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

Abstract
The structural assessment of submerged cathodic protection systems in Offshore Wind Turbines (OWTs) is crucial for ensuring longevity and operational efficiency. Traditional underwater inspections are expensive, inefficient, and expose human divers to hazardous conditions.This article aims to enhance the perception capabilities of underwater vehicles by introducing the Contextual Anode Locator in Varying Underwater Scenarios (CALVUS), a learning-based solution designed for the robust and precise detection of sacrificial anodes in harsh subsea environments. CALVUS leverages the feature extraction capabilities of a depth estimation ViT-based backbone to detect anode structures under challenging underwater conditions such as heavy marine snow, variable illumination, biofouling and motion blur.Evaluation on a dataset composed of images captured at the ATLANTIS Test Centre, CALVUS shows a performance of AP@50 of 97.9 %, an improvement of 19.9 % over state-of-the-art networks such as YOLO and RT-DETR. These results demonstrate the added value of using depth features during the detection operation, ultimately contributing to improved OWT operational efficiency and reduced maintenance costs. © 2025 IEEE.

Abstract
Autonomous landing for Unmanned Aerial Vehicles (UAVs) requires both precision and resilience against environmental uncertainties, capabilities that current approaches struggle to deliver. This paper presents a novel learning-based solution that combines an advanced multimodal transformer-based detector with a reinforcement learning formulation to achieve reliable autonomous landing behavior across varying scenario uncertainties. Beyond the integration of multimodality for robust target detection, this research incorporates a comprehensive analysis of the impact of state representation on decision-making performance. The proposed methodology is validated through extensive simulation studies and real-world field experiments conducted on physical UAV platforms under natural wind disturbances, demonstrating reliable transfer from simulated training environments to controlled outdoor conditions. Field experiments across varying initial conditions and wind stress confirm the system’s robustness, achieving landing precision of 0.10 ± 0.08 meters in outdoor trials, demonstrating centimeter-level accuracy that surpasses the meter-level precision of global positioning systems.

Abstract
Estuaries are dynamic ecosystems where freshwater and seawater interact, shaping complex hydrodynamic and environmental processes. Traditional single-node monitoring systems, while informative, lack the spatial resolution necessary to fully capture these dynamics. This study presents the development and deployment of a dual-node synchronized wireless sensor network for real-time environmental monitoring in the Cavado Estuary, Portugal. The network architecture integrates low-power embedded systems, a synchronized radiofrequency network, and a web-based data visualization platform. Two monitoring nodes, deployed 675 meters apart, operate in a synchronous cycle to measure hydrostatic pressure and water temperature, demonstrating the feasibility of synchronized environmental sensing. The collected data validated network synchronization, revealing a 30-minute delay in tidal propagation between nodes and highlighting temperature variations influenced by estuarine hydrodynamics. Additionally, long-term observations captured seasonal trends, tidal influences, and extreme weather events such as Storm Kirk. The study also evaluated the system's energy efficiency, confirming the solar panel's capacity to sustain continuous operation and estimating battery life expectancy under different network configurations. This work advances synchronized monitoring networks by providing a scalable, low-cost solution for studying marine environments. The proposed system enables more precise quantification of oceanic influences on estuarine conditions, particularly regarding tidal propagation and phase differences, supporting more effective ecosystem management and understanding.

Abstract
This study presents the development and testing of satellite antennas for the SONDA probe, an innovative deepsea monitoring system designed to be deployed by high-altitude balloons. The probe descends to the deep ocean, resurfaces, and transmits data while functioning as a drifter. The project faced unique design constraints, including the need for low-cost materials and lightweight construction for balloon deployment. These constraints ruled out traditional hermetic housings, necessitating alternative solutions for antenna protection. The work focused on custom ceramic patch antennas and their performance under various protective coatings, which affected the antennas' resonance and gain. Thinner layers effectively protected the antennas from high-pressure conditions and water ingress, maintaining functionality. Experiments on antenna height revealed optimal positioning above the water surface to minimize wave-induced signal interference. Hyperbaric chamber tests validated the mechanical integrity and functionality of the antennas under pressures equivalent to depths of 1500 m Antenna characterization techniques were employed in an anechoic chamber to validate antenna performance with the coating and to assess their correct operation after the hyperbaric tests. Field deployments demonstrated the antennas' capability to transmit data after diving. Challenges included communication delays, corrupted data, and mechanical vulnerabilities in materials. The findings emphasize the importance of rigorous mechanical design, material selection, and system optimization to ensure reliability in marine environments. This work advances the development of low-cost, lightweight, and modular probes for autonomous ocean monitoring, with potential applications in long-term drifter studies, real-time marine monitoring and oceanographic research.