As Voyager 1 cradles the edge of our Solar System, poised to enter the vacuous expanse of deep space, we are approaching a milestone that many on this planet are not aware of. As this magnificent example of human engineering leaves the confines of the warm embrace of our Sun, at ~120 AU a now faint and distant beacon in the enveloping darkness, we will become an interstellar species. The gravitas of this monumental achievement should not be overlooked.
Whilst it remains theoretically feasible that our universe may be teeming with life, intelligence of space-faring calibre may be exceedingly rare. We, the product of a knife-edge balancing-act between biological, geochemical and astronomical implausibility, are lucky to be here at all. The inordinate complexity, the innumerable coincidences and the eventual culmination of 3 billion years of evolution – we stand on the peak of the impossible, gazing out into the void, with Voyager as our first envoy to the stars.
It is unlikely, but not impossible, that any interstellar civilisation has come before us. We’ve been listening for our galactic neighbours, via the enormous ear of SETI, for over 50 years to no avail. No radio chatter, no xenoarchaeology nor ambassadorial spacecraft. Given the ubiquity of planet forming material, and what we consider the relative normality of our watery home, the emptiness – the silence, is paradoxical.
The galaxy is ~13.2 billion years old and our 4.5 billion year-old Solar System has orbited its centre ~25 times. This planet has been habitable for around 4 billion years, and based on our best estimates, we have another half a billion or so to go before the evolution of the Sun renders the planet uninhabitable. We’ve been hitching a ride through space for one hundredth of one percent (5 million years) of the age of our planet, and have had space technology for one thousandth of that time (50 years). Assuming this is the case for most habitable planets, and knowing as we do that exponential colonial growth is impossible, it seems likely that if intelligent civilisations had arisen at any point in the history of our galaxy, and at some coordinate closer to the galactic core, there has been little evidence to suggest that they ever made it out this far. Given that colonisation infers a survival value, the fact that nearby planets give no indication of being inhabited leads to the conclusion that there are likely to be no other colonisers out there.
What conclusions can we draw from the silence? Well, conjecture abounds. Perhaps the galaxy is teaming with civilisations who have consciously hidden themselves from us until we overcome some technological or societal hurdle that would usher our entry into the ‘galactic club’ – perhaps superluminal travel or the formation of a world government? Who knows. In the immediate future, and without too much speculation, we can possibly infer that we may be the only intelligent civilisation ever to have arisen, in this neighbourhood anyway. If so, that places quite a burden on us, whether we realise it or not, to protect our planet and each other until such time that we can make our own way through the stars. We, or most likely our distant descendants, may be the sole custodians of the true meaning of existence, nature and the universe; the formulators and keepers of the ‘theory of everything’. Their success, and ours in the meantime, depends on the decisions we make now.
We are the pioneers, but we are also most certainly endangered by our own machinations. Up to this point, some of those decisions have been rather poor and have possibly compromised the very habitability of the planet we draw life from. Others, like Voyager et al. have been great. This humble, unassuming vessel represents the first step of an infant civilisation adopting a truly universalist, extrospective outlook. With 10 – 15 years of power left, Voyager will continue to take measurements and beam information back to Earth on the transition through the heliopause and the composition of the interstellar medium. After its batteries have died and its instruments have gone silent Voyager will continue to obediently sail through the depths of space on a mission lasting an eternity; a mission with no end and no more formal objectives. The spacecraft will not decay in the vacuum of space and its form and technology will be preserved indefinitely as a timecapsule to the stars. Long after the Earth has ceased to exist, Voyager will remain.
What a truly magnificent thought! It is humbling to be part of the first generation of interstellar human beings and an honour to have Voyager as our flagship.