Today is the 40th anniversary of the launch of Voyager 1. Four decades later, both spacecraft survive, still producing science, still working on their interstellar missions. Still, for most of us here on Earth, the most important accomplishments of the Voyager missions were completed thirty years ago, with the first reconnaissance of what was then thought of as the outer half of the solar system.
Following the final planetary flyby, imaging team member and Planetary Society founder Carl Sagan spearheaded an effort to get Voyager 1 to look back at its birthplace, imaging Earth in the context of the solar system, as just one of many planets. That effort resulted in the famous Pale Blue Dot photo, of Earth as a mote of light suspended in a sunbeam. Sagan later wrote a book titled Pale Blue Dot, featuring a moving essay on how small Earth is in the vastness of space. You can read that essay here, or listen to actor Robert Picardo read Sagan's words:
The Planetary Post - Carl Sagan's Pale Blue Dot A reading of Carl Sagan's Pale Blue Dot by Star Trek's Robert Picardo, who also serves as a member of The Planetary Society Board of Directors and is the host of our monthly email newsletter, The Planetary Post.
The photo didn't just happen on the spur of the moment. Sagan envisioned its possibility for years. In the July/August 1989 issue of The Planetary Report (PDF), he spoke of his hopes for Voyager 1's solar system family portrait:
In this issue of The Planetary Report we celebrate the epic journey of the Voyager 1 and Voyager 2 spacecraft and look forward with keen anticipation to the Voyager 2 encounter with the Neptune system on August 25, 1989....
The spacecraft have opened most of the solar system -- both in extent and in mass -- to the human species. They represent a triumph of American technology, admired even by those who have deep misgivings about other policies of our nation. They provide an example of what contemporary human technology, freed to pursue peaceful exploratory objectives, is capable. The data are made freely available, much of it in real time, to all the citizens of our planet. Those who built and operated Voyager -- especially the engineering staff at the Jet Propulsion Laboratory, who time and again devised brilliant solutions to unexpected problems uncovered when the spacecraft, in effect, radioed home for help -- deserve our respect and admiration. They are real American heroes....
Neptune is the final port of call on Voyager's Grand Tour. There are no more worlds on its itinerary. Before Voyager 2 passes the planetary frontier into interstellar space, it has the opportunity to take (as I very much hope it will) one last picture -- over its shoulder, of the inner solar system. The planets will appear as a sparse sprinkling of points of light. One of them, a tiny blue dot set against the spangle of the Milky Way, will be the Earth. From the distance of Neptune, it will seem no more than a faint star. I believe that this picture could have a profound influence on how we view ourselves, as powerful as the images taken by the Apollo astronauts of our lovely, finite and fragile planetary home.
Sagan's hopes came true, of course. Here he is speaking to the press on June 6, 1990, at a briefing announcing the release of the Pale Blue Dot photo.
Carl Sagan Unveils the Pale Blue Dot Carl Sagan, Planetary Society co-founder, unveils the Pale Blue Dot image at a press conference on the Voyager missions in 1990.
The end of the Voyager encounters happened at a time when Sagan's writings showed increasing concern for the direction of Western culture. His two immediate post-Voyager works were Pale Blue Dot, about the preciousness and fragility of life in the universe, and The Demon-Haunted World, about the temptations and hazards of pseudoscience to our modern technological society. His editorial in the November/December 1989 issue of The Planetary Report (PDF) hints at these themes, his optimism and wonder at Voyager's accomplishments tempered by worry for the state of humanity.
Voyager left a planet blighted and imperiled by nuclear weapons, climatic change, poverty and injustice. The species that launched her was a danger to itself. But Voyager has given us a stirring cosmic perspective. We have seen evidence of the destruction and reconstitution of worlds. We have witnessed the early building blocks of life assembling themselves. But we have found not a trace, not a hint, of life itself. Voyager reminds us of the rarity and preciousness of what our planet holds, of our responsibility to preserve life on Earth.
If we are capable of such grand, long-term, benign, visionary, high-technology endeavors as Voyager, can we not use our technological gifts and long-term vision to put this planet right?
Perhaps the Neptune flyby marks not just Voyager's rite of passage, but the beginning of our own: the binding up of the peoples and nations and generations to take care of one another, to cherish the Earth and bravely to venture forth -- in the footsteps of Voyager -- to the planets and the stars.
The fact that both Voyager spacecraft are still functioning and doing science, 40 years after their launches, is reason for optimism. We can build robust, adaptable machines capable of surviving unpredicted storms and responding to new discoveries. We can build them, launch them, and stably operate them for four decades, and more. Can we now turn those skills homeward, to building an adaptable and sustainable society? Who knew that rocket science would be the easy part?