On August 25th, 2012, humanity became an interstellar species. There was no fanfare or galactic welcome party as a humble robotic probe, the Voyager 1 spacecraft, crossed an invisible threshold. It slipped between the region dominated by the physics of the Sun and into the thin milieu of plasma between the stars.

Whatever fate befalls us now, whatever future civilizations rise and fall, whether we heal the Earth or continue our self-destructive path, we will still, and always, have this. A monument, a marker, a testament to the existence of our species and the ingenuity of our minds. It’s unlikely that any alien civilization will encounter our spacecraft, yet it will still exist, circling the center of the Milky Way for eons to come.

In the coming decades, Voyager 1 will be joined by other craft sent along solar-escape trajectories: the Pioneer probes, New Horizons, and more. And now that we’ve crossed this astrophysical threshold, we are forced to ask a difficult question: Is this it? Is this all we’ll ever accomplish beyond the Solar System, a scattering of wayward probes sent out into the infinite night?