from waste to resource: what space reveals about circular design
what happens to waste in space?
For astronauts aboard the International Space Station, dealing with waste is a constant logistical challenge. Some discarded materials are collected and packed into cargo vehicles, which later burn up during reentry, while resources such as water and air are continuously recovered and reused. As missions venture farther from Earth, the ability to simply discard materials becomes increasingly limited, making the recovery and reuse of resources more important.
This makes space an interesting place to examine the circular economy. A spacecraft is a small, controlled environment in which resources are limited, resupply is expensive and storage space matters. The systems developed for these conditions are not direct solutions for cities or buildings on Earth, but they do reveal some of the practical difficulties behind the idea of keeping materials in circulation. The question here is how to design systems in which materials remain useful for longer, can be repaired or reused, and are easier to recover when they finally reach the end of their first life.
The ISS is often described as a closed environment, but it is not a completely closed material system. The station depends on regular cargo missions from Earth. Supplies arrive with food, equipment and packaging, while discarded materials are collected and stored. Some of this waste is loaded into uncrewed cargo spacecraft, which later burn up during reentry. It is a practical solution, but it depends on proximity to Earth and a functioning supply chain. A future lunar or Martian habitat will have much less flexibility.
This is why solid waste remains one of the more difficult problems in long-duration spaceflight. Food packaging, hygiene materials, textiles and other discarded items are made from different materials and are often contaminated. Simply putting them through a conventional recycling process is not straightforward.
NASA’s John F. Kennedy Space Center | image by Leejay Lockhart
turning wastewater into water and carbon dioxide to oxygen
On the ISS, the Environmental Control and Life Support System collects water from several sources, including humidity in the cabin and wastewater. Urine is processed separately, with the recovered water eventually returning to the station’s supply. The addition of the Brine Processor Assembly has allowed the system to recover more of the water that remains in the concentrated residue from urine processing. The combined system has reached recovery rates of around 98 percent, according to the research provided for this article. What is interesting here is the change in the status of the material.
On Earth, urine and wastewater are treated as waste streams in most cases, while inside a spacecraft, they are sources of water that are worth recovering because replacing that water requires sending more mass from Earth.
The system also shows that circularity requires infrastructure. Water passes through filters, distillation, treatment and other equipment, all of which consume energy and eventually require maintenance or replacement. A closed loop is therefore not a loop without inputs or losses. It is a system designed to recover as much value as possible before a resource leaves the cycle.
The same principle applies to the air inside the station. Astronauts consume oxygen and produce carbon dioxide. Life-support systems remove carbon dioxide from the cabin atmosphere, while oxygen is regenerated through water electrolysis. A Sabatier reactor can combine recovered carbon dioxide with hydrogen, producing water that can be returned to the oxygen-generation process. The chemistry is useful, but it is not completely closed. Methane is produced as part of the reaction and can be vented. Researchers have explored additional processes that could recover more of the hydrogen and carbon from this stream. These systems illustrate a recurring problem in closed-loop design: recovering one resource does not necessarily mean recovering everything. There are always residues, energy requirements and pieces of equipment that have to be maintained.
NASA’s John F. Kennedy Space Center | image by Leejay Lockhart
MELiSSA treats waste as part of an ecosystem
Developed since 1989, ESA’s Micro-Ecological Life Support System Alternative (MELiSSA) explores how microorganisms and plants could be connected into an artificial ecosystem that recycles waste, carbon dioxide and nutrients into useful resources.
At the MELiSSA Pilot Plant at Universitat Autònoma de Barcelona, different biological processes are separated into compartments. Organic waste can be broken down by microorganisms, nitrogen compounds can be transformed, and photosynthetic organisms can use carbon dioxide while producing oxygen and biomass. Plants can then contribute food and further support the atmospheric cycle. The project is interesting for architecture because it suggests that a habitat could be understood as a collection of connected processes rather than a building with a series of separate services. Food, air, water and waste are not independent systems. They affect one another.
This way of thinking has parallels on Earth, where buildings increasingly explore greywater treatment, local food production, composting and other forms of resource recovery. The difference is that space makes the relationships much harder to ignore.
solid waste is more complicated
Water and gases can be processed relatively efficiently because their composition is known and their recovery has an obvious value. Solid waste is more difficult. A spacecraft can contain plastics, fabrics, food residue, packaging and other materials in the same waste stream. Separating them requires additional labor or machinery, and contamination can make recovery harder.
NASA’s Trash Compaction and Processing System, or TCPS, is one attempt to address this problem, designed to compact and heat solid waste, removing moisture and stabilizing the remaining material. One possible use for the processed material is particularly relevant to habitat design: it can become part of the spacecraft’s protective environment. Instead of trying to turn mixed waste back into its original products, the approach gives the material another function. Circular design does not necessarily mean that a plastic package has to become another plastic package. Sometimes the more practical solution is to find a different use for the material that remains.
NASA’s Refabricator experiments explore another approach, using discarded plastic as feedstock for additive manufacturing. The system combines recycling and 3D printing so that plastic can be processed and turned into new objects such as tools or components. It is an appealing idea, particularly in an environment where bringing every replacement part from Earth is difficult. But plastics also demonstrate why the idea of infinite recycling needs to be treated with caution, as treating and processing can change the properties of polymers, while contamination and additives can make materials harder to reuse. A material may remain useful after one recycling cycle without being capable of repeating that cycle indefinitely at the same quality.
On Earth, many recycling processes involve some degree of material loss, degradation or downcycling. The important question, though, is how many useful lives the material can realistically have and what energy and infrastructure are required to give it those lives. This is where repair becomes as important as recycling. Spacecraft are designed around systems that can be maintained and replaced. In architecture, a building assembled from accessible, replaceable components is easier to adapt than one in which everything is permanently bonded together. The same applies to design. A chair that can be repaired has a different material life from one that has to be thrown away because a single component breaks. A building with dry connections can be dismantled more easily than one made from layers of inseparable materials. When resources are limited, keeping an existing object working is often more useful than finding a way to recycle it.
The Refabricator is a recycler and 3D printer in one unit about the size of a dorm room refrigerator. Pictured is the tech demonstration unit that will be tested at NASA’s Marshall Space Flight Center in Huntsville, Alabama before a flight unit is launched to the space station in April 2018. NASA/MSFC/Emmett Given
could old spacecraft become raw material?
A large amount of material already exists in orbit in the form of spent rocket stages and defunct spacecraft. Researchers and companies are exploring whether some of this material could eventually become feedstock for in-space manufacturing. CisLunar Industries, for example, has developed concepts for a Modular Space Foundry that would process metal in orbit. ThinkOrbital has explored manufacturing and welding structures in the vacuum of space. Other experiments have looked at ways of cutting and processing existing spacecraft structures without producing additional debris. These projects remain very different from an established recycling industry, and their future scale is uncertain. Their significance is nevertheless clear: once launching new material becomes difficult enough, objects already in the environment begin to look less like waste and more like material stock.
On Earth, existing buildings already contain steel, timber, glass, stone and other materials. Yet demolition often treats a building as a finished object rather than as a collection of resources that could be used again.
Mars Dune Alpha by ICON and BIG | image courtesy of ICON and BIG
mars changes the design problem
NASA’s CHAPEA program uses Mars Dune Alpha, a 3D printed habitat developed by ICON and BIG, to simulate aspects of long-duration life on Mars. The structure is an analog rather than an actual Martian settlement, but it allows researchers to examine how people might live and work within a limited environment. A real settlement would have to think carefully about every imported object. Construction materials, spare parts, packaging and equipment could not be treated in quite the same way as they are in a conventional building. This raises an architectural question: could one element perform several functions?
A wall could provide enclosure and radiation protection. Packaging could become storage or interior components. Organic waste could become a resource for growing food. Components could be designed to be repaired rather than replaced. The more isolated the habitat becomes, the more valuable these overlaps are.
the 3D printed building shows how humans could live on Mars | image courtesy of ICON
what space tells us about circular design
The most useful lesson space offers Earth is not necessarily a piece of technology we can bring back and install in our homes. A spacecraft water-recovery system, for example, is far too complex and expensive to make sense in an ordinary house. Recycling old satellites into new structures is equally difficult to imagine at the scale of a city.
What is more interesting is the thinking behind these systems. In space, water, air, food, waste and materials are closely connected because there is little room for anything to simply disappear. Components need to be maintained and repaired. Materials are kept in use for as long as possible. And when something eventually reaches the end of its first life, its next use has to be considered.
Circular design often begins with the question of what happens to a product once we no longer need it. Space suggests asking that question much earlier. How long can it last? Can it be repaired? Can its parts be separated? Could the material serve another purpose? And, when recycling is finally necessary, have we made it easy to recover?
None of these questions are particularly futuristic. In many ways, they’re all about making things that are easier to live with for longer.
Space makes the consequences more visible. On the ISS, some waste can still be packed into a departing spacecraft and sent back into the atmosphere. Water, however, is too valuable to discard. On a future lunar or Martian habitat, the same logic could extend to many more of the materials that today we would simply throw away. Space is not a blueprint for a circular economy on Earth, and many of its technologies will never make practical sense here. But the constraints of living beyond Earth offer a useful way of looking at our own systems.
NASA astronaut Jeffrey Williams, Expedition 21 flight engineer, works with the waste and hygiene compartment in the Destiny laboratory of the International Space Station | image courtesy of NASA
a sample trash tile, compressed to less than one-eighth of the original trash volume, was produced by the Heat Melt Compactor | image courtesy of NASA
This article is part of designboom’s MODES OF HABITATION chapter, exploring how the spaces we inhabit can reshape the ways we live together. Discover more stories rethinking domesticity, shared living, and the many forms a home can take here.
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