Third International Planetary Caves Conference

Caves on Earth are formed due to a variety of processes ranging from volcanism to fluid erosion. Most of these processes operate on terrestrial planets and moons within our solar system. More than a thousand possible cave entrances have been identified on Mars and hundreds on the Moon thanks to the use of high-spatial resolution-instruments such as the High Resolution Imaging Science Experiment (HiRISE) and Lunar Reconnaissance Orbiter Camera (LROC). Some rocky and icy planetary bodies in the solar system are expected to have caves as well — including possible cryovolcanic vents on Pluto and icy fissures on Enceladus, Titan, and Europa.

The 3rd International Planetary Caves Conference focused on the science and exploration of planetary caves and brought together 55 terrestrial and planetary scientists and engineers (including 16 students) to discuss scientific advances and engineering capabilities for planetary cave exploration and research. Participants considered cave formation mechanisms, preserved geological records, cave microclimates, astrobiological potentials, engineering challenges of subsurface exploration, and potential robotic missions to explore the subsurface of other worlds.

As part of the conference, participants visited two caves:  a commercial cave and an undeveloped, natural cave. These two caves highlight both the spectacular geological beauty of caves and the challenges of robotic exploration. The natural cave was a practical labyrinth — where real-time, in situ mapping, combined with autonomous navigation, would be a necessity for any robotic mission.

Participants agreed that Mars’ caves are excellent sites to search for the signs of either extant or extinct life. Attendees highlighted how methods such as pattern recognition algorithms and ultraviolet fluorescence imaging technology may facilitate the search for life elsewhere. One presentation discussed the continuum of biotic/abiotic deposits, suggesting the cave deposits are not necessarily a binary option.

Attendees considered the overlap of the locations of possible in situ near-surface resources with known locations of potential cave entrances. For example, the presence of near-surface ice preserved in caves may provide a resource for both indigenous life (primarily Mars) and the sustainment of future human missions (Mars and the Moon).

Multiple robotic architectures to enable planetary cave missions, ranging from lowering instrument packages into a cave via tether (much like rappelling into a cave) to crawlers that can climb and/or descend on the surface of near vertical slopes (much like rock climbers do), were discussed. Robotic capabilities are being enhanced by advances in artificial intelligence, which will aid in subterranean navigation, sample selection, and sample analysis. Participants agreed that a practical approach to planetary cave exploration would include continued development of new technologies on Earth, demonstration of these technologies by exploring lunar caves, and ultimately deploying those technologies to Mars.

Finally, presentations highlighted how terrestrial cave environments can provide training opportunities for astronaut teams. Caves restrict mobility and communication, like the actual conditions on a space station. Teamwork and coordination are vitally important for accomplishing tasks in an unfamiliar environment. This approach adds another dimension to how cave exploration enhances overall exploration of the solar system.

For more information about the meeting, including links to the program and abstracts, visit

— Text provided by C. M. Phillips-Lander (Southwest Research Institute), T. N. Titus (U.S. Geological Survey), P. J. Boston (NASA Ames Research Center), J. J. Wynne (Northern Arizona University), and L. Kerber (NASA Jet Propulsion Laboratory)