Moonquakes and Fiber Optics: A Recent Way to Explore the Lunar Interior
Researchers at Los Alamos National Laboratory are pioneering a novel approach to studying the Moon’s interior: using fiber-optic cables. This innovative technique promises a simpler, more cost-effective way to gather seismic data compared to traditional seismometers, potentially revolutionizing future lunar missions like those planned under the Artemis program.
The Challenge of Studying Moonquakes
Understanding the Moon’s internal structure is crucial for planning sustained human presence and robotic exploration. However, deploying traditional seismic sensors is notoriously difficult and expensive. Carly Donahue, a scientist at Los Alamos National Laboratory, explained, “The moon has a lot of seismic activity, but deploying traditional seismic sensors like seismometers is extremely difficult and costly.” Fiber-optic cables offer a lightweight, robust, and inexpensive alternative.
How Fiber-Optic Cables Detect Seismic Activity
The concept relies on a technique called distributed acoustic sensing. Laser pulses sent through the fiber-optic cables can detect tiny vibrations along their entire length, effectively turning a single cable into thousands of seismic sensors. This dramatically increases coverage compared to the limited number of instruments deployed during the Apollo missions in the 1960s and 70s.
Unlike earthquakes, moonquakes are triggered by different forces – Earth’s gravitational pull, meteorite impacts, and extreme temperature swings. The lunar surface experiences drastic temperature changes, exceeding 200 degrees Fahrenheit during the day and dropping below minus-200 degrees at night, causing expansion and contraction that generates small, shallow quakes. These quakes also last longer than their terrestrial counterparts, as the Moon doesn’t dissipate energy efficiently.
Lab Tests Mimic Lunar Conditions
To test the feasibility of this approach, researchers conducted experiments in an indoor lab at Los Alamos. They laid fiber-optic cables on and beneath crushed basalt, simulating the lunar surface. Studies published in the journals Icarus and Earth and Space Science demonstrated that the burial depth of the cables doesn’t significantly affect signal clarity. This is since the Moon’s thin atmosphere creates less noise than Earth’s, allowing for better signal quality even with cables placed directly on the surface.
Analysis revealed that stiffer, thicker cables with continuous ground contact improved signal strength. However, researchers are mindful of the trade-offs, as increased thickness adds weight, a critical consideration for spaceflight.
Beyond Moonquakes: Detecting Other Hazards
The potential applications extend beyond detecting moonquakes. Fiber-optic cables could also reveal other hazards, such as the blowing of particles during rocket landing on the Moon. This information is vital for astronaut safety and infrastructure planning.
What’s Next for Lunar Seismic Sensing?
The research team is now focused on selecting the optimal type of cables for deployment on the lunar surface. This technology could provide critical seismic data for future Artemis missions, helping to unravel mysteries about the Moon’s core composition and potential fault lines.
Frequently Asked Questions
What are moonquakes?
Moonquakes are seismic events that occur on the Moon, caused by forces like Earth’s gravity, meteorite impacts, and temperature fluctuations.
Why are fiber-optic cables a good alternative to seismometers?
Fiber-optic cables are lightweight, robust, inexpensive, and can function as thousands of sensors along their length, offering broader coverage than traditional seismometers.
How does distributed acoustic sensing perform?
Laser pulses sent through the fiber-optic cables detect tiny vibrations, allowing the cables to act as seismic sensors.
Explore further: Learn more about the research at Los Alamos National Laboratory.
