"What I've found is if you look backward too often, that becomes your excuse, your evidence that you care," said astrophysicist Neil deGrasse Tyson, when asked about the importance of this month's 40th anniversary of the Voyager missions during a conversation at his office the Hayden Planetarium at American Museum of Natural History.

"But then, nothing happens going forward."

Despite Tyson's warning about spending too much time in the past, the magnitude of Voyager as a scientific achievement is the kind of thing that nevertheless demands recognition. That's on the way, in the form of the new documentary The Fartheston PBS.

Forward-looking admonitions aside, Tyson was on hand to play host to the film's premiere at the museum earlier this month. Using still imagery and archival video, the film’s narrative gets a great, crucial enhancement in the presence of the original mission’s crew, whose passion for the mission is still apparent, even decades later.

Voyager 2 was launched by NASA on August 20, 1977, followed a couple of weeks later by the launch of Voyager 1 on Sept. 5. Both probes were tasked with exploring the outer reaches of our solar system. The Farthestdetails what it took to launch those missions, and how the probes delivered stunning images and information about planets we'd previously only seen from afar.

Unlike many science docs, which often struggle to blow off the sleepy dust of history, The Farthestmanages to get across the enormity of the mission and its impact, all without the oft-used crutch of science fiction to capture our imaginations.

"We knew nothing about the outer solar system [prior to Voyager]. It was true exploration," says Carolyn Porco, a planetary scientist who was part of the Voyager imaging team. "You could do it again, but it’s not going to have the same effect."

Aside from the valuable data the Voyager flybys delivered on Jupiter, Saturn, Uranus, and Neptune (and their surrounding bodies such as Europa, Io, and Triton), the probes each carried a golden record containing music, images, and audio messages designed to expose Earth's civilization, culture, and environment to a possible alien civilization that might one day find one of the records.

The audio recordings were engineered by none other than Beats co-founder and Apple executive Jimmy Iovine, as Pharrell (who got the story from Iovine firsthand) explained to Tyson during a discussion on Beats 1 radio just last year.

The metal records contain 100 images, the natural sounds of Earth (such as the call of a humpback whale, for example), and spoken messages in 55 languages. (You can listen to the sounds on the golden record on NASA's SoundCloud page).

Included with the golden records are a stylus for playing the records, as well as instructions drawn on the record showing anyone (presumably, an alien race) how to use it. Also engraved on the cover of the housings carrying the records is the location of Earth’s solar system in relation to various pulsars

"The possibility that any civilization is going to pick up this tiny machine going through the emptiness of space is almost next to nothing," says Porco. "It was really a gesture that was meant to resonate with people back home, and give them a sense of belonging to the cosmos."

And while the new film offers our best look yet at Voyager and what it means to space exploration of the past, Porco is even more excited about a more recent mission: Cassini. Porco led the successful 13-year mission's imaging team. In 2015, the Cassini probe detected hydrogen during a flyby of one Saturn’s moons.

"One of the scientific questions we're left with as we see the end of the Cassini mission is whether there's life on the small moon Enceladus," says Porco, who mentions that there are private interests in Silicon Valley looking to fund a mission back to Enceladus to search for life.

"It's the only place in solar system besides the Earth that checks ‘all’ the boxes. Mars doesn’t check all the boxes. Europa doesn’t check all the boxes."

So as The Farthest looks 40 years into NASA's epic past, as Tyson wisely suggests, its team continues to look into the future with new missions to understand the universe, and our place in it.

"You can convince yourself, by celebrating anniversaries that you care about the subject," says Tyson. "If you reallycare about the subject, you might also do that, but you'll also be planning future missions."

The Farthestcan be viewed via streaming on PBS.org and will be broadcast again on PBS TV stations on September 13.