Rubio envisions the temple to form a part of a larger lunar base, and so the location for the would-be-building had to represent the site of a viable colony.
One of the major considerations for the placement of a moon base will be the availability of in situ resources, or more specifically, the availability of water ice. Future explorers will use this ice for a range of uses, including harvesting it to make oxygen, drinking water, and even as a component of locally-produced rocket fuel.
For this reason, Rubio selected the rim of the famous Shackleton crater as the location for his conceptual temple. Shackleton is located near the lunar south pole, where the Sun is always low in the sky, and never illuminates the depths of the 4.2-km (2.6-mile) deep crater. This patch of perennial darkness is considered the ideal place in which to find reserves of water ice.
Beyond practicality, there is a spiritual aspect to the location. More often than not, the temple would be bathed in sunlight, in stark contrast to the permanent dark of the crater below. From this location, the temple would see Earth for two out of every four weeks. Rubio believes that these aspects would come together to foster a feeling of unity, and to encourage independent thinking.
Terraced steps would lead up to the dome-shaped temple, which would feature two openings – one facing Earth, and the other, situated at the top of the structure, would afford an uninterrupted view of deep space. Three horizontal cuts located around the roof opening would allow shafts of sunlight to illuminate the interior of the temple, and in the centre of the floorspace beneath the deep space window would sit a liquid mirror telescope.
In Rubio's concept, the dome would be constructed via 3D printing, with lunar regolith being used as the chief component of the structure.
ESA is in the process of testing the viability of 3D printing with regolith on Earth, with the goal of using it as a protective outer layer to guard against micrometeorites and space radiation for lunar habitats.
Should ESA and its partners make large-scale regolith printing a reality, Rubio's temple would become a technical, if ambitious possibility. If a 50-m tall dome were to be constructed back on Earth, it would eventually collapse under its own weight. However, the low gravity environment of the lunar surface would allow the ambitious structure to endure for longer.
The lunar temple is an inspiring concept, but the reality of space exploration is a constant battle for survival against the harsh environment of space. In this setting, it is doubtful that agencies such as ESA who are looking to establish mankind's first permanent presence on the Moon will have the luxury of constructing non-essential buildings.
At least, not on the scale dreamed of by Rubio. Besides, there is the argument to be made that mankind's urge to survive and explore so desolate yet beautiful a place as the lunar surface will be nourishing enough to the human soul, without the need for augmentation.