The most comprehensive search for signs of intelligent life elsewhere in the universe has come up short so far, despite generating more than 1 petabyte of data. But such efforts are just getting started.The big picture: The project — known as Breakthrough Listen — observed more than 1,300 relatively nearby stars over the course of 3 years, listening for any signs of radio waves that would signal the presence of technologically advanced aliens.This only amounts to a tiny sliver of what could be studied.If you compare the volume of space we're able to search for signs of advanced technology to the volume of Earth's oceans, then "so far since 1960, we've searched about one hot tub's worth of the ocean," says longtime SETI researcher Jill Tarter.Where it stands: The $100 million Breakthrough Listen project, founded by Russian billionaire Yuri Milner, launched in 2015.It is expected to survey 1 million stars, 100 nearby galaxies and the galactic plane for technosignatures that presumably only an advanced society could send into space.The entire project will last a decade.On June 18, Breakthrough Listen publicly released the data it has gathered so far in the largest dump of its kind.The catch: Scanning the skies for radio signals from out there isn't easy. In order to pick up on whatever relatively faint signals might be emitted, scientists need to use sensitive radio telescopes on Earth to hear them.That might get harder in the future, however, as more large constellations of satellites are launched, making it even more difficult to listen for any faint signals.Meanwhile, it's not a sure thing that we have the capability to hear the calls of an advanced alien civilization."So there's always that possibility that we're just, you know, not at the point where we can pick up the signals easily. There may be lots and lots of signals, but we can't pick them up," SETI Institute's Seth Shostak told Axios.The backdrop: It's also possible — in fact more likely — that scientists will find life in another way that has nothing to do with hunting for technosignatures.Last week, NASA's Curiosity rover sniffed out methane on Mars, which could be a tantalizing hint of microbial life currently on the red planet.Scientists also hope to one day search water-rich moons like Enceladus or Europa that might harbor microbial life today.NASA's next generation telescopes could give scientists a glimpse of distant planets that might have environments ripe for life.What's next: There is an increase in SETI efforts around the U.S. and internationally.Breakthrough Listen, for its part, has a deal to eventually use China's huge FAST radio telescope and others to aid in the search."I always think SETI is kind of a reflection on our own capabilities as a civilization, and the things we're able to look for are limited by the technology that we have," Breakthrough Listen scientist Danny Price told Axios.