"I Patented a Space Airlock That Uses 6,000 Times Less Air": NASA Veteran Marc Cohen on Revolutionizing Space Architecture and Designing the Habitats That Will Take Humanity to Mars and Beyond

The year was 1979. While America was still celebrating the triumphs of the Apollo program, a young architect with unconventional ideas walked through the gates of NASA Ames Research Center in California's Silicon Valley. Marc Cohen wasn't there to design office buildings or mission control centers. He was there to reimagine how humans might live beyond Earth—not as visitors, but as permanent residents of space.

Over the next four decades, Cohen would challenge nearly every orthodoxy in spacecraft design. In an industry dominated by engineers who approached habitat design as an afterthought, Cohen dared to ask: What if the human experience came first? What if spacecraft were designed from the inside out?

"Engineers design machines that people have to adapt to," Cohen once remarked. "Architects design environments that adapt to people."

Now recognized as one of the founding fathers of space architecture, with multiple patents and innovations that continue to influence NASA's designs today, Cohen shares his journey through the evolution of human spaceflight and his vision for humanity's future among the stars.

The Evolution of Space Architecture

Your career spans over four decades in space architecture. How has the field evolved from your early days at NASA to now?

The field of Space Architecture has changed in two main ways. When I started at NASA Ames Research Center in 1979, the space station was the central focus of Space Architecture. Though we made minor side excursions into lunar and Mars missions, the space station remained our major objective until the early 2000s.

The landscape shifted dramatically in 2004 when President George W. Bush announced the Constellation lunar program. I took early retirement from NASA in 2005 and went to work for Northrop Grumman, focusing primarily on the Altair Lunar Lander for the Constellation program.

What surprised you most about how the field evolved during your career?

The biggest surprise came in 2010 when President Obama canceled Constellation, with the exception of the Orion Crew Exploration Vehicle—now called the Orion Multipurpose Crew Vehicle (MPCV). Adding to this surprise, Northrop Grumman laid off our entire human spaceflight engineering team following Constellation's cancellation. Orion has been operating on inadequate funding for over two decades and still has yet to fly a crew.

How have design approaches changed over the decades?

In terms of design approaches, not much has changed except perhaps there's less reliance on physical scale models and more on digital modeling. We're also seeing a significant shift with NASA no longer being the sole customer for the space exploration community. With the advent of commercial spaceflight, we're starting to see glimmers of commercial and private customers for Space Architecture.

For more on the history of space architecture as a discipline, see the AIAA Space Architecture Technical Committee publications archive at https://spacearchitect.org/pubs/pub-biblio.htm, which documents the field's evolution through conference proceedings and technical papers.

Function vs. Aesthetics in Modern Space Architecture

You've expressed concerns that some space architecture may prioritize aesthetics over functionality. How might today's space architects better balance visual appeal with practical engineering needs?

I wouldn't use the term "Modern" to describe the current state of Space Architecture, as in architecture, "Modern" refers to a specific Movement from about 1910 through the 1960s. My concern is that while the new generation of space architects demonstrate excellent skills with CAD drawings and renderings, the content of these designs hasn't improved commensurate with their presentation skills.

What criteria do you use to evaluate space architecture designs?

I evaluate Space Architecture on two sets of criteria. The first is Buckminster Fuller's Dymaxion Principle: Anticipation, Comprehensiveness, and Design as Science. Most space architects do well with Anticipation of future needs and strive for Design as Science. However, many show weakness in Comprehensiveness—taking on a hard problem and solving all aspects of it.

The second set includes five aspects of Space Architecture design: form, function, geometry, material, and structure. Most published works by newer space architects cover two or three areas well but rarely address all five consistently. The few teams that address all five aspects include SEArch+ Architects with their Mars Ice House and ICON with their large-scale 3D printing of space habitats.

What specific gaps do you see in how architects approach functionality?

Regarding functionality specifically, I view space architecture as the theory and practice of designing space living and working environments. Many space architects focus on the living environment—the habitat—but often neglect the working environment. In recent papers submitted to our AIAA Space Architecture Technical Committee, most presented beautiful renderings for habitats but included little about working environments beyond perhaps an EVA airlock. They omitted laboratories, workshops, repair facilities, and processing facilities for lunar or Martian in situ resource utilization.

For more insights on the intersection of aesthetics and functionality in space architecture, see Cohen's paper "ECLSS-First Space Habitat Architecture" (2024), which challenges conventional approaches to habitat design.  https://spacearchitect.org/pubs/ICES-2024-193.pdf 

The Impact of Commercial Space Entities

How do you see the role of commercial entities like SpaceX, Blue Origin, or Axiom Space transforming the practice of space architecture?

The upsurge in commercial space companies is beginning to transform the practice of Space Architecture, though it's not clear how far this transformation will go. Blue Origin hired space architects until their recent layoffs, but both they and SpaceX maintain considerable secrecy about their development projects.

What concerns do you have about the commercial space approach to habitat design?

Blue Origin claims to be developing the Orbital Reef space station, but we haven't seen anything new from them on this topic for over a year. Both companies restrict their employees from publishing their work, unlike Northrop Grumman where I received encouragement from management to publish.

At least four other companies are proposing to launch space stations: Axiom, Gravitics, Vast, and Voyager, but we don't see much in publications on Space Architecture from them either. My concern is that without Space Architects contributing to the total design effort, these "NewSpace" companies may not recognize and respond to the demands and nuances of the habitable space living and working environment.

What career opportunities exist for space architects in this new commercial landscape?

As for career opportunities, if companies are laying people off rather than hiring, it's difficult to identify what opportunities may exist. Getting hired as an employee or as a professional consultant remains a challenge for space architects.

For more on the emerging commercial space station ecosystem, explore the published plans for Orbital Reef, Axiom Station, and other commercial habitat concepts currently under development.

ECLSS-First Design: A Different Approach

Your work on ECLSS-First Design suggests environmental systems should drive architecture rather than the other way around. What led you to this conclusion?

What my co-authors and I wrote in the ECLSS-First Space Habitat Architecture paper is that the environmental control and life support system (ECLSS) should take precedence over any other engineering discipline for the design of the human environment.

Can you give a specific example of how this plays out in practice?

On the International Space Station, ECLSS equipment had to be jammed into spaces in equipment racks in locations that had been assigned arbitrarily by system engineers. As a result, the ECLSS installations were spread out in inefficient ways or packed together in the wrong places. The outcome was ECLSS hardware that was less efficient and harder to maintain, repair, or service than it could have been if the ECLSS installations had received more respect.

Space Architects need to learn to work with ECLSS, to anticipate it, and to accommodate it to ensure and enhance habitability in the space living and working environment.

For a comprehensive analysis of this approach, refer to Cohen et al.'s 2024 paper "ECLSS-First Space Habitat Architecture" published for the 53rd International Conference on Environmental Systems, which details the rationale and implementation of this design philosophy.

The Suitport: A Counterintuitive Design Success

Could you share a specific example where research led you to a counterintuitive design solution that ultimately proved superior to conventional approaches?

The Suitport is an excellent example of being surprised in the course of pursuing research. In the 1980s, I received funding from the Space Station Advanced Development Program for Extravehicular Activity (EVA) Architecture, specifically to design an airlock that would support and be compatible with the AX-5 space suit being developed at Ames by Hubert "Vic" Vykukal. The AX-5 spacesuit had a rear entry hatch in the torso, which proved to be a vital feature.

How did you approach this design challenge?

I had anticipation of all the needs for a space-suited astronaut transiting through an airlock. Comprehensiveness drove me to conduct a comparative analysis study of multiple airlock concepts. Design as science took me to look from first principles at the essential functions of the airlock.

The size of a conventional airlock would be on the order of four to six cubic meters. I started from the assumption that the best candidate airlock configuration would be one into which the space-suited astronaut would step, seal the hatch behind her, evacuate the air from the chamber, then open the hatch to space, and step out into vacuum.

What was the key breakthrough in your thinking?

One key issue was whether to simply sacrifice the air from the airlock or to conserve about 90 percent of it by pumping down the airlock to a holding tank. Pumping down the airlock would cost roughly 5KW of power for about an hour, plus pump cooling, and wasted crew time.

So, I had to think deeply about what it meant to displace the air in the airlock. What I realized was that from first principles, it wasn't necessary to have an airlock full of air at all. It was totally counterintuitive, but neither pumpdown nor sacrifice of all the air was necessary. I asked the question that Maimonides posed: "What is the necessary truth?"

The necessary truth was that it was only required to break the seal of the cabin atmosphere, which could be done by bleeding off the air in a small interstitial volume between the suit's rear entry hatch and the space station exit/entry hatch. This interstitial volume could be as small as a liter of air. There are 1,000 liters of air in a cubic meter. So, the Suitport air savings compared to a conventional airlock is on the order of 4,000 to 6,000 times.

How has the Suitport concept been adopted since your original patent?

Since I patented the Suitport, it has taken on a life of its own. Many space architects have incorporated Suitports into their habitat designs. Astronaut Mike Gernhardt took the lead on building the full-scale, working prototype of the Suitport into the NASA JSC lunar electric rover (LER). Other vehicles with Suitports include the Ames Hazmat Vehicle, a converted armored personnel carrier, the University of North Dakota Rover, and Pascal Lee's Arctic Rover.

For technical details on the Suitport concept, see Cohen's U.S. Patent 4,842,224, "Suitport Extra-Vehicular Access Facility" (1989) and his paper "The Suitport's Progress" (AIAA-95-1062), which documents its evolution and various applications.

How has the Suitport evolved since your original patent, and what challenges remain in its implementation for future space missions?

The evolution is multifold. Several people have built interpretations of the Suitport into habitats or pressurized rover simulators. Mike Gernhardt has worked on improving the technology. In my original concept, I drew a mechanical sealing system. Mike has adapted an inflatable seal concept borrowed from the food processing industry.

How does NASA's current approach compare to your Suitport concept?

In the meanwhile, NASA HQ has gone in a different direction in the near term. They are baselining a pressurized rover for the Moon without any airlock at all. In order for the crew to go EVA, they will need to depressurize the rover cabin. That kind of operation is a throwback to the Apollo era; they will quickly have a problem with the cabin atmosphere filling up with toxic regolith dust on the space suits.

For more on the current state of Suitport development, see NASA's Artemis program documentation on EVA systems and lunar mobility systems, which provides context on current approaches to suited operations on the lunar surface. The Popular Mechanics article shows Mike Gernhardt's Lunar Electric Rover with Suitports installed in the external driving positions, and NASA's company selections for moon mobility for Artemis missions.

Innovative Space Station Design

Looking back at projects like your Triangular-Tetrahedral space station concept, which of your innovations do you feel were most ahead of their time?

One of my colleagues from the University of Michigan, Yelena Lembersky, once told me, "Your problem is that you are always too far ahead of your time." I never felt "underappreciated." For 26 years at NASA, almost five years at Northrop Grumman, plus seven years running my own business, Astrotecture®, I was always deeply in the mix of space projects.

Which of your concepts have gained the most acceptance over time?

I feel gratified that many of my ideas have reached levels of acceptance. For example, I won a NASA Innovative and Advanced Concept (NIAC) Award for Robotic Asteroid Prospector (RAP). Even though my team couldn't win the NIAC Phase 2, the idea has lived on. Other people have picked up the idea of prospecting asteroids. Astro Forge has just launched their ODIN asteroid prospector. Joel Sercel won a NIAC for developing the solar-thermal system we proposed as part of RAP and is now trying to develop the bag we proposed to use to capture a small, water-laden asteroid.

What elements of your Triangular-Tetrahedral Space Station made it into actual space station designs?

Regarding the Triangular-Tetrahedral Space Station, one of its main features was spherical, relocatable nodes to join cylindrical modules in a triangular and tetrahedral pattern. The patent also claimed a cupola attached to a berthing port position. The spherical nodes made it into the Space Station Freedom configuration in October 1985 during the Requirements Update Review-2 (RUR-2). They stayed in the configuration until August 1986, when the nodes were turned into short cylinders. However, the new nodes still perform the same function as the original spherical nodes to join multiple modules to a common hub. And the cupola is now flying on the ISS, right where a berthing port would be.

What aspect of your design hasn't been fully understood or implemented yet?

What is not yet understood in the engineering community is the tetrahedral geometry of the space station I proposed. To create this assemblage of pressurized modules, the space station would need a different type of berthing connector. The present berthing connections are strictly linear; the berthing mechanisms align in a strictly straight line. What I proposed as necessary for any space station in which the modules form a closed loop—whether that loop is square or triangular—is a lateral attachment berthing mechanism.

For detailed technical information on the Triangular-Tetrahedral Space Station concept, reference Cohen's patent documents and NASA technical reports from the 1980s Space Station architecture studies.

You mentioned that engineers didn't fully understand your proposed lateral attachment berthing mechanism for tetrahedral geometry. What specific advantages does tetrahedral geometry offer for space stations?

The triangular and tetrahedral geometry is self-rigidizing. A triangle is the basic unit of a pin-jointed truss. A triangular pin-jointed connection does not need to transmit bending moments. A rigid rectangular right-angle joint must be strong enough to resist and transmit bending forces. That means the primary structure must be much stronger and heavier in an orthogonal connection.

Can you explain how the lateral berthing connector would work?

As for the lateral berthing connector, it's not really that complicated. The module-to-node connection lines up along the central axis, then a clamping mechanism closes from off-axis to hold the two pieces together. I built a scale model to demonstrate how it worked.

For more on structural advantages of tetrahedral geometries in space applications, see materials on tensegrity structures and space truss design principles as applied to orbital infrastructure.

Space Mining and Future Infrastructure

Regarding your work on the Robotic Asteroid Prospector, what kind of in-space infrastructure would be needed to make asteroid mining economically viable?

What I tried to explain in the final report for Robotic Asteroid Prospector was that it is not economically viable to return materials in large quantity from space mining to the Earth. Even if the cost of access to space declines to 10 percent of current costs, it will still be too expensive to return ordinary minerals or even platinum series elements to Earth and make a profit. There are space mining advocates who talk about how some asteroids may hold a 50-year world supply of platinum. If someone could return all that metal to the Earth in a short period of time, just think of what it would do to the market price.

Where do you see the real market for space mining?

What I said in that final report was that space mining will become profitable when there are paying customers IN SPACE who want and need the mined materials or products made from the ores.

For comprehensive analysis of asteroid mining economics and technical approaches, see the "Robotic Asteroid Prospector (RAP) NIAC Phase 1 Final Report," which discusses mission architecture, spacecraft design, and economic models for sustainable asteroid resource utilization.

The Future of ECLSS Systems

Could you share specific examples of ECLSS inefficiencies on the ISS that could have been avoided with your proposed ECLSS-First approach?

This is a complex question because it touches on what the ISS Environmental Control and Life Support System (ECLSS) was in its original embodiment, how it changed many times from its original conception as Space Station Freedom, and how it has been upgraded repeatedly over almost three decades.

How has ISS ECLSS performance evolved over time?

In the early days, the ISS was recycling only a comparatively small fraction of the water. The Russians and the Americans had to bring up resupplies of water and oxygen at regular intervals. Over time, the recycling of water improved through better humidity condensate and waste water reprocessing, new systems were added, resupply requirements were reduced, and now the water recycling is about 95% efficient. That would mean losing 20% of the water in a year, which is acceptable for an orbital space station but probably would not be good enough for a human Mars mission.

What specific design issues could an ECLSS-First approach have addressed?

I've discussed this with colleagues on the AIAA Life Sciences and Systems Technical Committee, and they noted several issues where an ECLSS-first approach might have created a better ISS:

• Not every module has its own life support
• Pathways for ventilation among connected modules/vehicles are limited in location and capacity
• No dedicated food production capability to date
• Reliance on EVA for initial construction when both station and suit life support were consumables-heavy
• Incompatible life support systems (e.g., silver vs iodine biocides in water treatment)

How would an ECLSS-First design approach have changed the ISS architecture?

The total redesign of ISS or another space station to be ECLSS-First might have given each module its own essential core ECLSS for thermal, pressure, gas mix, air revitalization, contamination control, and so on. The ISS design for on-orbit installable equipment racks meant that the ECLSS equipment needed to fit into tight volumes: 1.05m × 2.10m × 0.9m. The necessity of jamming this equipment into four ISS racks for the Tranquility node meant that the connections between the sections needed to be made on-orbit, which may have compromised the best way to accommodate the hardware compared to doing it in a single, continuous volume.

For technical details on ISS ECLSS systems evolution and challenges, see NASA and ESA technical reports on life support system performance, ESA ECLSS factsheets, and the AIAA Life Sciences and Systems Technical Committee publications on advanced life support architectures.

Future Paradigm Shifts and Guidance for New Space Architects

Given your 40+ year perspective, what do you believe will be the next major paradigm shift in space architecture?

I can't predict what will be the NEXT major paradigm shift in the sense that Harold Kuhn meant when he coined the term in his book "The Structure of Scientific Revolutions." I can predict the next fad in Architecture and Space Architecture: Artificial Intelligence. But I have a hard time imagining that AI will ever become a substitute for true creativity.

What would represent the ultimate paradigm shift for the field?

As for paradigm shifts, I can tell you what would be the ultimate paradigm shift for Space Architecture: space architects IN SPACE designing Space Architecture FOR SPACE.

For thought-provoking perspectives on the future of space architecture, see proceedings from recent AIAA ASCEND conferences and International Astronautical Congress (IAC) sessions on advanced concepts for space habitation.

You mentioned Fuller's Dymaxion Principle and your own five aspects of design––form, function, geometry, material, and structure. Which of these do you believe new space architects most often neglect?

It varies with each individual project. Different space architects emphasize one or more of these aspects and place less emphasis on others.

Can you give specific examples of how projects might excel in some areas while falling short in others?

For example, there are several recent projects by different space architects that focus on geometry, particularly on space-filling geometric lattices. One uses truncated octahedra, another uses rhombic dodecahedra, a third uses three-frequency modified icosahedra, otherwise known as soccer balls. I love these geometries. Each project does a splendid job of articulating the geometry, and some make stipulations about the structural strength, panels or faces, edges or struts, joints, and materials. The great challenge for a space habitat is how to make the volumes within each of those polyhedra useful as habitable living and working environments. That's where those projects may fall short.

In some other projects, there may be an excellent design for the living environment, but it may not be clear how the primary structure of the pressure vessel accommodates it. In other cases, there may be excellent primary structure, but the material may be undefined, or the functionality of the interior may be vague.

How does Fuller's principle of Comprehensiveness apply here?

That's where the Comprehensiveness of the Dymaxion Principle comes into play, covering all those bases to a credible level.

For more on Buckminster Fuller's design principles and their application to space architecture, see Fuller's writings on synergetics and comprehensive anticipatory design science, as well as Cohen's papers applying these principles to space habitat design. Additional resources include Ideas and Integrities at Open Library and the Buckminster Fuller Institute's collection.

Having worked in both traditional architecture and space architecture, what do you think terrestrial architects could learn from space architecture principles, and vice versa?

All or nearly all Space Architects started from a traditional education in terrestrial architecture. To quote James Stewart Polshek, who was Dean of the Graduate School of Architecture, Planning and Preservation at Columbia while I was a student there, ”There is a relationship between beautiful drawings and beautiful buildings.” That means that the presentation of architectural concepts has an impact on the final product. The habitable design brings visual, aural, olfactory, and tactile cues for the designed and built environment.

What specific lessons can space architecture offer to terrestrial design?

What Space Architects can teach terrestrial architects is to think of buildings as systems of systems. Closing the loops on environmental conditioning. Sustainability in terms of limiting the consumable resources needed by creating design efficiencies and regenerative environmental conditioning can serve as a touchstone for both terrestrial and space architecture.

Marc Cohen's pioneering work continues to influence how we approach the design of habitats for the future of human space exploration. His emphasis on comprehensive, functional design that prioritizes human needs while addressing the unique challenges of space environments remains a guiding principle for new generations of space architects.

About Marc Cohen

Marc M. Cohen is a licensed architect, who is a founder of the field of Space Architecture.  He retired from NASA where he worked on SpaceLab, ISS, and humans to the Moon and Mars.  He then worked for Northrop Grumman on the Constellation Lunar Program.  Next, he opened Astrotecture®, winning several NASA grants, including a NASA Innovative and Advanced Concept grants for the Robotic Asteroid Prospector and the Water Walls Life Support Architecture.  Next, joined the new Space Cooperative, with a focus on a new concept for the Antaeus Planetary Quarantine Facility to receive samples returned from Mars at the Deep Space Gateway in lunar orbit.  Now he is an independent space architect and scholar.  At this time, he is writing a book about Space Architecture.  Marc holds architecture degrees from Princeton, Columbia, and the University of Michigan.  He lives in Milford, CT, with his wife, Jane Jacobson.