There is global space race among countries to build Moon bases, harness it’s mineral resources and helium-3, fuel for future nuclear fusion power plants. Space agencies in China, Japan, Europe, Russia, Iran , Canada and a few private companies all hope to send people to the moon by as early as 2025. They’re talking about building bases, mining for natural resources, and studying the moon in unprecedented detail. A key figure at the European Space Agency says we must look at how we exploit the moon’s resources before it is too late, as missions begin surface mapping.
As commercial space companies increase the cadence of successful rocket launches, access to space is becoming more routine for both government and commercial interests. But even with regular launches, modern rockets impose mass and volume limits on the payloads they deliver to orbit. This size constraint hinders developing and deploying large-scale, dynamic space systems that can adapt to changes in their environment or mission.
It is obviously unrealistic to use traditional launch methods for structures with large volumes (diameter greater than 15 m or size greater than 20 m, such as large space telescopes, large space habitats). In-space assembly and manufacturing can enable the construction of much larger orbital structures, for instance for setting up more sensitive radar imaging or for obtaining much higher speed of communications by assembling bigger and more sensitive antennas. It provides many other advantages such as an ability to achieve increased flexibility and resilience of spacecraft assets enabled by assembly involving additions, replacements and technology updates of payloads onto a compliant, orbiting platform. An ability to create structures that cannot be created on Earth at all because of constraints imposed by the terrestrial gravity.
Secondly the sustainable future of lunar exploration is likely to depend upon the effective use of in situ resources to generate products such as oxygen, water and other used consumables. The use of In Situ Resource Utilisation (ISRU) may provide a means of reducing the ultimate cost and risk of operation on the moon and provide a means for commercial contributions to lunar exploration. Potential products include O2 and H2O for life support or H2 and O2 for fuel and propellant (also potentially by hydrazine production from N2, NH3 and H2O2).
To address this problem, DARPA announced its Novel Orbital and Moon Manufacturing, Materials and Mass-efficient Design (NOM4D) program in Feb 2021. The effort, pronounced “NOMAD,” seeks to pioneer technologies for adaptive, off-earth manufacturing to produce large space and lunar structures.
“NOM4D’s vision is to develop foundational materials, processes, and designs needed to realize in-space manufacturing of large, precise, and resilient Defense Department systems,” said Bill Carter, program manager in DARPA’s Defense Sciences Office. “We will explore the unique advantages afforded by on-orbit manufacturing using advanced materials ferried from Earth. As an example, once we eliminate the need to survive launch, large structures such as antennas and solar panels can be substantially more weight-efficient, and potentially much more precise.
We will also explore the unique features of in-situ resources obtained from the moon’s surface as they apply to future defense missions. Manufacturing off-earth maximizes mass efficiency and at the same time could serve to enhance stability, agility, and adaptability for a variety of space systems.”
The NOM4D program will pioneer new materials and manufacturing technologies for construction on orbit and on the lunar surface as well as explore new mass-efficient designs. “People have been thinking about on-orbit manufacturing for some time, so we expect to demonstrate new materials and manufacturing technologies by the program’s end,” Carter said. “The lunar-surface focus area will be geared more towards trade studies and targeted demonstrations.” Concerning mass-efficient designs, the vision is for completely new concepts that could only be manufactured in space.
Some of the lunar manufacturing technologies DARPA wants to hear about include large, high precision mechanical structures; large solar arrays; large radio frequency reflector antennas, and segmented infrared reflective optics.
“We’re looking for proposers to come up with system designs that are so mass-efficient that they can only be built off-earth, and with features that enable them to withstand maneuvers, eclipses, damage, and thermal cycles typical of space and lunar environments,” Carter said. “Given the constraints of ground test, launch and deployment, the traditional approach to designing space structures is not likely to result in dramatic improvements in mass efficiency. In order to take the next step, we’ve got to go about materials, manufacturing, and design in a completely new way.”
The program is divided into three 18-month phases that build towards the ability to create incredibly precise, mass efficient structures from feedstock. Each phase is driven by metrics derived from increasingly challenging exemplar problems.
Phase I is considered the proof of concept for materials and designs that meet stringent structural efficiency targets using the exemplar problem of a 1-megawatt solar array.
Phase II focuses on risk reduction and technical maturation of the technology to meet structural targets, while maintaining high precision sufficient to meet the requirements of an exemplar 100m diameter RF reflector.
Phase III drives a substantial leap in precision to enable IR reflective structures suitable for use in a segmented long-wave infrared telescope. The exemplars are designed to drive metrics for each phase, and ground-based fabrication of sub-scale exemplar structures (as opposed to the full structures) will be fabricated as part of the program to validate advanced NOM4D material, manufacturing and design capabilities.
NOM4D assumes an established space ecosphere by 2030 comprising reliable logistics, facilities, and validation. This includes rapid, frequent launch with regularly scheduled lunar visits; mature robotic manipulation tools for building structures in space and routine on-orbit refueling of robotic servicing spacecraft (e.g. DARPA’s Robotic Servicing of Geosynchronous Satellites program technologies); and the availability of in-space, non-destructive evaluation methods for in-process monitoring of manufacturing and near real-time design adjustments.
DARPA’s Novel Orbital Moon Manufacturing, Materials, and Mass Efficient Design (NOM4D) program is underway with eight industry and university research teams on contract. The selected teams are tasked to provide foundational proofs of concept in materials science, manufacturing, and design technologies to enable production of future space structures on orbit without the volume constraints imposed by launch. The vision is to ferry raw materials from Earth and collect lunar materials for on-orbit manufacturing. The NOM4D program does not involve building any structures on the surface of the moon. All manufacturing would be done in orbital construction facilities and the results utilized in orbital applications.
In-space materials and manufacturing
HRL Laboratories, LLC, Malibu, California, will be developing new die-less fabrication processes to make orbital mechanical elements and bonded structures on-orbit.
University of Florida, Gainesville, Florida, will develop predictive material and correlative process models to enable on-orbit use of laser forming.
University of Illinois Urbana-Champaign, Champaign, Illinois, is working to develop a high precision in-space composite forming process utilizing self-energized frontal polymerization.
Physical Sciences, Inc., Andover, Massachusetts, will develop continuous fabrication of regolith-derived, glass-ceramic mechanical structures for use in large-scale orbital applications.
Teledyne Scientific Company, LLC, Thousand Oaks, California, will build a comprehensive materials properties database of additive-modified regolith for use in controlled thermal expansion precision orbital structures.
Mass-efficient designs for in-space manufacturing
University of Michigan, Ann Arbor, Michigan, will explore new design approaches to mass-efficient, high- precision, stable and resilient space structures based on metamaterial and metadamping concepts.
Opterus Research and Development, Inc., Loveland, Colorado, will develop designs for extreme mass efficient large-scale structures optimized for resiliency and mobility.
California Institute of Technology, Pasadena, California, will design novel tension and bending hybrid architectures and structural components with highly anisotropic mechanical response.
During Phase 1, program performers are tasked to meet stringent structural efficiency targets supporting a megawatt-class solar array. In Phase 2, teams are tasked to increase mass efficiency and demonstrate precision manufacturing for radio frequency (RF) reflectors. In the final phase, performers are tasked to demonstrate precision for infrared (IR) reflectors.
“Assuming current space technology trends continue, in 10-20 years we expect to see advances that will enable DoD to take full advantage of the NOM4D-developed technologies and capabilities,” Carter said. “This includes robotic manipulation sufficient to enable assembly of large structures from NOM4D-manufactured components, enhanced on-orbit mobility, and routine re-fueling of on-orbit assets. We also anticipate several other advantages, including more affordable space access and launch costs in LEO [low-earth orbit], GEO [geosynchronous orbit], cislunar space, and beyond.