You’re all familiar with optical telescopes, and may have even used one to look at the moon or one of our neighboring planets. But, the truth is that most of stunning astronomy photos you’ve seen of nebulas and galaxies were created with the help of radio telescopes. They may be composited with optical photos, but processed radio telescope “images” are how we can see gases and elements in space. To see the full spectrum you need a large radio telescope, but that didn’t stop 16-year-old Gonçalo Nespral from building a small, semi-portable version.
Nespral’s project uses a small satellite dish, which can only pick up short wavelengths in the radio frequency spectrum between 10.7Ghz and 12.75Ghz. It can be used to take pictures of the sky, but those frequencies don’t include much in the natural spectrum. However, they do include television satellite signals — that is what the dish was designed for, after all. So, Nespral can use this little radio telescope to build an image of the TV satellites in geostationary orbit.
For that to work, the radio telescope needs a way to accurately scan the sky. Nespral accomplished that with a custom mount made from from 3D-printed parts. The mount is motorized and controlled with a Raspberry Pi, and can tilt the dish up and down as well as rotate it. Once the dish is in position, the Raspberry Pi is used to measure the intensity of the radio signal being received. It can then repeat that process, moving from point to point, until it gathers enough information to composite a complete “picture” of the radio signals coming from space.