Abstract
Caves and lava tubes offer ideal environments for testing and improving methodological approaches as natural space analogs and living laboratories. These underground environments hold natural records that help us understand the evolution of our planet. This research reflects on the relevance of lava tubes and caves as simulation sites for extraterrestrial exploration. This study will focus on the methodological approach used in Lanzarote (Canary Islands, Spain) and Selvagens Islands (Madeira, Portugal), as two space analog sites associated with astrobiology projects that demonstrated good practice and reliable science and can inspire other space-related programs. Finally, the lava tube system on Terceira Island (Azores) is presented for the first time in Portugal as a promising new experimental site for geoengineering research and space analog activities. The multisectoral and longitudinal investigations related to a geoengineering approach and the 5Gs project will leverage the unique geodiversity and biodiversity of Natal Cave. Lava tube habitats could ultimately enable the establishment of a sustainable human presence on the Moon or Mars. © The Author(s), under exclusive license to Springer Nature Switzerland AG 2025.

Abstract
Objectives Space, an extreme environment, poses significant challenges to human physiology, including adverse effects on oral health (e.g., increase of periodontitis prevalence, caries, tooth sensitivity). This study investigates the differences in oral health routines and oral manifestations among analog astronauts during their daily routines and simulated space missions conducted on Earth. Materials and methods This research focused on scientist-astronaut candidates of the International Institute for Astronautical Sciences (IIAS) and analog astronauts from other institutions. The study used a cross-sectional methodology with a descriptive component. A total of 16 participants, comprising individuals aged between 21 and 55 years, were invited to complete an online questionnaire. A comparison was made between the subjects' oral hygiene practices in everyday life (designated as Earth in this research) and their oral hygiene routines during their space analog missions. Results (i) Toothbrushing duration was mostly 1-3 minutes (n = 13; 81.30% on Earth; n = 11; 68.80% on a mission); (ii) time spent was the greatest difficulty in maintaining oral hygiene routine on a mission (n = 9; 53,6%); (iii) There were more experienced oral symptoms on Earth (n = 12; 75%) than on mission (n = 7; 43.80%); (iv) The most frequent frequency of oral check-ups was > 12 months (n = 6; 37,5%); (v) Oral health materials were scarce on the mission (n = 9; 56.30%); (vi) For the majority, personal oral hygiene was classified as good (n = 9; 56.30% on Earth; n = 7; 43.80% on the mission). Conclusion and Clinical relevance This research contributes to increasing knowledge of oral hygiene measures in extreme environments, but further research is needed as this topic remains relatively understudied. This study represents an initial contribution to oral health in analog space missions, aiming to propose guidelines for future missions, including deep space missions and expeditions to extreme environments.

Abstract
The MiFiRE (Microgravity Fine Regolith Experiment) experiment, which will be launched this year on a suborbital space flight, currently scheduled for August 2023, was designed with the aim of better understanding the initial stages of planetary formation. The fundamental and embryonic question is to contribute to the study of how the mineral and rock particles, which do not have enough mass for the gravitational force to be influential, can then aggregate through electrostatic forces. In order to recreate the environment of deep space, it is assumed that the composition of meteorites that collide with the Earth, are mainly of silicate mineralogical composition or rich in metallic alloys (eg Fe-Ni). Therefore, in the experiment some fine material, identical to the lunar regolith (JSC-1), is used, in other words, amphiboles, pyroxenes, olivines and volcanic glass, along with two larger elements, a basalt cube and a metalic (siderite) meteorite cube (Octahedrite from Campo del Cielo, Argentina). It is intended that the particles be subjected to the microgravity environment and thus contribute to a better understanding of the general behaviour and the processes of preference of aggregation between the various components. This, in turn, contributes the characterization of the progressive development of planetesimals. This experiment was selected amongst 5 competing proposals in a contest launched by Massachusetts Institute of Technology's national representation, MIT Portugal, in 2020. © 2023 International Multidisciplinary Scientific Geoconference. All rights reserved.

Abstract
Volcanic sites on Earth provide valuable insights into the geological processes that shape our planet and can also serve as effective analogs for studying similar volcanic activity on other celestial bodies, such as the Moon. This work aims to discuss the general characterization of the Capelinhos volcanic site, in the archipelago of Azores in Portugal, showing the potential as a planetary analog. It's barren landscape, covered with pyroclastic rocks can lend itself the purpose of becoming a lunar planetary analog site, possibly even a Martian site. This geological site was formed during an eruption that occurred in 1957-58, thus the vegetation is practically absent. By examining the physical and chemical properties of its pyroclastic rocks, as well as the associated volcanic landforms, researchers of different fields can better understand lunar volcanic activity and its implications for many aspects of future lunar exploration. Although its origin is different from most of the locations on the lunar surface, since it doesn't contemplate the impactism originated regolith characteristics and associated geomorphology, it does resemble this setting for a broad range of research objectives. © 2023 International Multidisciplinary Scientific Geoconference. All rights reserved.

Abstract
The significance of analog studies using lava tubes on Earth to inform on the design of future lunar and Martian missions is aimed at exploring and utilising those structures as potential habitats on those planetary bodies. Lava tubes, natural subsurface cavities formed by volcanic activity, have several characteristics that make them appealing for human habitation on the Moon and Mars. Researchers conducting analog studies on Earth can gain valuable insights into the geological, environmental, engineering, crew and robotic challenges associated with lunar or Martian lava tube exploration and housing. This work reviews some scientific characteristics of an Azorean lava tube system that can contribute towards analog studies and their potential to help plan and design lunar and Martian missions. Human and robotic planetary exploration has garnered considerable attention recently, focusing on identifying potential habitats for future human missions. Lava tubes, formed by molten lava flowing beneath the solidified crust, offer natural subsurface shelters with numerous advantages for lunar or Martian habitation. This work provides insight into one of a lava tube structures, in Terceira island in the Azores archipelago. This structure would be adequate for analog studies that can contribute to the design of missions, providing valuable protocols for geological, geophysical and engineering tasks and potentially facilitating the development of sustainable lunar or Martian habitats. © 2023 International Multidisciplinary Scientific Geoconference. All rights reserved.