The Voyagers have reached an anniversary worth celebrating

Humans have launched some momentous missions of discovery into the universe. Yuri Gagarin reached orbit. The Apollo astronauts walked across the Moon. The Viking probes landed on Mars. But never before had a spacecraft visited four worlds in a single, grand tour as the two Voyager probes did in the 1970s and 1980s with Jupiter, Saturn, Uranus, and Neptune. And the story behind these two spacecraft, along with the people who made them fly, is utterly compelling.

Fortunately, on their 40th anniversary, PBS has produced a 90-minute documentary worthy of these missions. Featuring interviews with many of the principal scientists and imaging experts, The Farthest tells the story of how Voyager 1 and 2 were conceived, where they flew, and what they discovered while detailing all the drama in between. The documentary debuts on August 23.

Before the Voyagers launched, humans had been looking at fuzzy blobs in the outer Solar System for hundreds of years. Pioneer 10 and 11 provided some better views of Jupiter and Saturn, but still very little was known about the planets or their moons. Next to nothing was known of Uranus and Neptune. The Voyagers uncovered complex planetary systems and incredible moons, such as volcano-covered Io, icy Europa, and Titan with its methane seas.

There are lots of tidbits here that most of us have either forgotten or never knew. Initially, President Richard Nixon only authorized the spacecraft to visit two worlds—but secretly the scientists kept open the possibility to visit all four. Voyager 2, the first of the two spacecraft to launch, was nearly lost during the turbulent liftoff, when the rocket's vibrations convinced the spacecraft's sensors it was breaking apart. And after mission managers decided to include a phonograph of human sounds, including music, Carl Sagan only had a few weeks to make the selections. This frenetic rush on Earth set up years of discovery in deep space.

The archival footage is spectacular, too. After the Voyagers moved beyond Neptune toward interstellar space, the scientists held a big party at the Jet Propulsion Laboratory in California. Chuck Berry played, since his rock-n-roll graced the golden record aboard Voyager. Carl Sagan danced. What a time to be alive.

The Voyager program was the Apollo program of robotic spaceflight—one of America's iconic spaceflight missions of exploration. It's a good thing that PBS produced this documentary on the 40th anniversary rather than the 50th anniversary of the spacecraft launches. As we have seen with the Apollo program, many of the luminaries involved in the lunar expeditions, most notably Neil Armstrong, have died before reaching the golden anniversary. Here, most of the principal scientists involved in Voyager—except for Carl Sagan, who died in 1996 at the age of 62—are alive and well. And golly, do they have wonderful stories to tell.

Listing image by Tangled Bank Studios