Just under the surface of the Moon, subterranean caverns stretch out thousands of feet (hundreds of meters) in diameterâsome as much as 1,000 times more vast than similar lava tubes carved out by volcanic activity here on Earth. Scientists have long schemed about refurbishing these lunar caves into sites for exploratory bases on the Moon, given the cavesâ natural protection from cosmic radiation beneath thick layers of regolith and cooled magma.

And now, after decades of more speculative and long-distance research, it looks like NASA is putting its money where its mouth is. The U.S. space agency announced that it will fund research by Austin-based Stone Aerospace, Inc. to develop a tethered lunar-spelunking droneâpowered via laser light that will be beamed through a system of fiber optic cables conjoining it to a lunar rover on the Moonâs surface.

This power-over-fiber (PoF) design, according to NASAâs announcement, will manage the neat trick of meeting three critical needs for this mission: It will act as a typical broadband fiber-optic cable, assuring high-speed data transmission around otherwise impenetrable rock; it will provide onboard electrical power; and it will provide laser-enhanced thrust for the droneâs ânon-polluting cold-gas propulsion system.â

âThe proposed study could enable the first off-world cave exploration,â Stone Aerospaceâs physics lead Gilly Elor noted in a statement. âAdditionally, our technology has broad dual-use potential for terrestrial applications, enabling long-range continuous optical power transmission to mobile platforms on land, in air, or underwater.â

Pitch black

Like Earthâs lava tubesâincluding those recently studied by NASA astrobiologists in Hawaiiâthe Moonâs version of these geological formations were created as ancient rivers of lava plowed through the lunar landscape, cooling faster near the surface and leaving behind long, hollow tunnels.

As part of the proposed Lunar Underground eXplorer (LUX) mission, Stone Aerospaceâs hovering robotic explorer will descend into the Mare Tranquillitatis lunar skylight, a yawning chasm about the size of two football fields roughly 250 miles (400 kilometers) away from where Apollo 11 landed. The Mare Tranquillitatis skylight is known to be about 436 feet (133 meters) deep and was only recently discovered to be the portal to a cave network, thanks to radar data collected by NASAâs Lunar Reconnaissance Orbiter in 2010 but only just analyzed by Italian geologists in 2024.

Elorâwho was once a visiting research scientist at Lawrence Berkeley National Laboratory and a veteran explorer of deep caves like Sistema Cheve in Oaxaca, Mexicoâemphasized that there would be âserious challengesâ navigating the depths of Mare Tranquillitatis.

â[It] will be energetically demanding (due to complete darkness),â Elor wrote. There will be no GPS navigation to assist with the âcompletely un-mappedâ 3D environment, she added. And, on top of that, âthe system must be non-polluting so as to not affect sensor measurements of the pristine environment,â she said.

The descent

NASA awarded Elorâs team $175,000 for preliminary research into this mission as part of the $3.2 million in total that it dispersed via its NASA Innovative Advanced Concepts (NIAC) Phase I awards this July.

âNASA has outlined an ambitious vision for the future of space exploration, weâre returning the Moon to stay, advancing to Mars, and pushing to deepen our understanding of space,â NASAâs director of its Advanced Research and Technology division, Greg Stover, said in a statement.

âAchieving that will require more than incremental technological advancement,â Stover said. âIt means we need great leaps. These awards are the kinds of innovation the world needs NASA to help foster.â

According to Elor, Stone Aerospaceâs PoF drone designs will prove capable as NASA missions advance onward to the Red Planet as well.

âWhile other lunar lava tube mission proposals exist, none have the unique combinations of enabling elements of our concept,â Elor said. âTaken together we posit that these will significantly enhance the range, duration, and quality of science and exploration for subsurface lunar (and eventually Martian) exploration.â