Imagine launching a giant, shiny balloon into orbit — not to take photographs, not to carry astronauts, but to bounce radio messages back to Earth. That's close to the thinking behind NASA's Echo programme.
Echo 1, successfully launched in August 1960, was a roughly 30-metre-wide sphere made from reflective Mylar. Unlike today's active communications satellites, it didn't have to amplify incoming signals. Instead, powerful ground transmitters directed radio waves at its surface and receivers listened for the reflections.
An orbital mirror.
This made Echo a passive communications satellite: the clever electronics could stay on Earth, while the object in space behaved like a vast reflector.
Echo helped demonstrate long-distance radio communications via orbit and became a visible symbol of the early space age. People on the ground could sometimes see the balloon moving across the night sky.
Today's satellites use far more sophisticated electronics. But the idea behind Echo remains beautifully direct: what if we put a giant mirror in the right place and let physics do the rest?
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This original short explainer was researched using NASA ↗. We link to source material so you can check the details and explore further.