Adaptive On- and Off-Earth Environments

Off-Earth infrastructure has fascinated humanity for decades. This gave rise to a wealth of research and development in relation to structures and systems that can support life outside our planet. Currently, efforts for sustained human presence on our moon and Mars are resurging. Therefore, it is timely to reflect on challenges and opportunities posed by current thinking relating to off-Earth design. Specifically, this chapter focuses on large-scale infrastructure such as habitat shields and discusses their adaptability and reconfigurability. It is suggested that the extra-terrestrial setting—characterized by stringent constraints in resources, construction methods, and labour—relates to an extreme case of the on-Earth built environment. Consequently, it is proposed that vernacular methods of construction and contemporary form-finding method can benefit the off-Earth context, through their inherent material efficiency and use of local materials.

In order for off-Earth top surface structures built from regolith to protect astronauts from radiation, they need to be several metres thick. In a feasibility study, funded by the European Space Agency, Technical University Delft (TUD aka TU Delft) explored the possibility of building in empty lava tubes to create rhizomatic subsurface habitats. With this approach natural protection from radiation is achieved as well as thermal insulation because the temperature is more stable underground. It involves a swarm of autonomous mobile robots that survey the areas and mine for materials such as regolith in order to create cement-based concrete reproducible on Mars through in-situ resource utilisation (ISRU). The concrete is 3D printed by means of additive Design-to-Robotic-Production (D2RP) methods developed at TUD for on-Earth applications with the 3D printing system of industrial partner, Vertico. The printed components are assembled using a Human–Robot Interaction (HRI) supported approach. The 3D printed and HRI-supported assembled structures are structurally optimised porous material systems with increased insulation properties. In order to regulate the indoor pressurised environment a Life Support System (LSS) is integrated, which in this study is only conceptually developed. The habitat and the D2RP production system are powered by an automated kite power system and solar panels developed at TUD. The long-term goal is to develop an autarkic, automated and HRI-supported D2RP system for building autarkic habitats from locally obtained materials.

This chapter presents a review of cementless materials for 3D printing, with a specific emphasis on the utilization of volcanic ash in the context of a case study for off-Earth construction. As a highly promising alternative to traditional concrete, selected binders are investigated in relation to volcanic ash for the creation of an alternative concrete. These offer a multitude of compelling advantages, including exceptional sustainability, local availability, and minimal energy use. By opting for volcanic ash-based materials, a significant reduction in resource consumption and pollution can be achieved. The review concludes with a set of considerations aimed at addressing various critical aspects related to volcanic ash-based materials. These considerations encompass vital areas such as binder selection, printability, structural behavior, production optimization, in-situ resource utilization, and sustainability. The goal is to establish a solid foundation for the widespread application of cementless concrete by understanding materials, particularly in the context of utilizing volcanic ash, and thereby fostering a paradigm shift toward more environmentally friendly and resource-efficient construction practices.

This study investigated the feasibility of in-situ manufacturing of a functionally graded metallic-regolith multimaterial. To fabricate the gradient, digital light processing, an additive manufacturing technique, and spark plasma sintering were selected due to their compatibility with metallic-ceramic processing in a space environment. The chosen methods were initially assessed for their ability to effectively consolidate regolith alone, before progressing to sintering regolith directly onto metallic substrates. Optimised processing conditions based on the initial powder particle size, different compositions of the lunar regolith powders and sintering temperatures were identified. Experiments have successfully proven the consolidation of lunar regolith simulants first via near-net shaping with digital light processing and then spark plasma sintering at 1050 ℃ under 80 MPa. The metallic powders were fully densified at relatively low temperatures and a pressure of 50 MPa with spark plasma sintering. Furthermore, the lunar regolith and Ti₆Al₄V gradient were found to be the most promising multimaterial combination. While the current study showed that it is feasible to manufacture a functionally graded metallic-regolith, further developments of a fully optimised method have the potential to produce tailored, high-performance multimaterials in an off-earth manufacturing setting for the production of aerospace, robotic, or architectural components.

Long-term human and robotic exploration missions to the Moon, Mars and beyond, will require far higher levels of autonomy, flexibility and resilience than what is currently the case in low Earth orbit. Off-Earth manufacturing capabilities, especially ones using in situ resources, are an essential asset in this regard. They can indeed allow much more independence from Earth-based supplies and resources while enabling more audacious mission objectives. As also discussed in the chapter by Rich et al., additive manufacturing (AM) techniques are prime candidates for off-Earth applications. They allow a large variety of geometries to be produced using one single system, including complex 3D structures that cannot be achieved through conventional means. This makes them adaptable to evolving mission scenarios and unforeseen needs. In addition, they integrate readily with digital design techniques, supporting approaches such as computational design optimizations and generative design. Finally, AM allows a very efficient use of feedstock material by minimising the amount of scrap material. This is very beneficial in off-Earth scenarios where supplies are limited.

Although  technologically challenging, airborne wind energy systems have several advantages over conventional wind turbines that make them an interesting option for deployment on Mars. However, the environmental conditions on the red planet are quite different from those on Earth. The atmosphere’s density is about 100 times lower, and gravity is about one-third, which affects the tethered flight operation and harvesting performance of an airborne wind energy system. In this chapter, we investigate in how far the physics of tethered flight differs on the two planets, specifically from the perspective of airborne wind energy harvesting. The derived scaling laws provide a means to systematically adapt a specific system concept to operation on Mars using computation. Sensitivity analyses are conducted for two different sites on Mars, drawing general conclusions about the technical feasibility of using kites for harvesting wind power on the red planet.

Renewable energy for Mars habitats is of key interest for future crewed missions. However, the low solar irradiation and low atmospheric pressure on Mars pose serious challenges to exploiting these resources reliably. In this chapter, we investigate the technical feasibility of a soft-kite-based airborne wind energy system and its potential to power a subsurface Mars habitat in combination with photovoltaics and short-term electrical storage. We propose a soft kite for its high surface-to-mass ratio, compact packing volume, adaptability to the available wind resource, and, thus, high capacity factor. First, the siting of the habitat is outlined, and the wind resources are quantified in terms of the wind speed probability distribution at the operational height of the system for different seasonal periods. Then, a performance model for the pumping cycle operation is developed to compute the power curve of the airborne wind energy system. Combining this with the wind statistics, a process for predicting the electricity yield at the habitat location is developed, which is then used to size all components of the hybrid power system to meet the continuous electrical power demand of 10 kW of the envisioned habitat.