Imaging the Moon’s interior with fibre-optics
Future lunar missions may rely on a fibre-optic cables to assess vital sub-surface structures. Researchers at ETH Zurich are investigating whether lightweight optical fibres – like those used for internet communication on Earth – could be deployed on the Moon to detect seismic activity and reveal its interior structures.
In brief
- Scientists propose fibre-optic cables as dense, lightweight seismic sensors on the Moon.
- Laser-based Distributed Acoustic Sensing (DAS) technology could map lunar interiors using vibrations from Moonquakes, lunar landings, and meteorites etc.
- The Moon’s conditions make this method especially effective for future exploration.
It was 1972 when the last Apollo astronauts deployed seismic instruments on the Moon. The Apollo instruments operated until 1977 delivering a dataset consisting of thousands of moonquakes. Today’s scientists still rely on that data, but it offers only a glimpse into the Moon’s interior.
This is why researchers at ETH Zurich, led by Johan Robertsson, Professor of Applied Geophysics at ETH Zurich, and international partners including the Los Alamos National Laboratory in New Mexico, USA, are assessing a novel approach to studying the inner geological structure of the Moon. Instead of deploying heavy seismometers one by one, a rover could unroll kilometres of light-weight fibre-optic cable across the lunar surface. The cables would act like thousands of tiny sensors detecting tremors from moonquakes, meteorites, and lunar landings. This is demonstrated in their study just published in the journal external page Earth and Space Science.
Using light to detect moonquakes
Using a “Distributed Acoustic Sensing” (DAS) technology, researchers turned a fibre-optic cable into a long-range sensor. Lasers in DAS send rapid pulses of light through a cable and tiny imperfections in the fibre scatter light back to an instrument called an interrogator. By analysing the returning light, scientists can detect seismic waves by how the cable stretches or vibrates.
The timing of the reflected signals reveals where along the cable the motion occurred allowing a single fibre, approximately the width of a human hair, to function like thousands of evenly spaced sensors. Even a cable a few kilometres long can record signals at a higher spatial resolution than traditional seismic networks. On Earth, DAS already monitors earthquakes, landslides, and even whale movements using ocean telecom cables.
Researchers report other use cases beyond quake detection. “Vibrations generated by spacecraft landings and take-offs could serve as active seismic sources, allowing fibre-optic cables to image the Moon’s sub-surface structures in a similar way to medical ultrasound,” says Simone Probst, lead author, and doctoral researcher in Robertsson's group.
The cables could also detect how much lunar dust is stirred up by rocket exhaust during landings. This information could help mission planners better understand and mitigate dust-related risks for future missions.
Fibre-optics may work better on the Moon
The Moon may be ideal for fibre-optic sensing. Probst and Carly Donahue, a former Senior Scientist at ETH Zurich, conducted shaker tests at the Los Alamos Lab using crushed basalt – a similar material to the fine powdery lunar soil called “regolith.” The lab tests showed promising results with thicker cables recording seismic signals nearly as well when lying in direct, continuous contact with the surface as when buried in the basalt.
“Understanding how cables perform under varying conditions is essential,” says Probst, lead author of the study. “We are complementing our experiments with computer simulations to study how cables couple with the ground, and how this interaction is shaped by lunar gravity.”
Researchers found that while wind weakens signals of cables on Earth, the Moon’s lack of atmosphere could make it possible to roll out cables on the surface instead of burying them underground. Simulations also model how cables respond to seismic waves under lunar conditions.
Learning more about lava tubes or water resources
“Fibre-optic sensing could dramatically expand our understanding of the Moon – its interior, lava tubes, landing sites, and water resources,” says Johan Robertsson, senior author of the study. “Long cables could also pick up signals of tidal stresses caused by Earth’s gravity allowing scientists better understand how seismic waves travel through the Moon. It has even been proposed that DAS could detect gravitational waves exciting the normal modes of the Moon.”
For the ETH Zurich team, the research is part of a broader effort to develop next-generation sensing technologies. If successful, fibre-optic networks could stretch across the lunar surface – turning the Moon into one of the most densely instrumented seismic laboratories beyond Earth.
Reference
Probst S, Zandanel A, Robertsson JOA, Donahue CM. Controlled source DAS coupling tests: Implications for unburied deployment on the Moon and Earth. Earth and Space Science 2026, 13: e2025EA004817, DOI: external page 10.1029/2025EA004817