As humanity prepares for life on the Moon and Mars, engineers are rethinking one of our oldest challenges. The circular systems being developed for space exploration could help transform how we recycle, manufacture and use resources here on Earth.
When people imagine the challenges of establishing a permanent human presence on the Moon or Mars, they tend to think first of rocket launches, radiation, extreme temperatures or the absence of water and breathable air. Yet one challenge that is often overlooked is something far more familiar: waste.
On Earth, waste can be collected, transported and recycled –– or, in some cases still, discarded. Low gravity orbit and lunar bases offer no such simple opportunity. Every kilogram launched from Earth comes at enormous financial and environmental cost, while every kilogram of waste generated during a mission consumes precious storage capacity and ultimately becomes another logistical problem requiring careful management.
For missions lasting months –– or eventually years –– waste is no longer merely an operational inconvenience. It becomes a systems engineering challenge that directly influences spacecraft design, crew safety and mission sustainability.
As humanity prepares for permanent lunar bases and eventually crewed missions to Mars, engineers are increasingly recognising that future exploration cannot depend upon a linear ‘take, make and dispose’ model. Instead, the next generation of spacecraft and planetary habitats will need to function as fully circular systems in which materials remain in continuous use.
Closing the loop in space
Recognising this challenge, the European Space Agency (ESA), through its Open Space Innovation Platform (OSIP) within the Discovery & Preparation programme, has funded a series of pioneering projects investigating how circular economy principles can support long-duration exploration.
Rather than viewing discarded materials as waste, these projects aim to transform them into valuable resources capable of supporting life, manufacturing infrastructure and reducing dependence on costly Earth-based resupply missions.
Waste from one process becomes the input for another.
Among these initiatives is the ‘Recycling, Sustainability and Circular Solutions for Future Exploration’ project led by UK technology innovation consultancy Nextek.
Founded by Professor Edward Kosior, Nextek has spent decades developing advanced recycling technologies capable of producing high-quality recycled polymers suitable for demanding applications on Earth. The ESA-funded project asks a pertinent question: can these same technologies be adapted to work in reduced gravity and eventually become part of space station and future lunar and Martian recycling systems?
Recycling without water
One of the biggest challenges is cleaning contaminated materials.
Used textiles, packaging films, polymer components and manufacturing waste cannot simply be remelted or reused if biological contamination, processing residues or degradation products remain on their surfaces.
On Earth, industrial cleaning frequently relies on large quantities of water and chemical detergents.
Neither is practical in space.
“Water is one of the most valuable resources aboard any spacecraft,” explains Professor Kosior. “Every litre has to be transported, recovered or continually recycled. Using water to wash contaminated materials is not simple under low gravity and becomes extremely difficult to justify.”
Instead, Nextek is investigating the use of supercritical carbon dioxide.
When carbon dioxide is compressed above its critical temperature and pressure, it enters a unique supercritical state, behaving simultaneously like a gas and a liquid. It diffuses through materials like a gas while dissolving oils, contaminants and many organic compounds like a liquid.
The result is an efficient cleaning medium requiring virtually no water and leaving no liquid waste stream.
For space missions, this offers several advantages.
The process could safely decontaminate polymers, textiles and manufacturing feedstocks while recovering contaminants for separate processing. After cleaning, the carbon dioxide can simply be depressurised, separating from the contaminants before being recompressed and reused in a closed loop.
Such an approach dramatically reduces both water consumption and secondary waste generation.
From rubbish to raw material
Cleaning is only one part of the equation.
The longer-term ambition is to convert used or discarded materials into feedstocks for manufacturing entirely new components.
Packaging, food containers, protective films and worn textiles all contain valuable polymers that could potentially be recovered, decontaminated and processed into filament or pellets for manufacturing systems.
Rather than launching thousands of spare parts from Earth, future crews may instead manufacture replacement components on demand. Broken tools, damaged fittings or obsolete equipment could become tomorrow’s raw material. This circular approach reduces launch mass while increasing resilience –– an essential capability when resupply missions may take months or even years.
Building sustainable lunar habitats
The importance of recycling extends well beyond plastics.
ESA’s wider portfolio of OSIP-funded research explores complementary technologies ranging from biomass conversion and biological resource recovery to construction materials derived from Martian regolith and autonomous manufacturing systems. Together they reflect a broader shift in thinking: future exploration missions must be designed as integrated circular ecosystems in which waste from one process becomes the input for another.
Every material retained within the system reduces dependence on Earth, lowers launch costs and improves mission resilience. Ultimately, sustainable space exploration will depend less on how much equipment we can transport than on how effectively we can reuse what we already have.
Space innovation benefiting Earth
Perhaps the greatest irony is that technologies developed for the harshest environments imaginable may ultimately deliver some of their greatest benefits back on Earth.
Many of the challenges facing space missions –– resource scarcity, water conservation, energy efficiency and waste reduction –– mirror those modern society are facing.
Supercritical CO₂ cleaning technologies originally investigated for lunar habitats could also help manufacturers produce higher-quality recycled plastics while using far less water. Circular material systems designed for spacecraft may accelerate more sustainable manufacturing across sectors ranging from packaging and textiles to automotive and electronics.
As Professor Kosior observes, “Space forces us to rethink waste completely. Once you leave Earth, there is no ‘away’. Everything has value because every material has already been paid for in energy, cost and launch mass.”
That philosophy may prove to be one of the most enduring legacies of the new era of space exploration. As humanity prepares to establish its first permanent footholds beyond Earth, success may ultimately depend not only on how we reach the Moon and Mars, but on how intelligently we recycle once we get there.
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Professor Kosior’s expertise in the plastics recycling sector spans 46 years, split between 23 years as an academic and 23 years working in plastic packaging recycling. He has been instrumental in designing numerous modern recycling plants and has achieved a number of patented recycling breakthroughs. In 2004 Professor Kosior founded Nextek Ltd to provide consultancy services to assist in the strategic approaches to sustainable packaging, waste reduction and minimal life cycle impact. He is involved with many industry associations, universities, and research organisations and is a Fellow of the Society of Plastics Engineering and Fellow of the Institute of Materials which awarded him the Prince Philip Medal for “Polymers in the Service of Man” in 2019. He also provides support to organisations such as the Earth Champions Foundation, Plastics Oceans, PEW Foundation Trust on the Project: Stopping Ocean Plastics.
