The idea of manufacturing components directly in space is increasingly relevant to long-duration exploration. Instead of launching every replacement component from Earth, spacecraft could potentially manufacture tools, spare parts and structural components when required.

However, 3D printing in space is not simply terrestrial additive manufacturing without gravity.

Microgravity fundamentally changes heat and mass transport.

A 2026 study published in npj Microgravity investigated the thermal behaviour of photopolymers for in-space fabrication. The researchers reported that photopolymerisation generates substantial heat and that the absence of natural convection in microgravity can cause thermal accumulation. Their experiments, including International Space Station and parabolic-flight investigations, demonstrated the relationship between suppressed convective heat transfer and defects such as blistering and deformation.

This is an important engineering distinction.

On Earth, heated material can transfer energy through conduction, convection and radiation. In microgravity, buoyancy-driven convection is strongly reduced. Consequently, thermal energy can accumulate differently around the manufacturing region.

For photopolymer-based AM, this can influence curing kinetics and dimensional stability. Similar concerns arise in other manufacturing processes where heat generation and dissipation determine material behaviour.

The problem becomes even more important for autonomous manufacturing. A spacecraft cannot necessarily rely on an engineer standing beside the machine to modify parameters when defects appear.

Instead, future systems may require closed-loop manufacturing intelligence.

Sensors could monitor temperature, optical behaviour, dimensional changes and material response. Algorithms could then adjust exposure time, printing speed, cooling strategies or deposition parameters.

The system would effectively operate as:

sense → interpret → predict → modify → manufacture.

This is closely connected to NASA's broader interest in advanced manufacturing for spaceflight. NASA's Jet Propulsion Laboratory Additive Manufacturing Center works with metal and polymer AM technologies for spaceflight hardware and investigates multifunctional materials, thermal management, lattice structures and design for additive manufacturing.

The scientific significance extends beyond space exploration.

Understanding manufacturing under reduced gravity provides an unusual experimental environment for studying heat transfer, fluid behaviour, polymerisation and solidification. Space-based manufacturing can therefore act as both a technological capability and a scientific laboratory.

In the long term, successful in-space manufacturing could change spacecraft architecture itself. Instead of designing spacecraft solely around what can survive launch and what can be transported from Earth, engineers could increasingly design missions around what can be manufactured after reaching orbit or another planetary environment.

That would transform manufacturing from an Earth-based supply-chain activity into an element of space mission infrastructure.

References:

• npj Microgravity (2026), “Modeling the thermal behavior of photopolymers for in-space fabrication.”

• NASA Jet Propulsion Laboratory, Additive Manufacturing Center.