Urban Characteristics of Underground Cities and Extraterrestrial Colonies: Challenges and Opportunities

The World Bank has reported that urban areas currently accommodate over 50% of the global population, with this figure set to increase significantly over the coming decades. To cater to this influx of inhabitants, underground infrastructures must be developed within cities, creating additional space for individuals to thrive within urban environments. Concurrently, there is a growing interest in the colonization of extraterrestrial lands, made possible through advancements in space technology and exploration. In both cases, the habitable regions are confined within inhospitable environments, resulting in similarities in typical habitation structures. However, underground cities have the advantage of egress being possible within a few minutes, while the challenges of space colonization include radiation exposure, extreme temperatures, a hard vacuum environment, and a return trip to Earth of approximately a week. This paper seeks to examine the urban components, city image elements, and challenges of underground city spaces, intending to develop a framework for the urban characteristics of extraterrestrial colonies. The goal is to gain an understanding of the urban characteristics of underground cities and space architecture to develop guidelines for city development in challenging environments.