that we don’t need to be faced with a choice between surface settlements or free space artificial gravity habitats – we can and should do both with this split life cycle approach.

How would Skran’s plan for settling the solar system work? He suggests we start small with rotating space settlements in LEO like Kalpana Two, an approach first conceived by Al Globus and popularized in his book coauthored by Tom Marotta The High Frontier: an Easier Way. Locating the habitats in LEO leverages the Earth’s protective magnetic field, shielding the occupants from radiation caused by solar particle events. This significantly reduces their mass and therefore costs because heavy radiation shielding does not need to be launched into orbit. In addition, the smaller size simplifies construction and enables an incremental approach. Kasper Kubica came up with a real estate marketing plan for Kalpana in his Spacelife Direct scenario.

Skran promoted a different design which won the Grand Prize of the NSS O’Neill Space Settlement Contest, Project Nova 2. The novel space station, conceived by a team of high school students at Tudor Vianu National High School of Computer Science, Bucharest Romania, slightly resembles Space Station V from the film 2001: A Space Odyssey. Many other designs are possible.

Project Nova 2 rotating space settlement, one possible design of a rotating space settlement initially built in LEO then moved out to the Moon and beyond. Credit: Tudor Vianu National High School Research Centre Team / NSS O’Neill Space Settlement Contest 2024 Grand Prize Winner

But to get there from here, we have to start even smaller and begin to understand the physics of spin gravity in space. To get things rolling Kasper Kupica has priced out Platform 0, a $16M minimum viable product artificial gravity facility that could be an early starting point for basic research.

Conceptual illustration of Platform 0, a habitable artificial gravity minimum viable product. Credits: Platform 0 – Kasper Kubica / Earth image – Inspiration4

These designs for space habitats will evolve from efforts already underway by private space station companies like Vast, Above, Axiom Space, Blue Origin (with partner Sierra Space) and others. Vast, which has for years had AG space stations on its product roadmap, recently revealed plans to use its orbital space station Haven-1 to be launched in 2026 to study 1/6g Moon level AG in a few years, albeit without crew. And of course let’s not forget last month’s post which featured near term tests proposed by Joe Carroll that could be carried out now using a SpaceX Falcon 9 as an orbital laboratory where researchers could study human adaptation to AG.

Illustration depicting a SpaceX Crew Dragon spacecraft tethered to a Falcon 9 second stage which could be spun up (in direction of down arrow) to test centrifugal force artificial gravity. Credit: Joe Carroll

Back the plan – once the rotating space habitat technology has been proven in LEO, a second and third settlement would be built near the Moon where lunar materials can be utilized to add radiation shielding needed for deep space. The first of these facilities becomes a factory to build more settlements. The second one becomes a cycler, the brilliant idea invented by Buzz Aldrin, initially cycling back and forth in the Earth Moon system providing transportation in the burgeoning cislunar economy just around the corner. The next step would be to fabricate three more copies of the final design. Two would be designated as cyclers between the Earth and Mars. Building at least two makes sense to establish an interplanetary railroad that provides transportation back and forth on a more frequent basis then just building one unit.

Here’s the crown jewel: the third settlement will remain in orbit around Mars as an Earth normal gravity crèche, providing birthing centers and early child development for families settling in the region. Colonists can choose to split their lives between rearing their young in healthy 1g habitats until their offspring are young adults then moving down to live out their lives in settlements on the surface of Mars – or they may choose to live permanently in free space.

This approach enhances the likelihood that settlements on the Moon or Mars will succeed. The presence of an orbiting crèche significantly reduces the risks associated with establishing surface communities by providing an orbital station that can support ground settlements and offer a 1g safe haven to where colonists can retreat if something goes wrong. This alleviates the pressure on initial small crews on the surface, meaning they wouldn’t have to rely solely on themselves to ensure their survival. Finally, an incremental strategy, involving a series of gradual steps with technology readiness proven at each stage through increasingly larger iterations of orbital settlements, offers a greater chance of success.

The final step in this vision for humanity to become a truly spacefaring civilization is to rinse and repeat, i.e. cookie cutter duplication and dispersal of these space stations far and wide to the many worlds beyond Mars with abundant resources and settlement potential. There’s no need to choose between strategies focused solely on surface communities versus spin-gravity colonies in free space. We can pursue both, as they will complement each other, providing families with split life cycle settlement options to have and raise healthy children while tapping the vast resources of the solar system.

Images of resource rich lower gravity worlds beyond Mars with potential for split life cycle settlement (not to scale). Top: the asteroid Ceres. Middle: Jupiter’s Moons, from left to right, Io, Europa, Ganymede, and Callisto. Bottom left: Saturn’s moon Titan. Bottom right: Neptune’s moon Triton. Credits: NASA.
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A potpourri of artificial gravity topics

Conceptual illustration of three stages in the construction of an Artificial Gravity Orbital Station (AGOS), envisioned to be a potential replacement for the International Space Station. Credits: Werner Grandl and Clemens Böck

In this month’s post we explore a few concepts and challenges related to artificial gravity (AG) that when explored and understood will enable human’s to live healthy lives and thrive in space. First up, Austria-based architect and civil engineer Werner Grandl, a researcher of space stations and space colonies, and mechanical engineer Clemens Böck describe their concept for the evolving construction of a spinning Artificial Gravity Orbital Station (AGOS) in this Research Gate working paper. AGOS is envisioned as a potential successor to the International Space Station (ISS).

The primary aim of AGOS is to mitigate the adverse health effects of microgravity on humans by providing AG. This includes preventing bone density loss, muscle atrophy, and other physiological issues associated with long-duration spaceflight (more on this later). The station would also serve as a platform for scientific research under varying gravity conditions, potentially including zero-gravity, Mars-like gravity (0.38g), and Earth-like gravity.

AGOS is proposed as a modular, rotating space station with an initial stage composed of four living modules for a crew of 24 and four zero-gravity central modules. The station is designed to be 78 meters in length, span 102 meters, have a rotation radius of 40 meters and rotate at 4.2 rpm to provide approximately 0.9g of AG for comfortable living conditions. A non-rotating central hub would carry solar panels providing power as well as docking modules, connecting tubes, and a structural framework to maintain stability. The next stage would double the living quarter modules to eight for 48 occupants. The final configuration would finish out the station with 32 modules for 180 inhabitants.

While the ISS operates in microgravity, which is ideal for certain types of research, AGOS would provide a dual environment where both microgravity and AG conditions can be studied. This dual capability could enhance research in life sciences, materials research, and space technology development.

There are difficulties associated with the concept though, which will have to be resolved. The paper acknowledges that the engineering complexities of maintaining a rotating structure in space, ensuring stability, and dealing with the dynamics of spin gravity on the human body, especially disorientation caused by Coriolis forces, will be quite challenging to overcome.

Still, the future benefits made possible by AGOS will make overcoming these challenges worth the effort. When realized, AGOS would help enable more ambitious space exploration goals, including using the facility for human missions to Mars, where AG may be necessary and beneficial for long-term crew health during transit. It also could open avenues for commercial space ventures in Low Earth Orbit (LEO), including tourism and manufacturing under partial gravity conditions. Ultimately, AGOS could be a significant leap in space station design, enhancing both the scientific output and the prospects for human health in space for extended periods.

In a recent update on their concept penned by Grandl in ResearchOutreach, along with collaborator Adriano V. Autino, CEO of Space Renaissance International, they extend the possibility of constructing self-sustaining colonies in space via utilization of lunar and asteroid materials. Asteroids, in particular, could be hollowed out to serve as natural shields against cosmic radiation and micrometeoroids while mining for resources like metals and water.

Grandl describes a feasible design where a mined-out asteroid provides radiation shielding for a rotating toroidal habitat built inside the body for a population of 2000 people. Rotationally driven by magnetic levitation and natural lighting provided by reflected sunlight, the facility would mimic Earth gravity and environmental conditions for healthy living. This colony could sustainably support human life with integrated systems for air, water, food, and waste management.

Artistic rendition and cross sectional layout of an asteroid habitat for 2,000 colonists with a rotating torus driven by magnetic levitation while sunlight is reflected into the enclosure along the central axis illuminating the living space via a mirror cone. Credits: Werner Grandl

This approach would only work for larger solid body asteroids which are fewer in abundance and tend to be further away from Earth in the main asteroid belt. Smaller “rubble pile” bodies that are loose conglomerations of material like the Near Earth Object (NEO) Bennu recently sampled by the spacecraft OSIRIS-REx, could be utilized in an innovative concept covered a couple of years ago by SSP. The asteroid material is “bagged” with an ultralight carbon nanofiber mesh enclosure creating a cylindrical structure spun to create AG on the inner surface. Physicist and coauthor on this work Adam Frank, mentioned this approach when he recently appeared on the Lex Friedman podcast (timestamp 1:01:57) discussing (among many other space related topics) the search for life in the universe and alien civilizations that may have established space settlements throughout the galaxy and beyond (highly recommended).

A cylindrical, spin gravity space settlement constructed from asteroid rubble like that from the NEO Bennu. The regolith provides radiation shielding contained by a flexible mesh bag made of ultralight and high-strength carbon nanofibers beneath the solar panels. The structure is spun up to provide artificial gravity for people living on the inner surface. Credits: Michael Osadciw / University of Rochester

SSP has covered a scenario conceived by Dr. Jim Logan similar to Grandl’s but going big using several O’Neill Island One rotating colonies strung end-to-end in a tunnel drilled through the Martian moon Deimos.

Left: Artist impression of an Island One space settlement. Credits: Rick Guidice / NASA. Right: To scale depiction of 11 Island One space settlements strung end-to-end in a cored out tunnel through Deimos providing sea level radiation protection and Earth normal artificial gravity. Credit: Jim Logan

The authors see the creation of these permanent spin gravity settlements in space as the next step in human evolution. This vision, once considered science fiction, is grounded in realistic engineering and scientific principals.

Back to the near future, Joe Carroll addresses two topics pertinent to how AG might help mitigate deterioration of human health in space in a couple of articles in the December 9, 2024 issue of the Space Review. In the first piece, Carroll poses the provocative question “What do we need astronauts for?”, and argues that robotic spacecraft have surpassed human astronauts in space exploration due to their ability to travel farther, endure harsher conditions, and deliver more data over longer periods at lower costs. This advantage will become even greater as robotic technology and AI progress in the near future.

As an aside, for the foreseeable future there will be a debate over humans vs. machines in space. Regardless of concerns related to risks to safety, costs, and physical limitations, humans will still have the edge over robots for a while when it comes to adaptability/problem solving, complex task execution, spontaneous scientific decisions and public inspiration. A collaborative approach, leveraging the strengths of both humans and robots to achieve more efficient and effective outcomes may be better for space development in the near term.

That being said, Carroll suggests that human spaceflight activities should be focused on assessing the viability of settlements off Earth, particularly by studying human health in lunar and Martian gravity. He emphasizes the lack of data on long-term health effects in low-gravity environments and proposes the use of AG systems in LEO to simulate lunar and Martian gravity for research purposes. Carroll concludes that understanding human health in low-gravity environments is crucial for future space settlements and that humans will play a vital role in this research.

This leads into his second article which provides suggestions on how to quickly test AG in LEO. He suggests launching and deploying a long, duel dumbbell variable gravity station composed of a Crew Dragon capsule tethered to a Falcon 9 second stage that rotates to produce AG. Providing lunar gravity at one end and Martian gravity at the other, the facility would provide an on orbital laboratory where researchers could study human adaptation to these conditions. Such tests would be more cost-effective and less risky than conducting experiments directly on the Moon or Mars.

Illustration depicting a SpaceX Crew Dragon spacecraft tethered to a Falcon 9 second stage which could be spun up (in direction of down arrow) to test centrifugal force artificial gravity. Credit: Joe Carroll

But there are challenges associated with determining appropriate spin rates. This is vital as they influence the station’s radius and cost. Previous studies using vertical-axis rotating rooms on Earth have shown that higher spin rates can cause discomfort, including nausea and headaches. However, these ground-based tests may not accurately represent the sensory effects experienced in space-based AG facilities, where the spin axis is perpendicular to the direction of gravity.

This approach, on which Joe graced the pages of SSP previously, could help determine whether human settlements on the Moon or Mars are feasible and sustainable, especially when it comes to human reproduction and agriculture in lower gravity levels. Incidentally, he contributed to my piece on the impact of the human Gravity Prescription on space settlement presented last May at the International Space Development Conference 2024.

And in case you missed it, Kasper Kupica shared with SSP his Spacelife Direct approach to quickly getting started by selling AG real estate in LEO.

Implementing AG in space habitats could enhance human health and improve various aspects of space station operations (e.g. fluid flow, heat conduction, fire safety) while enabling studies of human physiology under low gravity conditions. Conducting AG tests in LEO is a prudent step toward understanding human health, determining biology related requirements for future lunar or Martian colonies and may ultimately determine the long term strategy for space settlement.