The 40th anniversary of NASA’s launch of the Voyager mission is highlighted in a program that will air tonight on Public Television.

The documentary, titled “The Farthest,” includes comments from University of Iowa professor and astrophysicist Don Gurnett.

“I’m the principle investigator in charge of one of the instruments on Voyager. I have been involved in that, well, for 40 years. More than that, I started in 1972,” Gurnett said. In the film, the 77-year-old Gurnett talks about just a few of the historic discoveries of the twin spacecraft.

Don Gurnett

“I talk about the discovery of lightning at Jupiter,” Gurnett said. “It’s the first planet where we ever discovered lightning, other than Earth.” Gurnett gained worldwide acclaim 4 years ago when he officially determined that Voyager 1 had entered interstellar space.

The spacecraft has flown further than anything else produced by humans – and it’s still going. According to Gurnett, Voyager continues to collect information – on top of the historic images and data gathered many years ago.

“It took the first close-up pictures of Jupiter, Saturn, Uranus and Neptune. I mean, what a mission,” Gurnett said. “Not only the planets, but all their moons. And it’s not just the pictures, but staggering discoveries.”

Gurnett has been teaching at the University of Iowa for 52 years. He got his start building spacecraft instruments as an undergraduate at the UI in 1958, under space pioneer James Van Allen. The Farthest premieres on PBS tonight at 8 p.m. (CST).