ET may be phoning home, but he’s not calling anyone else — not that we’ve heard, anyway. So far, the most extensive search for extraterrestrial intelligence to date has turned up empty. But the project isn’t giving up. In fact, it’s expanding the search by adding new telescopes.

Breakthrough Listen has been operating for about four years. It uses giant radio telescopes in the U.S. and Australia. They monitor billions of frequencies for signals from other civilizations. The project has kept an “ear” on more than 1300 stars that are within about 160 light-years of Earth. It’s also looked toward the center of the Milky Way Galaxy, and at several other galaxies.

But a couple of months ago, project scientists reported they haven’t heard a peep. All the interesting signals have been made either by human technology, or they’re produced naturally, by stars and other objects.

Yet the search is just getting started. It recently added a large array of radio telescopes in South Africa. The array should be able to “hear” more-distant signals. That will allow the project to monitor a million individual stars.

In addition to radio telescopes, Breakthrough Listen has used an optical telescope to look for laser beams. Such beams might be used for interstellar communication, or to push sail-powered spacecraft. And the project has added an array of four telescopes in Arizona to that part of the search — extending its efforts to find ET.

Script by Damond Benningfield