The animation makes me melancholy. It’s a crudely rendered group of white, heavily pixilated concentric circles representing planets in orbit around the sun. Produced in 1977 to illustrate the trajectories of the “twin” spacecraft, Voyagers 1 and 2, the animation has a video game quality that begins with a god’s-eye view looking down on the solar system. The angle changes, zooming closer in to the orbital plane to focus on the dots that represent the three inner planets and the sun. Two white lines zoom away from the Earth dot and together they head toward Jupiter. Voyager 1 gets there first at the beginning of 1979, even though it was the second of the craft to launch, flung into space on September 5, 1977, just 16 days after its sibling, which arrived at Jupiter a few months later.

Both trajectories turn sharply left, heading for the next stop on their “Grand Tour” of the outer solar system. At the white dot that represents Saturn the spacecraft part company, Voyager 1 heads up and out of the ecliptic plane while Voyager 2 takes another hard left and continues toward Uranus. The line representing Voyager 1 disappears completely, leaving Voyager 2 to finish the journey alone. The animation slows down in an attempt to represent the great distance between the orbits of Saturn and Uranus. This change in speed feels like a shock absorbed, the way time slows down after a trauma, expressing both loss and determination — the inability to go on melodramatically coupled with the inability to quit. And yet the line keeps moving, again veering left around the backside of Uranus, slowing even more as the spacecraft makes its way to Neptune. When it reaches that planet, the animation zooms out again to depict the journey arrested at that point. The Voyagers began their adventure together, but became separated mid-stream, each continuing on solo through the vastness of space.

This wistful animation represents an adventure that continues today, 40 years later, while illustrating the separation of twins. The parting feels abrupt; the action seems rash and ill-advised. Wouldn’t the two craft be safer in the unknown together?

Of course, they were never together, these pixilated white lines only make it seem that way. They were always separated by weeks, months and now years. They encountered the same things, visited some of the same spaces, but hung out in different neighborhoods. They were fraternal twins, programmed to see differently from the beginning. Each was sending postcards of the trip back home, but they weren’t sharing their experiences with one another. They didn’t have a disagreement over where to go next. There was no heated argument, no falling out on the platform of a train station, one continuing on as planned, the other taking the next train to elsewhere. It only feels that way when we see their paths diverge.

On its way out of the heliosphere, Voyager 1 was instructed to turn back and take a picture, or series of pictures of the planets it could locate as it zoomed away. This composite is called the “Family Portrait” and features an image of Earth as a “pale blue dot” bathing in what looks like a band of sunlight. (Is it a lens flare effect of some kind?) All the language surrounding the Voyagers was designed to create an emotional bond between us and them. They were “twins” on a “grand tour,” the kind of trip that marked a privileged coming of age — a test of self reliance. These twins were sent to the far reaches of the solar system to gain valuable knowledge and experience, to see the sights and send back impressions of the ancient monuments found there. They are equipped with record players and 8-track tape decks, like teens in hatchbacks cruising main. One took a snapshot that encouraged us to see ourselves as a sibling in a family of heavenly bodies, while also demonstrating our incredible smallness even within our own tiny neighborhood.

Each Voyager points insistently back at Earth while speeding away at roughly 38,000 miles per hour, a speed that will never decrease as long as space remains frictionless. Both still share their discoveries in unexplored regions, measuring energy waves and particle densities that arrive as haunting audio chirps transmitted back to eager ears.

In 2012, Voyager 1 exited the heliosphere and entered interstellar space on its way toward Gliese 445, a nearby star. It will fly relatively close to that star in about 40,000 years, provided it does not collide with any other objects as it makes its way through the Oort Cloud, a region of comets and other bodies believed to have also been ejected from the solar system. Voyager 2 is heading toward Sirius, the brightest of the stars in our nighttime sky and, barring interruption, will arrive there in roughly 296,000 years.

It’s estimated the spacecraft have enough energy to continue to communicate with Earth until 2025, at which time they will both go silent, which is another concept that fills me with sorrow. Their energy output is currently so low it is as if they are travelers in a barren landscape mumbling to themselves about the cold. I cannot help but anthropomorphize. A part of me drifts in space inside of them, next to, perhaps the romantic Golden Record that lovers Carl Sagan and Ann Druyan produced together that can, if understood and enabled, play back the sounds of 1977 Earth. I have heard snippets of the actual contents of this record — “hello” in many languages, the sound of a mother and child, wildlife and nature, folk songs and industry — but imagine instead a mixtape of pop hits from that year in its place. “Strawberry Letter 23” followed by “You Don’t Have To Be a Star” and “Dreams”. The Golden Record contains the potential song the machines can sing to whoever or whatever might find them. It insists, like Dr. Seuss’ Who did for Horton, “We are Here!” Well, we were here. By the time anyone hears our song we will be long gone. The Voyager twins may be the only evidence that we ever were.

I can feel them as they speed away, but still call back. “Protons from the sun decreasing, I can no longer feel the rush of the solar wind or the tug of the sun’s gravity. Plasma flows increasing, a river coming from somewhere else, flowing around the heliosphere. I am swimming now in a stream of energy that crackles throughout the giant galaxy of which I am but a blip from a blip that circles another insignificant blip.” The further the spacecraft get, the more space yawns between them. They travel away from each other and away from us. They are a part of us that wants to know, that wants to say hello, but the reality they face is the immenseness of distance and its relationship to time.

The word “voyager” is somehow syllabically sad, calling to mind the melancholy of Now, Voyager, a 1942 movie for a Sunday afternoon. “Don’t let’s ask for the moon; we have the stars.” The spacecraft that bear this name demonstrate the pathos of our isolation. We are stranded in a little corner of space, unable to bend the laws of physics to access other regions of even our own galaxy, much less traverse the great expanses between galaxies in the infinity of the universe. The Voyagers generate a boundless optical zoom similar to the one in the first half of Charles and Ray Eames’ Powers of Ten, but continuing outward forever. The rubber band that would draw them back grows cold and dry and cracks, releasing them from the grip in which we ourselves are trapped.

Voyager 2 will soon enough join Voyager 1 escaping the effects of the sun. While I contemplate this motion, I am perpetually unable to quite grasp my own smallness. I imagine the Voyagers in the interstellar medium and my imagination balloons out to meet them. I become one of them, having separated in a huff from my twin and set my own course, not realizing that the instant I made that decision my fate was sealed. I will wander alone forever on an unknown and ultimately unknowable journey. My power supply will run out and I won’t be able to sense the particles around me or swerve to avoid any obstacles that might appear. I may never meet an end, instead continuing to drift forever, which is a barely comprehensible concept. I may never halt or be halted. In 2025, my resources depleted, I will die a lonely death, no longer able to communicate with home. I am momentum. I am a love letter in search of a lover.