This is a 3D-Printed Steel Floor Prototype for a Lunar Habitat

In this decade, multiple space agencies and commercial space entities will be taking us back to the Moon. But unlike the Apollo Era, the goal of these programs is not “footprints and flags,” but to establish the necessary infrastructure to keep going back. In particular, NASA, the ESA, Roscosmos, and China are all planning on establishing outposts that will allow for scientific research and a sustained human presence.

The ESA is currently showcasing what its outpost will look like at the 17th annual Architecture Exhibition at the La Biennale di Venezia museum in Venice. It’s known as the International Moon Village, which was designed by the architecture firm Skidmore, Owings & Merrill (SOM) with technical support from the ESA. This same company recently unveiled a prototype of the skeletal metal component that will one day be part of the Village’s lunar habitats.

The component was built by MX3D, an Amersterdam-based 3D printing architecture and design firm specializing in Wire Arc Additive Manufacturing (WAAM). This process involves fusing metal wires with lasers to create lightweight metal objects with high structural strength. The company is renowned for creating the 3D printed metal bridge that spans the Oudezijds Achterburgwal canal in Amsterdam (shown below).

Her Majesty the Queen, Máxima opens the first 3D printed steel bridge in the city of Amsterdam. Credit: MX3D

The skeletal, smooth web pattern will be part of the flooring for each habitat that collectively makes up the ESA’s International Lunar Village. The prototype was created using a robotic 3D printer out of 308LSi stainless steel over the course of about 10 days (246 hours), measures 4.5 m (~15 ft) in diameter, and has a total mass of approximately 395 kg (over 870 lbs). As ESA Advanced Manufacturing Engineer Advenit Makaya said in a recent ESA press release:

“This is a remarkable achievement from MX3D, which further highlights the potential of this additive manufacturing technique for an increasing range of space applications. The design flexibility and the possibility to combine the printed structure with embedded monitoring systems – as demonstrated in the 3D-printed bridge in Amsterdam – are worth investigating for applications in space structures. This technique could also be considered for in-situ construction of infrastructure during sustainable exploration missions, for instance by using metallic feedstock derived from the locally available regolith.”

The floor component consists of six separate segments that were printed vertically before being welded together. When integrated with SOM’s design for a four-story semi-inflatable habitat, the 3D printed structure will be supported by three columns and covered by a series of floor panels. Unfortunately, SOM could not feature it as part of their exhibit – titled “Life Beyond Earth” – but manages to convey the scale of the lunar habitats that they are developing. Said Daniel Inocente, SOM’s Senior Designer for the study:

“The innovative floor design is supported from columns in the habitat walls, cantilevering towards the perimeter and centre. We looked at the manufacturing constraints and used our analysis to interpolate a web pattern that followed the angular limits of the 3D printing machines. The cross section and thickness was also analysed and differentiated to reduce the overall mass – with reduced thickness at the exterior/interior boundaries.”

Credit: SOM

The flooring and manufacturing process are consistent with SOM’s habitat design, which calls for four-story semi-inflatable shells that collectively make the International Lunar Village. Each semi-inflatable shell structure measures four stories high and offers the highest possible volume to mass ratio. Once inflated on the lunar surface, each of these habitats will approximately double its original internal volume.

The module’s inflatable design allows it to be compressed for the sake of transport and then inflated to its full size once it is deployed to the lunar surface. But unlike previous inflatable designs, where the structural and mechanical systems are typically at the center, SOM’s design allows for an open interior that optimizes the living experience. In addition to showcasing a key component in the proposed lunar habitat, the floor element demonstrates the effectiveness of the 3D printing method involved. As Gijs van der Velden, CEO of MX3D, explained:

“This was a great opportunity to show the potential of our technology for the fabrication of lightweight metal structures together with ESA and SOM. It was a perfect project for MX3D to leverage its experience in printing topology optimised metal structures. Achieving an optimal use of material is a company goal at MX3D because – just as when designing space applications – every reduced kilo in a MX3D design is a direct win for a project’s feasibility.”

“The capabilities of MX3D demonstrate inspiring concurrence of engineering and art, and are another great example to what extent additive manufacturing has already entered our society,” added Thomas Rohr, Head of the Materials and Processes team at ESA. “For space applications, such technologies not only provide improvements in performance but can lead to unprecedented and enabling design solutions.”

The International Moon Village project is a multidisciplinary effort initiated by the ESA and developed in collaboration with Jeffrey A. Hoffman – a former NASA astronaut and a Professor of Aeronautics and Astronautics at MIT. Similarly, the project is in keeping with the theme of the Biennale Architettura 2021 – “How will we live together?” – which features 112 participants in competition from 46 countries.

The purpose of this exhibition is to promote ideas for coexistence and sustainability in response to global problems. The International Moon Village exhibit is intended to show how space-related research and solutions for space habitation have applications here on Earth. Like all plans for establishing a human presence on the Moon, the key to the design is in-situ resource utilization (ISRU) and sustainability.

For example, the ESA plans to deploy the Moon Village in the Moon’s southern polar region – aka. The South Pole-Aitken Basin. In the permanently shadowed craters that mark this region, there is abundant water ice that could be harvested and used for the sake of drinking water, irrigation, and the creation of oxygen gas and rocket fuel. In addition, power can be provided by deploying solar arrays around the crater rims, which are exposed to near-continuous daylight.

This arrangement allows for a degree of resource self-sufficiency, reducing the need for resupply missions from Earth, thus reducing overall costs. As a means of manufacturing, 3D metal printing is also incredibly efficient and wastes far less material than traditional machining. These technologies will have similar applications here at home, promoting sustainable living solutions to reduce our impact on the natural environment.

Further Reading: ESA, MX3D