From Radar Waves to Rhythm
Every six days a European radar satellite called Sentinel‑1 sweeps over the Dutch capital. While most people never notice the invisible scan, artist Bob de Jong decided to make the passage audible. By installing aluminium reflectors on the roofs of two iconic buildings – the historic Felix Meritis and the modern A’DAM Tower – he redirected a fraction of the radar signal back toward the satellite, creating a bright echo that could be measured and, ultimately, transformed into a beat.
How the reflectors work
The satellite does not take photographs; it emits microwave pulses and records the returning echo. Normally scientists use these data to monitor soil subsidence, ice‑sheet movement or flood risk. De Jong asked the system to “listen” to the city instead. The aluminium panels act like mirrors for the radar waves, sending a stronger signal straight back to Sentinel‑1. After installation the echo from Felix Meritis jumped from about –5 dB to +3 dB – a four‑ to eight‑fold increase in intensity.
Timing, angles and patience
Because Sentinel‑1 flies in a slanted orbit, the reflectors had to be angled with centimetre precision. The Dutch firm Terramira calculated the exact tilt so that the reflected beam would meet the satellite travelling at roughly seven kilometres per second. Any adjustment required waiting six days for the next pass – the satellite’s schedule cannot be altered on demand.
Turning data into sound
Decibels are the common unit for both radar strength and audio volume. De Jong used the periodic six‑day passes as a natural metronome, while the varying echo strength supplied the pulse. He then mapped these values onto pitch, tempo and timbre, creating an artistic interpretation rather than a literal translation. The result is a composition that feels like an electric guitar amplified by a space‑age amplifier.
Public engagement
The project, supported by the Netherlands Space Agency, culminated in a short film released on 21 October. During the Amsterdam Dance Event (ADE) the A’DAM Tower reflector was displayed on the Lookout platform, inviting visitors to experience the invisible satellite traffic as a tangible rhythm.
Bob de Jong’s experiment shows that everyday infrastructure can become a participatory instrument, letting citizens “see” and “hear” the sky’s surveillance in a creative new way.