European robots test lunar cave exploration ahead of Moon bases

European scientists have successfully tested a robotic system designed to explore the Moon's underground lava tubes, marking a significant step toward establishing permanent human bases on the lunar surface. The mission concept, developed by a consortium led by Germany's research center for artificial intelligence, uses three different types of robots working together to map and study these harsh underground environments. The system was tested in volcanic caves in Lanzarote, Spain, in February 2023, and researchers say it is now ready for future missions to the Moon and Mars.

Lunar lava tubes have long attracted the attention of space agencies because of their potential to protect astronauts. These underground tunnels offer natural shielding from cosmic radiation and micrometeorites, hazards that pose serious risks to humans on the lunar surface. The tubes could also provide access to water ice and other resources buried beneath the Moon's surface, making them valuable locations for long-term exploration and habitation.

Background

The Moon's lava tubes are remnants of ancient volcanic activity. Over billions of years, flowing lava carved out tunnels beneath the surface, and many of these tunnels later collapsed, creating pits and caves that are visible from orbit. Scientists have identified these features as potential sites for future human missions, but reaching and studying them presents enormous technical challenges. The terrain around cave entrances is rough and unstable, entry points are limited, and the underground environment is dangerous and difficult to navigate.

The European Space Agency has been actively pursuing research into lunar cave exploration for several years. In recent calls for proposals, the agency asked for creative ideas on how to design robotic missions that could safely enter these caves, map their interiors, and gather scientific data. The goal is to develop technologies that will eventually allow human explorers to use these natural structures as shelters during extended stays on the Moon.

"Exploring and mapping these tubes could provide new information about the moon's geology, but they could also be an interesting option as long-term shelter for future human visitors to the moon. They would shield astronauts from cosmic radiation and micrometeorites and possibly provide access to icy water and other resources trapped underground." – Franceso Sauro, director of ESA's Pangaea planetary geology astronaut training

Key Details

The mission concept developed by the European research consortium unfolds in four distinct phases. In the first phase, robots work together to map the area around the lava tube entrance. The second phase involves dropping a sensor package into the cave to gather initial measurements of the underground environment. In the third phase, a scout rover is lowered into the cave through the entrance. The fourth and final phase sees the robotic team exploring deep into the tunnel and creating detailed three-dimensional maps of its interior.

The system relies on autonomous operation, meaning the robots can make decisions and navigate without constant instructions from controllers on Earth. This capability is essential for lunar exploration, where communication delays make real-time remote control impractical. The consortium included contributions from the University of Malaga and the Spanish company GMV, alongside the German Research Center for Artificial Intelligence.

The Lanzarote Test

The field trial conducted in Lanzarote in February 2023 demonstrated that the approach works as planned. The volcanic caves in this Spanish location provide an environment similar enough to lunar conditions to test the robots' capabilities. The trial confirmed the technical feasibility of the mission concept and showed the potential of collaborative robotic systems for future planetary exploration.

Researchers are also developing specialized equipment for cave exploration. Scientists have created a soft, deployable wheel designed specifically for navigating the challenging terrain inside lava tubes. This wheel can be compressed to a diameter of 230 millimeters for storage on a spacecraft, then expanded to 500 millimeters for use. Testing has shown it can handle obstacles, perform stable movement on rocky surfaces, and survive impacts equivalent to a 100-meter fall under lunar gravity conditions.

What This Means

The successful testing of these robotic systems represents progress toward a major goal in space exploration: establishing permanent human presence on the Moon. Lava tubes offer advantages that surface bases cannot match. They provide protection from extreme temperature swings, radiation exposure, and the constant bombardment of micrometeorites that characterize the lunar surface. This makes them far more suitable for long-term habitation.

The European Space Agency is not alone in this effort. Multiple space agencies and research institutions are developing technologies for lunar exploration and eventual human settlement. The work being done in Europe complements similar efforts elsewhere, advancing the broader goal of making the Moon a destination for sustained human exploration.

The robots being developed today will likely serve as scouts and support systems for the astronauts who venture into these caves in coming decades. By mapping the caves and gathering data about their conditions, robotic missions will help planners decide where to locate future bases and what resources are available. The technology is still being refined, but researchers say the path forward is clear. Future missions to the Moon and Mars will increasingly rely on teams of autonomous robots working together to prepare the way for human explorers.