Caves are not the best place to fly a drone.
The walls are irregular, the signals that make remote control easy are difficult if not impossible to work underground, and the drone itself could get lost and stuck somewhere difficult to retrieve. However, with the right drone, and the right conditions, cave mapping becomes an ideal drone task.
Think of it: LIDAR sensors can map the interior of unexplored chambers and keep the drone away from collisions. Autonomy can work without a need for remote piloting. And, most of all, it’s far easier to first send a drone where people haven’t been then it is to send a person.
There are military implications for this — and we’ll get to them momentarily — but consider first the scientific use case. Drones that can map caves would prove valuable for underground mapping, in places inhospitable, inaccessible to humans, or just plain under-explored. Techniques built to fly drones in caves on Earth could inform drones deployed on future robotic expeditions to the Moon or Mars or elsewhere with visible entrances to lava tubes.
A research team from SETI Institute, Mars Institute at NASA’s Ames Research Center, space robot maker Astrobotic, and Geo Travel Iceland flew a hexacopter inside Iceland’s Lofthellir lava tube. The science itself is, again, fascinating, but it’s the application in other domains that is our particular interest. Focusing purely on the mapping, the flight at Lofthellir showed how a special navigation and mapping system, built for GPS-denied environments, was able to plot out the interior of the cavern.
These are many of the same characteristics sought after by agencies such as DARPA that are presently exploring how the military can operate in underground environments. Designing for GPS-denied spots is at least as useful on other worlds as it is in caves on this one. Autonomy is one of the better ways around this hurdle. Mapping the interior of spaces creates useful information for anyone hoping to maneuver inside or plan around the underground environment. Inasmuch as this cave mapping is built on commercial technology, it can be adapted to military missions.
The limitations are not insignificant. Getting the data from the drone to the computers that process it and render it useful for humans takes some work. Operating underground is a challenge by itself. Operating underground at military speeds and with hazards of battle likely require not just effective tools, but fast ones. The maps plotted, too, may not have all the information needed for people who are going to follow the drone down the unfamiliar tunnel, and an assumption of more knowledge than exists could prove risky.
Still, most of the expected underground environment of future conflicts is likely human-built, so designing drones to map, say, an unfamiliar subway line should be a hair easier than plotting out an unknown lava tube.
Watch a video of the mapping in Iceland below: