It’s taken 1000 people and 20 years, but the James Webb Space Telescope (JWST) is nearing completion. Once it’s done, NASA will attach the $8 billion project to a rocket and shoot it into space, where the telescope will begin its search for Earth-like exoplanets. This weekend, the Discovery Channel will premiere TELESCOPE, a behind-the-scenes documentary on the project.

Matt Mountain is president of the Association of Universities for Research in Astronomy (AURA) and former director of the Space Telescope Science Institute. As a manager, he’s acutely aware of the risks. There is a chance, after all, that the telescope could fail to deploy, or that it will be damaged in the launch. Mountain tells mental_floss that if the JWST fails, “it will be a disaster.”

But he remains optimistic. “In all science, there’s always risk,” Mountain says. “We’re doing something nobody has ever done before. We’re building the largest space telescope anybody’s ever built. We’re going to send it out a million miles and we’re going to deploy it. We just hope that we’ve done enough testing and checking here back on Earth that that won’t happen.”

The JWST has a number of scientific objectives. Astronomers know that the universe began with the so-called Big Bang, and that an explosion eventually became millions of galaxies. What happened in between—what astronomers call the Dark Ages—remains unseen. The JWST will use its powerful imaging capabilities to search for evidence of this missing period of cosmic history.

Just as amazing, Mountain says, is the JWST’s potential to discover Earth-like exoplanets—planets that are not too big or too small, too hot or too cold: “Now, we’ve got to be very lucky, because we don’t know where all these planets are yet, but if it’s about the size of the Earth, and it’s in the goldilocks zone, it can hold liquid water. And liquid water is the prerequisite for life. And then we’ll know where to look for life in another planetary zone. That would be damn cool.”

Speaking in the documentary, astronomer and planetary scientist Sara Seagar agreed: “Another Earth is undoubtedly out there.”

As a telescope expert and enthusiast, Mountain is also excited about the documentary. “The telescope has been one of the most transformative instruments in human history,” he says. “Before telescopes, the Earth was thought to be the center of our universe. Then we discovered that, no, it was the Sun, because of Galileo. And then with telescopes we discovered that those funny things we saw in the sky were not just nebulae—they were other galaxies. Every time people had theories, whether it be from Plato and Aristotle, Ptolemy, or even Einstein, telescopes have revealed a universe that people hadn’t expected.”

Like the Hubble, observations made by the James Webb Space Telescope will be accessible to everyone via images uploaded to the Internet. “That’s why telescopes have been so powerful,” Mountain says. “Everybody can come on this journey.”

The James Webb Space Telescope is scheduled to launch in 2018. TELESCOPE will air Saturday at 9 p.m. EST on the Discovery Channel and Sunday at 9 p.m. EST on the Science Channel.