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One of the next major steps in space exploration, as noted by agencies such as NASA and SpaceX, is the creation of extraterrestrial habitats. Most current extraterrestrial habitat designs focus on above-surface solutions and do not consider all the hazards that can impact this habitat. However, the existence of lava tubes on the moon, supported by data from Gravity Recovery and Interior Laboratory (GRAIL), SELenological and ENgineering Explorer (SELENE), and NASA’s Lunar Reconnaissance Orbiter (LRO), could impact extraterrestrial habitat designs. To support life, a prospective habitat must be safe from the harsh conditions of space, including meteorite impacts, radiation, and fluctuating temperatures. Lunar lava tubes, cave-like structures created during volcanic eruptions, can house a prospective habitat. This paper provides an understanding of lava tube morphology and formation methods on Earth which gives insight into extraterrestrial lava tubes, specifically their structure, stability, and formation methods. By studying lava tubes in Hawaii, a better understanding of these qualities is formed. This knowledge provides for a more accurate model in which stability is further investigated. Several factors are investigated in this model, including size and geometry. Using a case study of the Kaumana Cave and Thurston’s lava tube in Hawaii, it is found that stable terrestrial lava tubes share many similarities with extraterrestrial lava tubes. This shows the stability of lava tubes a few kilometers wide on the Moon. By knowing more about the stability of lunar lava tubes found through this research, future extraterrestrial habitat engineering designs will be impacted.

Developing a resilient extra-terrestrial habitat with regards to long-term reliability and safety from hazards including radiation, meteorites, and quakes is necessary to ensure human survival during interplanetary exploration. The objective of this study is to examine conventional aerospace safety and reliability analysis techniques to investigate whether they are sufficient to achieve resilience in extra-terrestrial habitats. These results will be obtained to complete a strengths, weaknesses, opportunities, and threats (SWOT) analysis of compiled techniques to design a sustainable habitat system. Failure modes, effects, and criticality analysis (FMECA) and probabilistic risk assessment (PRA) with their past applications will be assessed to provide the SWOT analysis to define the requirements for a resilient analysis technique capable of measuring safety and reliability. An in-depth analysis of aerospace engineering analysis techniques will be performed for historical successes and failures and then applied to a simple case study. The research findings are intended to be used as one step toward determining the feasibility of living in other extra-terrestrial environments, including different settlement concepts in surface habitats or lunar lava tubes, by refining conventional safety and reliability analysis procedures. Techniques including FMECA and PRA can determine necessary improvements to increase safety but may lack long-term resiliency. For this reason, there is a need to merge existing risk-based techniques and other design considerations to assess long-term reliability and resilience.

In order to improve the current knowledge on structural behavior subject to extreme dynamic loading and mitigate the existing threats against civil infrastructures, embracing the new technologies in experimental evaluation of civil structures are necessary. As civil structures evolve to achieve the needs of future generations, they need to achieve more robustness and resilience under an extremely wide range of operating conditions and hazards, for their design, implementation, validation, and evaluation. Thus, civil engineers are working to develop novel smart structures that are resilient to natural hazards and demonstrate the effectiveness of performance-based design. These challenges justify the need for more experimental capabilities in evaluating structural performances in a suitable and cost-effective manner. Hybrid simulation attempts to combine the realism of shake table testing with the economy and convenience of quasi-static testing. In hybrid simulation, the structure under investigation (i.e., the reference structure) is partitioned into two substructures, (1) numerical (or analytical) substructure, which usually includes well-studied components and (2) physical (or experimental) substructure, which usually includes more complex components while the coupling between the two substructures is achieved by enforcing equilibrium and compatibility at the interface. Real-time hybrid simulation (RTHS) provides the most advanced experimental technique to evaluate the performance of rate-dependent civil structures in laboratories. In RTHS, the interface interaction between the substructures is enforced by a transfer system which includes servo-hydraulic actuator(s) and/or shake table. To implement RTHS, there is a continuous exchange of information between the cyber and physical components. Due to the dynamics of the transfer system, communication and computation delays, the feedback force signals are dependent on the system state subject to delay. In RTHS, communication delays vary from almost negligible for an RTHS using a single processor (no network) to more than a hundred milliseconds for geographically distributed testing. Geographically distributed RTHS presents a challenge in which the required communication over the Internet results in random delays. In this paper, we propose a technique to enable researchers to conduct real-time hybrid simulations at unprecedented scales of size, timing, and complexity using a series of xPC target systems. xPC target system is a real-time software environment from MathWorks enabling researchers to execute Simulink and Stateflow models on a target computer for hardware-in-the-loop (HIL) simulation, rapid control prototyping, and other real-time testing applications. Herein, a simulation tool has been developed and published on the NEEShub (nees.org), a public collaboration platform developed for earthquake engineering research. Finally, an example of a distributed RTHS will be provided in which a four-story structure will be partitioned into two numerical substructures and a physical substructure. And results of (i) a pure simulation and (ii) a distributed RTHS will be shown and the integrity of numerical models and performance of the developed simulation tool will be evaluated.