Conceptual Design, Manufacturing, and Assembly of a Tall Lunar Tower

The sustained and sustainable presence on the Moon, Mars, and beyond depends on the development of core infrastructure that can enable power generation, life support, and food and water production.

The design and deployment of space systems is closely coupled to mission objectives, launch vehicle payload capacity, and environmental conditions. As the development of lunar settlements and industries such as mining advance over the coming years, there will be an increasing demand for lunar power and communication systems. Existing and proposed systems are constrained by launch vehicle mass and volume limitations. This can result in complex deployable systems with many moving parts that may be prone to failure and less payload availability for other critical supplies. The development and use of in-situ Resource Utilisation (ISRU) manufacturing practices for structural components, outfitting, solar cells, and more, is widely viewed as an important enabling technology for the expansion of exploration, settlement and industrialisation activities on the lunar surface, and their long-term viability [1, 2, 11, 13].

In this context, Foster + Partners and Branch Technology supported by NASA’s Small Business Innovation Research (SBIR) Phase I program award, developed the design for a 50m Tall Lunar Tower (TLT) at the Moon’s South Pole capable of supporting solar energy equipment. The tower’s geometry provides clear load paths for resisting vertical and lateral loads whilst minimising material use through advanced manufacturing techniques. At the same time, it is optimised for autonomous manufacturing and deployment strategies through the integration of support rail geometry that can be used by robotic platforms for vertical movement across the manufacturing, outfitting and maintenance stages of deployment. Lastly, it contributes to the reduction of thermal loading through the use of a permeable diagrid structure; thus, helping it to endure the extreme temperature fluctuations found at the Lunar South Pole. This research paper presents the conceptual design, manufacturing, and assembly of the final tower design and the demonstrators fabricated by the consortium.

The proposed site of the TLT, at 89.44^∘ S, 222^∘E, elevation of 1958m, is along the Shackleton Crater - de Gerlache Connecting Ridge, and is adopted [8]. This location falls within NASA’s Artemis 2022 candidate landing site, where the maximum solar elevation angle is approximately 2.3^∘ degrees relative to the surface, with the surface temperature ranging from 100 – 400K. The lunar synodic period of 29.53 days leads to a lunar night of 14.77 days; however, local illumination at the poles varies significantly. These site-specific extreme environmental conditions provide design constraints for the development of lunar infrastructure in the following sections.

The starting point for the design evolution was the consideration of the unique lunar environment constraints and challenges in conjunction to the adoption of advanced manufacturing methods and particularly of 3D printing technologies. These hold the promise both for maximising ISRU and material efficiency whilst allowing for geometric freedom in defining and realising the tower’s optimised form. Initially four key parameters were considered (fig. 2). That is, directionality of printing, materiality, continuity, and assembly/erection process. The resulting permutations of the design typologies were assessed based on Key Performance Indicators (KPIs) including total mass tower, construction complexity, outfitting integration, and resilience. Furthermore, the consortium developed a matrix in which several weighted parameters were evaluated in a systematic way. Preliminary designs considered several typologies such as optimised trusses, cylindrical towers, and post-tensioned systems. The final diagrid system was selected due to its geometrical versatility, process driven design, maintenance-friendly characteristics, material-efficiency, and lastly its potential to reduce thermal shocks across the structure due to its permeable form.

At the final iteration, the tower’s integrated design was developed by considering the functional, environmental, manufacturing, and operational needs of the structure, from construction through to commissioning. In particular, the geometry assumes a diagrid helical form (fig. 3) which can offer clear load paths to resist a combination of loads (vertical and lateral). Specifically, the helical geometry is the defining characteristic of the tower’s form as it defines the multi-functional track which enables, manufacturing, outfitting, and solar array deployment and maintenance in-situ. The defining dimensions of the TLT are 50m height and 1m diameter resulting in a rather slender tower ration. The computational design algorithm was developed within the Grasshopper platform of the the Rhinoceros 8 CAD software and was based on a custom-made script allowing for a completely parametric definition. This enabled the explicit control of parameters such as diagrid density and dimensions, helical track density and overhang, and structural member thickness and sizing which varied along the height of the tower.

TLT construction is intended as a precursor to human presence on the Moon and will contribute towards providing the critical power systems infrastructure required for safe, long duration human missions. During settlement expansion, when humans have begun to populate the stations, it is also desirable to limit or eliminate the construction tasks that people must perform, to reduce the need for high-risk tasks and to allow them to focus on their primary missions. Consequently, autonomous manufacturing systems will play an important role in the future of space development and exploration.

While many autonomous systems have been explored for excavation works and low-height lunar construction, the domain of autonomous tall structure construction is less explored. The NASA developed ARMADAS system [4] uses swarm robot technology to offer a modular construction system using pre-fabricated building blocks, that can rapidly scale to large structures while offering redundancy through the use of a fleet of systems. The applicability of such methods to ISRU manufacturing and diverse infrastructure typologies is an active field of research.

It is envisaged that the robot systems for our TLT will be built upon a base configuration that enables vertical travel along the tower, that can be augmented to specific roles such as 3D printing for construction, manipulation platforms for outfitting, or crane systems for solar panel lifts. At this early phase of the project, the robotic systems a developed conceptually to provide the functionality required to support the proposed manufacturing process with concepts grounded in scale-model mechanisms.

Freeform 3D printing is a methodology of additive manufacturing that seeks to minimize the amount of material consumed. This is achieved by filling printed volumes with Cellular Fabrication (C-Fab®), truss-like lattices as opposed to monolithic, solid layers (e.g., FDM). The process relies on geometry to create strength - shaping structurally efficient forms similarly to how natural organisms are shaped by the forces in their environment. The result is an additive manufacturing method that consumes 95% less material compared to solid-layering. With this technique, Branch Technology has completed projects on four continents, including several of the world’s largest and most significant 3D printed structures to date: from the world’s largest-spanning 3D printed structure; the world’s largest exterior 3D printed facade; and a full-scale replica of a NASA Space Shuttle at the US Space & Rocket Center in Huntsville, AL, USA. It is the aspect of material efficiency that is in fact the most relevant benefit of C-Fab® in relation to the challenges posed by the lunar environment. This in turn also allows for structural efficiencies that can provide key benefits to NASA missions.

Material efficiency is critical to the establishment of a sustainable human presence on the Moon. This is because the necessary infrastructure will require more resources than are easily transportable or readily available. Most materials used for this purpose will need to either be launched from Earth or harvested in space. However, launching them out of Earth’s gravity well is expensive because of launch mass considerations; whereas, harvesting them in space and/or the lunar surface can be difficult. As a result, material efficiency plays a key role to sustainable lunar surface operations. In addition, the trussing lattice structures produced via freeform 3D printing can also improve structural efficiency by leveraging geometries that create a much higher strength-to-weight ratio as opposed to monolithic structures. Specifically, this structural efficiency occurs at both the micro and macro scale:

1. 1.

   At the micro-scale, only material at the cell’s boundary is utilised. This is due to the open cellular structure of the freeform lattice.

2. 2.

   At the macro-scale, structurally efficient geometries can be achieved. This is due to ability of additively manufactured designs to leverage structural optimization processes unlike other conventional methods in which the design freedom can be constrained.

In the mission to erect infrastructure such as a tall lunar tower for power and communications, construction and assembly process design can benefit from material-efficient methods that can maximize the usefulness of resources across an entire lunar outpost. Branch Technology’s C-Fab® and Freeform 3D printing techniques provide a natural inspiration for this typology as they can alleviate launch mass concerns for transported materials and quantity or difficulty concerns for lunar-harvested materials which can potentially be tailored for ISRU in the future. As a result, processes that can be informed by these techniques hold the promise for creating extensible solutions and contributing towards a permanent human presence on the Moon. In the integrated design and manufacturing approach presented here, the tall lunar tower does not comprise prescriptive, prefabricated metal truss components. It is rather 3D printed in-situ with an intrinsic truss-like lattice structure which affords wider design freedom of optimized topologies. Additionally, it seamlessly integrates outfitting capabilities and several potential future applications of the technology.

The consortium fabricated a number of demonstrators during the course of the project. These ranged from small scale 1:50 models, 3D printed at Foster + Partners London, to large scale 1:1 sections of the tower, 3D printed at Branch Technology facilities in the US (fig. 7). Specifically, a 1:50 scale model was developed as a means to evaluate the feasibility of the design, in terms of understanding the manufacturability of the tower design when using an FDM process, and the ability of a climbing model to ascend the tower using the designed-in travel rails. Additionally, the 10m-tall section of the 1:1 scale tower prototype was produced using Branch Technology’s C-Fab® process. This showcased the suitability of the tower’s design for large-scale fabrication and was exhibited at the “Earth to Space” exhibition which took place in spring 2025 at the Kennedy Space Centre at Washington DC.

This research paper presented the conceptual design, assembly, and manufacturing of a 50m tall lunar tower located at the Moon’s South Pole (fig. 6) for solar energy generation. The several aspects of the NASA-funded project were discussed including environmental constraints, integrated design, outfitting strategies, structural analysis, robotics, manufacturing, and demonstrator prototyping. Future work will focus on raising the Technology Readiness Level (TRL) of the project by further developing and testing materials, 3D printing methods, and autonomous robotic systems.