How the Navy used the Moon as a giant radio mirror

Space · Published 18 October 2026 Swipe more like this →

In short: Before the era of satellites, the Moon served a vital strategic purpose. By bouncing microwave signals off its lunar surface, the U.S. Navy established a secure, global communication network that bypassed the unreliable ionosphere, turning our natural satellite into a passive relay station for clandestine operations.

The concept of Earth-Moon-Earth (EME) communication, or 'moon bounce,' relies on using the lunar surface as a passive reflector. While the idea was proposed as early as 1940 by W.J. Bray, the first human voice transmission was successfully bounced back to Earth on July 24, 1954, by the Naval Research Laboratory in Maryland. This breakthrough offered a solution to the volatility of high-frequency radio, which was often vulnerable to foreign detection and atmospheric interference.

By the early 1960s, this technology became central to the Navy's Technical Research Ship Special Communications System (TRSSCOMM). To carry out such missions, the Navy repurposed WWII-era Victory and Liberty class cargo vessels, renaming them Auxiliary General Technical Research (AGTR) ships. These vessels, such as the USS Oxford, carried specialized equipment to beam signals toward the Moon, which would then reflect back to ground stations strategically placed in 90-degree quadrants around the globe, including locations in Maryland, Hawaii, England, and Japan.

The system's utility was proven on December 15, 1961, when a message was sent from Stump Neck to the USS Oxford, located approximately 2,414 kilometers in the Atlantic Ocean. While the advent of communication satellites in the 1960s eventually rendered TRSSCOMM obsolete for military use, the technique lives on through amateur radio enthusiasts. These hobbyists continue to use EME to achieve the longest possible communication paths between two stations on Earth, often using surprisingly low-power signals.

The history of the technique also includes unexpected moments of scientific discovery, such as 1943 German radar experiments that inadvertently detected the rising moon, and the 1970 feat by Australian amateur Ray Naughton, who achieved moon bounce using a home-built antenna and only 100 watts.

General information, not professional advice. Spotted an error? Flag the card or see corrections and complaints.

Intellect Plus is a visual educational discovery platform for exploring fascinating facts and ideas. Brain Food, Not Brain Rot. What is Intellect Plus?

Related

• Engineers once scattered 350 million copper needles in orbit to bounce radio signals
• How a Soviet probe proved the Moon was solid enough for human footsteps
• In 1959, a Soviet probe became the first human-made object to touch the Moon.
• From Cold War competition to a permanent lunar base: the evolution of moon exploration
• To reach the Moon, NASA turned back the clock on color TV
• You can't own the Moon, but you can still buy it
• Why your mental image of the Moon is likely incorrect
• The Moon's gravity is far from uniform or simple
• Lunar craters create fluffy regions that stay freezing during the night
• To reach deep space, we must learn to live off the land
• The Moon once possessed a thick atmosphere capable of driving windstorms
• A lunar outpost as a mirror for an energy-starved Earth

More in Moon · More in Space · Latest · A–Z · All topics