# Concept of a 3D-Printed Voronoi Egg-Shaped Habitat for Permanent Lunar Outpost
## 2 Principal Concepts  
### Lunar Habitat Placing Concepts  
There are four types of possible placement of the habitat on the lunar ground. Possible access to the habitat is directly associated with the type of habitat's placement (see Figure 2):  
Figure 1: An example of a Voronoi diagram in 2D dimensions. A semi-submerged habitat was built on a flat plain and its sides were secured with accumulated regolith. A significant part of it was in direct contact with the external environment and is therefore directly exposed to solar radiation and meteorites. However, it was foreseen that its structural envelope will be produced by 3D printing, which is largely made of regolith, which, together with its greater thickness, will have a certain effect on reducing these external influences. Access to the building was then solved using a 3D-printed corridor under the embankment to ensure safe and direct entry. It can also include storage areas for materials and equipment protected from the influence of radiation but was stored in a vacuum environment so as not to unnecessarily fill up the valuable interior space of the habitat. A disadvantage of this solution is the thickness of the outer printed envelope, which would have to be considerable to sufficiently reflect external influences, causing a manufacturing problem due to difficult access at higher levels above the ground. A fully submerged habitat has almost the same characteristics as the semi-submerged version. The main difference is associated with the solution to the problem of protection from the influence of the cosmic radiation. The protective layer of regolith covers the entire  
Figure 2: Concepts for placing an egg-shaped habitat on the surface of the Moon: cross-section view. (**A**) Semi-submerged, (**B**) fully submerged, (**C**) buried in a crater, (**D**) buried in a crater (levelled). habitat. As a result, it creates an additional (adequately thick) layer over the entire volume of the habitat. Subsequently, it is unnecessary to have a large thickness of the outer walls. On the other hand, erecting such a habitat will be more complicated and work-intensive. The prepared building materials would be in danger of sliding down. At the same time, the entrance corridor would have to be long to avoid possible lunar soil slides. A habitat buried in a crater is a concept working with pre-existing irregularities on the surface of the Moon, which are caused by meteorite impact. Their size varies greatly, and many have a diameter of several tens of kilometres. The idea is to gradually 3D print the habitat and pile up the regolith. The result will be flat terrain in the immediate vicinity of the habitat, with vertical access to it from the edge of the crater and vertically towards the habitat itself. The advantage of this system is no soil sliding problems, which can also fall from the edge of the crater during construction. Burying a habitat in a crater will create relatively stable conditions inside. The thick layer of regolith covering the habitat will significantly ease maintaining room temperature. The negative influence of cosmic radiation and impacts of meteorites will be significantly limited. Moreover, such habitats are likely to be used for the purpose of deep mining directly from the habitat. The disadvantage of this solution is the transport of material, equipment, and people to a less-accessible construction site. At the same time, in most cases, a huge amount of regolith will be needed for backfilling, which is also a disadvantage for future expansion of the base. Another major disadvantage is the vertical approach, which is impractical for transporting material. A buried habitat in a crater with fully levelled ground is a proposal based on the previous concept, where access to the entrance to the object is simpler. An ideal crater (regarding size and location) will be harnessed. An erected habitat will be placed in the crater. The habitat will be covered with regolith up to the level which will form an almost flat plain.