Picture this: you walk out into the field on your property and you see a shiny silver ball on the ground in the grass. With red ribbons surrounding it and a crumpled parachute next to it. That’s what one Reddit user witnessed when they found a strange, perfectly round metallic ball in their pasture. The big question was: what is that?
It wasn’t a prop from a sci-fi movie or a leftover alien spacecraft. It was something much more terrestrial – and still cool – a radar calibration sphere!
Radar calibration spheres are, well, just what they sound like – a calibration tool for radar systems. They are ultra-reflective, spherical, and made of either metal or metal-coated objects. The purpose of a radar calibration sphere is to provide a consistent predictable target for radar systems. Hence the need to calibrate it out in the field.
The spherical shape is very important. With an irregular or angled object, there could be different signatures radar would read depending on how the object is oriented. A sphere has a constant radar signature no matter how its oriented. That is extremely important when you want to tune a sensitive detection system. Whether that is monitoring weather, getting the location of an airplane, or collecting data for a satellite.